Bellingham, Washington USA
Library of Congress Cataloging-in-Publication Data Palmer, James M. Art of radiometry / James M. Palmer and Barbara G. Grant. p. cm. -- (Press monograph ; 184) Includes bibliographical references and index. ISBN 978-0-8194-7245-8 1. Radiation--Measurement. I. Grant, Barbara G. (Barbara Geri), 1957- II. Title. QD117.R3P35 2009 539.7'7--dc22 2009038491
Published by SPIE P.O. Box 10 Bellingham, Washington 98227-0010 USA Phone: +1 360.676.3290 Fax: +1 360.647.1445 Email:
[email protected] Web: http://spie.org Copyright © 2010 Society of Photo-Optical Instrumentation Engineers (SPIE) All rights reserved. No part of this publication may be reproduced or distributed in any form or by any means without written permission of the publisher. The content of this book reflects the work and thought of the author(s). Every effort has been made to publish reliable and accurate information herein, but the publisher is not responsible for the validity of the information or for any outcomes resulting from reliance thereon. Printed in the United States of America. On the cover: A Crooke radiometer and the equation of radiative transfer.
Contents Foreword ................................................................................................... xi Preface .................................................................................................... xiii
Chapter 1 Introduction to Radiometry / 1 1.1 Definitions............................................................................................ 1 1.2 Why Measure Light?............................................................................ 2 1.3 Historical Background.......................................................................... 4 1.4 Radiometric Measurement Process .................................................... 5 1.5 Radiometry Applications...................................................................... 7 References ................................................................................................ 9
Chapter 2 Propagation of Optical Radiation / 11 2.1 Basic Definitions ................................................................................ 11 2.1.1 Rays and angles.................................................................... 11 2.1.2 System parameters ............................................................... 19 2.1.3 Optical definitions .................................................................. 23 2.2 Fundamental Radiometric Quantities ................................................ 24 2.2.1 Radiance ............................................................................... 24 2.2.2 Radiant exitance.................................................................... 26 2.2.3 Irradiance .............................................................................. 28 2.2.4 Radiant intensity .................................................................... 29 2.3 Radiometric Approximations.............................................................. 30 2.3.1 Inverse square law ................................................................ 30 2.3.2 Cosine3 law ........................................................................... 31 2.3.3 Lambertian approximation ..................................................... 32 2.3.4 Cosine4 law ........................................................................... 33 2.4 Equation of Radiative Transfer .......................................................... 36 2.5 Configuration Factors ........................................................................ 38 2.6 Effect of Lenses on Power Transfer .................................................. 40 2.7 Common Radiative Transfer Configurations ..................................... 42 2.7.1 On-axis radiation from a circular Lambertian disc ................. 42 2.7.2 On-axis radiation from a non-Lambertian disc ...................... 43 2.7.3 On-axis radiation from a spherical Lambertian source .......... 44 2.8 Integrating Sphere ............................................................................. 46 2.9 Radiometric Calculation Examples.................................................... 48 2.9.1 Intensities of a distant star and the sun ................................. 48 v
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Contents
2.9.2 Lunar constant....................................................................... 50 2.9.2.1 Calculation ..................................................................... 50 2.9.2.2 Moon–sun comparisons ................................................. 51 2.9.3 “Solar furnace”....................................................................... 52 2.9.4 Image irradiance for finite conjugates ................................... 53 2.9.5 Irradiance of the overcast sky ............................................... 55 2.9.6 Near extended source ........................................................... 55 2.9.7 Projection system .................................................................. 56 2.10 Generalized Expressions for Image-Plane Irradiance ..................... 57 2.10.1 Extended source ................................................................... 57 2.10.2 Point source .......................................................................... 58 2.11 Summary of Some Key Concepts ................................................... 58 For Further Reading ................................................................................ 59 References .............................................................................................. 59
Chapter 3 Radiometric Properties of Materials / 61 3.1 Introduction and Terminology ............................................................ 61 3.2 Transmission ..................................................................................... 62 3.3 Reflection .......................................................................................... 63 3.4 Absorption ......................................................................................... 69 3.5 Relationship Between Reflectance, Transmittance, and Absorptance ...................................................................................... 69 3.6 Directional Characteristics ................................................................. 69 3.6.1 Specular transmittance and reflectance ................................ 69 3.6.2 Diffuse transmittance and reflectance ................................... 73 3.7 Emission ............................................................................................ 76 3.8 Spectral Characteristics .................................................................... 77 3.9 Optical Materials Checklist ................................................................ 79 For Further Reading ................................................................................ 80 References .............................................................................................. 80
Chapter 4 Generation of Optical Radiation / 83 4.1 Introduction ........................................................................................ 83 4.2 Radiation Laws .................................................................................. 84 4.2.1 Planck’s law........................................................................... 84 4.2.2 Wien displacement law.......................................................... 86 4.2.3 Stefan-Boltzmann law ........................................................... 89 4.2.4 Laws in photons .................................................................... 89 4.2.5 Rayleigh-Jeans law ............................................................... 92 4.2.6 Wien approximation ............................................................... 93 4.2.7 More on the Planck equation................................................. 93 4.2.8 Kirchhoff’s law ....................................................................... 97 4.3 Emitter Types and Properties .......................................................... 102 4.3.1 Metals .................................................................................. 102
Contents
vii
4.3.2 Dielectrics ............................................................................ 102 4.3.3 Gases .................................................................................. 103 4.4 Practical Sources of Radiant Energy............................................... 104 4.4.1 Two major categories .......................................................... 104 4.4.2 Thermal sources.................................................................. 105 4.4.2.1 Tungsten and tungsten-halogen lamps ........................ 105 4.4.2.2 Other metallic sources.................................................. 108 4.4.2.3 Dielectric thermal sources ............................................ 108 4.4.2.4 Optical elements........................................................... 109 4.4.2.5 Miscellaneous thermal sources .................................... 109 4.4.3 Luminescent sources .......................................................... 110 4.4.3.1 General principles ........................................................ 110 4.4.3.2 Fluorescent lamps ........................................................ 115 4.4.3.3 Electroluminescent sources ......................................... 117 4.4.3.4 LED sources ................................................................. 117 4.4.3.5 Lasers .......................................................................... 118 4.4.4 Natural sources ................................................................... 119 4.4.4.1 Sunlight ........................................................................ 119 4.4.4.2 Skylight, planetary, and astronomical sources ............. 120 4.4.4.3 Application: energy balance of the earth ...................... 121 4.5 Radiation Source Selection Criteria................................................. 121 4.6 Source Safety Considerations ......................................................... 123 4.7 Summary of Some Key Concepts ................................................... 123 For Further Reading .............................................................................. 123 References ............................................................................................ 124
Chapter 5 Detectors of Optical Radiation / 127 5.1 Introduction...................................................................................... 127 5.2 Definitions ........................................................................................ 128 5.3 Figures of Merit ............................................................................... 131 5.4 #N$O%&I*S@E~^ ........................................................................... 133 5.4.1 Introduction to noise concepts............................................. 133 5.4.2 Effective noise bandwidth.................................................... 136 5.4.3 Catalog of most unpleasant noises ..................................... 137 5.4.3.1 Johnson noise .............................................................. 137 5.4.3.2 Shot noise .................................................................... 139 5.4.3.3 1/f noise ........................................................................ 139 5.4.3.4 Generation-recombination noise .................................. 140 5.4.3.5 Temperature fluctuation noise ...................................... 141 5.4.3.6 Photon noise ................................................................ 141 5.4.3.7 Microphonic noise ........................................................ 142 5.4.3.8 Triboelectric noise ........................................................ 142 5.4.3.9 CCD noises .................................................................. 142 5.4.3.10 Amplifier noise .............................................................. 143 5.4.3.11 Quantization noise........................................................ 143
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5.4.4 Noise factor, noise figure, and noise temperature ............... 143 5.4.5 Some noise examples ......................................................... 144 5.4.6 Computer simulation of Gaussian noise.............................. 147 5.5 Thermal Detectors ........................................................................... 147 5.5.1 Thermal circuit ..................................................................... 147 5.5.2 Thermoelectric detectors ..................................................... 150 5.5.2.1 Basic principles ............................................................ 150 5.5.2.2 Combinations and configurations ................................. 153 5.5.3 Thermoresistive detector: bolometer ................................... 155 5.5.4 Pyroelectric detectors .......................................................... 157 5.5.4.1 Basic principles ............................................................ 157 5.5.4.2 Pyroelectric materials ................................................... 160 5.5.4.3 Operational characteristics of pyroelectric detectors ... 162 5.5.4.4 Applications of pyroelectric detectors........................... 162 5.5.5 Other thermal detectors....................................................... 163 5.6 Photon Detectors ............................................................................. 164 5.6.1 Detector materials ............................................................... 164 5.6.2 Photoconductive detectors .................................................. 169 5.6.2.1 Basic principles ............................................................ 169 5.6.2.2 Noises in photoconductive detectors ........................... 173 5.6.2.3 Characteristics of photoconductive detectors .............. 174 5.6.2.4 Applications of photoconductive detectors ................... 175 5.6.3 Photoemissive detectors ..................................................... 175 5.6.3.1 Basic principles ............................................................ 175 5.6.3.2 Classes of emitters....................................................... 176 5.6.3.3 Dark current ................................................................. 181 5.6.3.4 Noises in photoemissive detectors ............................... 182 5.6.3.5 Photoemissive detector types ...................................... 183 5.6.4 Photovoltaic detectors ......................................................... 185 5.6.4.1 Basic principles ............................................................ 185 5.6.4.2 Responsivity and quantum efficiency ........................... 195 5.6.4.3 Noises in photovoltaic detectors .................................. 196 5.6.4.4 Photovoltaic detector materials and configurations ...... 198 5.7 Imaging Arrays ................................................................................ 199 5.7.1 Introduction.......................................................................... 199 5.7.2 Photographic film................................................................. 199 5.7.2.1 History .......................................................................... 199 5.7.2.2 Physical characteristics ................................................ 201 5.7.2.3 Spectral sensitivity ....................................................... 201 5.7.2.4 Radiometric calibration................................................. 201 5.7.2.5 Spatial resolution.......................................................... 202 5.7.2.6 Summary ...................................................................... 202 5.7.3 Electronic detector arrays.................................................... 203 5.7.3.1 History .......................................................................... 203 5.7.3.2 Device architecture description and tradeoffs .............. 203
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ix
5.7.3.3 Readout mechanisms .................................................. 204 5.7.3.4 Comparison .................................................................. 207 5.7.4 Three-color CCDs ............................................................... 207 5.7.5 Ultraviolet photon-detector arrays ....................................... 208 5.7.6 Infrared photodetector arrays .............................................. 209 5.7.7 Uncooled thermal imagers .................................................. 210 5.7.8 Summary ............................................................................. 211 For Further Reading .............................................................................. 211 References ............................................................................................ 213
Chapter 6 Radiometric Instrumentation / 215 6.1 Introduction...................................................................................... 215 6.2 Instrumentation Requirements ........................................................ 215 6.2.1 Ideal radiometer .................................................................. 215 6.2.2 Specification sheet .............................................................. 215 6.2.3 Spectral considerations ....................................................... 216 6.2.4 Spatial considerations ......................................................... 217 6.2.5 Temporal considerations ..................................................... 217 6.2.6 Make or buy?....................................................................... 218 6.3 Radiometer Optics........................................................................... 218 6.3.1 Introduction.......................................................................... 218 6.3.2 Review of stops and pupils.................................................. 218 6.3.3 The simplest radiometer: bare detector ............................... 219 6.3.4 Added aperture.................................................................... 219 6.3.5 Basic radiometer ................................................................. 221 6.3.6 Improved radiometer ........................................................... 223 6.3.7 Other methods for defining the field of view ........................ 224 6.3.8 Viewing methods ................................................................. 224 6.3.9 Reference sources .............................................................. 226 6.3.10 Choppers ............................................................................. 226 6.3.11 Stray light ............................................................................ 227 6.3.12 Summing up ........................................................................ 228 6.4 Spectral Instruments ....................................................................... 228 6.4.1 Introduction.......................................................................... 228 6.4.2 Prisms and gratings............................................................. 230 6.4.3 Monochromator configurations ............................................ 231 6.4.4 Spectrometers ..................................................................... 234 6.4.5 Additive versus subtractive dispersion ................................ 235 6.4.6 Arrays .................................................................................. 236 6.4.7 Multiple slit systems ............................................................ 236 6.4.8 Filters................................................................................... 236 6.4.9 Interferometers .................................................................... 237 6.4.10 Fourier transform infrared.................................................... 237 6.4.11 Fabry-Perot ......................................................................... 238
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Contents
For Further Reading .............................................................................. 240 References ............................................................................................ 240
Chapter 7 Radiometric Measurement and Calibration / 241 7.1 Introduction ...................................................................................... 241 7.2 Measurement Types ........................................................................ 241 7.3 Errors in Measurements, Effects of Noise, and Signal-to-Noise Ratio in Measurements ............................................................................. 241 7.4 Measurement and Range Equations ............................................... 250 7.5 Introduction to the Philosophy of Calibration ................................... 253 7.6 Radiometric Calibration Configurations ........................................... 257 7.6.1 Introduction.......................................................................... 257 7.6.2 Distant small source ............................................................ 258 7.6.3 Distant extended source...................................................... 260 7.6.4 Near extended source ......................................................... 261 7.6.5 Near small source ............................................................... 262 7.6.6 Direct method ...................................................................... 262 7.6.7 Conclusion........................................................................... 263 7.7 Example Calculations: Satellite Electro-optical System .................. 263 7.8 Final Thoughts ................................................................................. 267 For Further Reading .............................................................................. 268 References ............................................................................................ 268
Table of Appendices / 269 Appendix A: Système Internationale (SI) Units for Radiometry and Photometry ....................................................................... 271 Appendix B: Physical Constants, Conversion Factors, and Other Useful Quantities.......................................................................... 275 Appendix C: Antiquarian’s Garden of Sane and Outrageous Terminology ...................................................................... 277 Appendix D: Solid-Angle Relationships ................................................. 283 Appendix E: Glossary............................................................................ 285 Appendix F: Effective Noise Bandwidth of Analog RC Filters and the Selection of Filter Parameters to Optimize Signal-to-Noise Ratio ................................................................................. 297 Appendix G: Bandwidth Normalization by Moments ............................. 305 Appendix H: Jones Near-Small-Source Calibration Configuration ........ 309 Appendix I: Is Sunglint Observable in the Thermal Infrared? .............. 313 Appendix J: Documentary Standards for Radiometry and Photometry 321 Appendix K: Radiometry and Photometry Bibliography ........................ 341 Appendix L: Reference List for Noise and Postdetection Signal Processing ........................................................................ 357
Index / 361
Foreword The material for this book grew out of a first-year graduate-level course, “Radiometry, Sources, Materials, and Detectors,” that Jim Palmer created and taught at the University of Arizona College of Optical Sciences for many years. The book is organized by topic in a similar manner, with the first five chapters presenting radiation propagation and system building blocks, and the final two chapters focusing on instruments and their uses. Chapter 1 provides an overview and history of the subject, and Chapter 2 presents basic concepts of radiometry, including terminology, laws, and approximations. It also includes examples that will allow the reader to see how key equations may be used to address problems in radiation propagation. Chapter 3 introduces radiometric properties of materials such as reflection and absorption, and Chapter 4 extends that discussion via a detailed consideration of sources. Point and area detectors of optical radiation are considered in Chapter 5, which also includes thermal and photon detection mechanisms, imaging arrays, and a discussion about film. In Chapter 6, the focus shifts to instrumentation. Concepts introduced in Chapter 2 are here applied to instrument design. Practical considerations relating to radiometer selection are detailed, and a “Make or Buy?” decision is explored. Several monochromator configurations are examined, and spectral instruments are discussed. Proceeding from instruments to their uses, Chapter 7 details types of measurements that may be made with radiometric systems and provides a discussion of measurement error. The philosophy of calibration is introduced, and several radiometric calibration configurations are considered. The material in the appendices covers a variety of topics, including terminology, standards, and discussions of specific issues such as Jones source calibration and consideration of solar glint. Due to Jim’s attention to detail and the length of time over which he accumulated material, the long lists he provided here may be viewed as comprehensive, if not current by today’s standards. The level of discussion of the material is suitable for a class taught to advanced undergraduate students or graduate students. The book will also be useful to the many professionals currently practicing in fields in which radiometry plays a part: optical engineering, electro-optical engineering, imagery analysis, and many others. In 2006, Jim Palmer was told that he was terminally ill, and he asked me to complete this work. I was humbled and honored by the request. I’d met Jim as a graduate student in optical sciences in the late 1980s, and he had served on my thesis committee. My career after graduation had focused on systems engineering and analysis, two areas in which radiometry plays a significant role. For nearly the last ten years of Jim’s life, I’d been able to receive mentoring from the master simply by showing up at Jim’s office door with a question or topic for discussion, but I never anticipated that our discussions would one day come to an end. Upon Jim’s death, I sought to weave his collection of resources and narrative together xi
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Forward
with newer material and discussion in a manner I hope will be both informative to read and valuable to reference. The preface that follows was written by Jim before he died and has been left as he wrote it. I am grateful for the assistance of many. First is William L. Wolfe, Jim’s professor and mentor, who offered helpful comments on each chapter and adapted Chapter 6 on radiometric instrumentation. Others for whose help I am grateful, all from or associated with the University of Arizona College of Optical Sciences, are Bob Schowengerdt, who contributed the narrative on film; Anurag Gupta of Optical Research Associates, Tucson, Arizona, who adapted the appendix material; and L. Stephen Bell, Jim’s close friend and colleague, who revised the signal processing discussion that appears in that section and provided a complete bibliography on the subject. A special note of thanks goes to Eustace Dereniak, who provided office space for me, helpful discussions, and hearty doses of encouragement. I also wish to thank John Reagan, Kurt Thome (NASA Goddard Spaceflight Center, Greenbelt, Maryland), Mike Nofziger, and Arvind Marathay for review, discussion, and helpful insights. In addition, I am grateful for the assistance of Anne Palmer, Jim’s beloved sister, and University of Arizona College of Optical Sciences staff members Trish Pettijohn and Ashley Bidegain. Gwen Weerts and Tim Lamkins of SPIE Press have my gratitude for the special assistance they provided to this project. I also gratefully acknowledge Philip N. Slater, my professor in optical sciences, who selected me as a graduate student and trained me in remote sensing and absolute radiometric calibration from 1987 to 1989, and Michael W. Munn, formerly Chief Scientist at Lockheed Martin Corporation, who instilled the value of a systems perspective in the approach to technical problems. Finally, I am grateful to my family for providing financial support; to Ralph Gonzales, Arizona Department of Transportation, and Sylvia Rogers Gibbons for providing professional contacts; and my friends at Calvary Chapel, Tucson, Arizona, whose donations and prayers sustained me as I worked to complete this book. Barbara G. Grant Cupertino, California October 2009
Preface This volume is the result of nearly twenty years of frustration in locating suitable material for teaching the subject of radiometry and its allied arts. This is not to say that there is not a lot of good stuff out there—it’s just not all in one place, consistent in usage of units, and applicable as both a teaching tool and as a reference. I intend this book to be all things to all people interested in radiometry. The material comes from teaching both undergraduate and graduate-level courses at the Optical Sciences Center of the University of Arizona, and from courses developed for SPIE and for industrial clients. I have unabashedly borrowed the tenor of the title from the superb text The Art of Electronics by Paul Horowitz in the hope that this volume will be as useful to the inquisitive reader. I gratefully acknowledge the contributions of my mentor, William L. Wolfe, Jr., and the hundreds of students whose constant criticism and occasional faint praise have helped immeasurably. This book is dedicated to the memory of my mother, Candace W. Palmer (1904–1996) and my father, James A. Palmer (1905–1990). She was all one could wish for in a Mom, and he showed me the path to engineering. James M. Palmer 1937–2007
xiii
Chapter 1
Introduction to Radiometry 1.1 Definitions Consider the following definitions a starting point for our study of radiometry: radio- [> 1 . Then, the 1 can be dropped and the equation becomes: Lλ =
−c
c1 λT2 e πλ 5
(4.19)
The Wien approximation is valid with less than 1% error if λT < 3000 μm·K (short wavelengths and/or low temperatures). It is quite useful for a great deal of radiometric work as it is valid for blackbody radiation at all wavelengths shorter than the peak. Figures 4.5 and 4.6 depict the curves and the ranges of validity for the two approximations. 4.2.7 More on the Planck equation
A career can be spent fiddling with the Planck equation, presenting it for various frequencies, wavenumbers, etc. We will keep it simple and just do some normalization. Divide both sides of the Planck equation by T5: Lλ c1 1 = . T 5 π(λT )5 ec2 / λT − 1
(4.20)
(μm·K) Figure 4.5 Wien and Rayleigh-Jeans blackbody approximation curves.
94
Chapter 4
(μm-K) Figure 4.6 Errors associated with Wien and Rayleigh-Jeans approximations.
The result is an expression which is now a function of a new variable, (λΤ ). The result of this normalization is a single curve as shown in Fig. 4.7 for Planckian radiation for any wavelength and temperature. The Planck function can also be normalized by dividing by Lλmax such that the resulting curve peaks at unity. This curve is denoted as f(λT). An additional very useful curve shows the cumulative (integrated) radiance from 0 up to λT divided by the total radiance at temperature T. This cumulative curve is labeled F(λT). The defining equations for these two functions are: f (λ T ) = and
Lλ (λT ) L (λT ) = λ σ' 5 Lλ (λ maxT ) T π
λ
F (λT ) =
Lλ (λT )d λ
0 ∞
L (λT ) d λ λ
0
(4.21)
λ
L (λT ) d λ λ
=
0
σ 4 T π
.
(4.22)
Generation of Optical Radiation
95
5E-12
RADIANCE/T^5
4E-12 3E-12 2E-12 1E-12 0 0
5000 10000 WAVELENGTH x TEMPERATURE (um-K)
15000
Figure 4.7 Normalization of the Planck curve.
Since these definitions are ratios, exitance M can readily be substituted for radiance L. These two functions are graphed in Fig. 4.8. To use these curves to determine radiance in a narrow wavelength interval (Δλ < 0.05λc), first select T for the blackbody radiation and the desired center wavelength λc. Determine the radiance at the peak using the equation for Lλ(max). Finally, use the function f(λT) from the graph and the wavelength interval Δλ to arrive at the result λ c +Δλ / 2
Lλ (λT )d λ = Lλ (λ maxT ) f (λ cT )Δλ .
(4.23)
λ c −Δλ / 2
If the wavelength interval is large, typically greater than 0.05× the center wavelength, use the other function F(λT) to determine the radiance in a finite wavelength interval. Again select T and the two desired wavelengths, λ1 and λ2. From the graph, read F(λ1T) and F(λ2T) and compute the total radiance using the Stefan-Boltzmann law. The result is λ2
σ L (λT ) d λ = π T [ F (λ T ) − F (λ T ) ] 4
λ
2
1
λ2 > λ1.
(4.24)
λ1
Figure 4.8 also shows the corresponding curves for photons, fq(λT) and Fq(λT). The defining equations are
96
Chapter 4
Figure 4.8 Curves of f(λ) and F(λ) for watts and photons.
f q ( λT ) =
Lqλ ( λT )
(4.25)
Lqλ ( λ maxT )
and λ
Fq (λT ) =
Lqλ (λT )d λ
0 ∞
L
qλ
0
(λT ) d λ
λ
L
qλ
=
0
(λ T ) d λ
σq π
. T
(4.26)
3
The application of the fq and Fq photon curves is identical to the curves for energy. In some applications, it is desirable to maximize the radiation contrast between a target and background of similar temperature. What wavelength might one choose for this task? The problem occurs regularly in the infrared where both the target and the background radiate near 300 K. Take the second derivative d2Lλ/(dTdλ), and set it to zero. The result is:
λ contrast T = 2411 μm ⋅ K .
(4.27)
This equation implies that the best “visibility,” or contrast with the background, occurs at a wavelength somewhat shorter than the peak wavelength, at λcontrast = 0.832λmax. Since the result is on the short wavelength side of the peak, the Wien approximation is valid and it simplifies the calculus considerably.
Generation of Optical Radiation
97
Thus, if your target and background temperature were 305 K, the peak wavelength is 9.50 μm and the wavelength of maximum radiation contrast λcontrast is 7.9 μm. The wavelength for maximum photon contrast is 2898 μm·K, the same as the peak wavelength for energy. We often need to know how the spectral radiance Lλ changes with temperature; this can be determined by differentiating the Planck function with respect to temperature. The result, shown in differential form, is ΔLλ xe x ΔT = x , Lλ e −1 T
(4.28)
c hc = 2 . λkT λT xe x . For a small change in temperature ΔT such that the We define Z ≡ x e −1 change in x is also small, the change in Lλ with temperature at any wavelength is
where x =
ΔLλ ΔT =Z . Lλ T
(4.29)
If ex is significantly greater than unity (λT T1, a current will flow around the loop in the direction indicated. The current’s magnitude will be proportional to ΔT = (T2 – T1); its exact value depends upon the resistance of the circuit and the difference between the thermoelectric powers of the two metals. This phenomenon is called the Seebeck effect, named after its discoverer, T. J. Seebeck (1821). Opening the circuit, as shown in Fig. 5.13, and measuring the voltage results in the following relationship: S=
ΔV (V/deg), ΔT
(5.47)
where S = the Seebeck coefficient, or, alternatively, thermoelectric power. The open-circuit voltage is SΔT.
METAL 1
J1@T1
I
J2@T2
METAL 2 6 Figure 5.12 Thermoelectric circuit. [Reprinted from Optical Radiation Measurement series, Vol. 4, W. Budde, Physical Detectors of Optical Radiation, p. 101 (1983).]
Detectors of Optical Radiation
151
METAL 1
J1@T1
J2@T2
METAL 2
J3@T3
J4@T3
METAL 3
METAL 2
METAL 3 V 6
Figure 5.13 Open-circuit thermoelectric pair. [Reprinted from Optical Radiation Measurement series, Vol. 4, W. Budde, Physical Detectors of Optical Radiation, p. 101 (1983).]
In this case, an additional pair of metal wires represents a voltage-measuring instrument inserted into the circuit. These wires are typically made of copper. Two additional junctions, J3 and J4, are formed, whose thermoelectric contributions cancel out if they are at the same temperature, according to the law of intermediate materials commonly applied in mechanical engineering. In addition, if the wires are homogeneous, the voltage depends only on the temperatures of the junctions, and not on temperature distributions along the wires. In 1834, Jean C. A. Peltier experimented with thermoelectric circuits by passing currents through them. He noted that one of the junctions became warm, while the other cooled. The coefficient describing the magnitude of this effect is called the Peltier coefficient. It is expressed as: 1 dQ Π= , I dt
(5.48)
where dQ/dt is heat flow and I is current. This effect is exploited in thermoelectric coolers, which are used to cool detectors, laser diodes, small refrigerators, dew-point sensors, and many other things. The Peltier coefficient is related to the Seebeck coefficient by the second kelvin relationship, Π = T × S, where T is absolute temperature in degrees kelvin. This second-order effect occurs in opposition to the Seebeck effect; that is, a current flow due to a change in temperature causes a reduction in that temperature change. It is thus undesirable in radiation detectors, in which it is desirable to maximize ΔT for optimum sensitivity. Hence, such detectors are usually operated with little or no current flow. Signals from thermal detectors can be increased by placing several junction pairs in series, connecting alternate junctions to blackened receivers exposed to incoming radiation, and connecting the other junctions to heat sinks. Devices
152
Chapter 5
using multiple thermocouple junctions are called thermopiles and are used in most thermoelectric transducers. Some of the theory behind thermoelectric detectors can help to understand their operation. Going back to the thermal equations common to all detectors, we have ΔT = αΦRT
(dc case)
(5.49)
and ΔT =
α ΦRT
(ac case).
1 + ω2 τT 2
(5.50)
Neglecting Peltier cooling, the responsivities are given by ℜ = αSRT
(dc case)
(5.51)
and ℜ(ω) =
α SRT
1 + ω2 τT 2
(ac case).
(5.52)
If current is permitted to flow, the Peltier effect causes a reduction in sensitivity. In that case, ΔΤ is given by R S 2Td ΔT = αΦRT 1 − T , R
(5.53)
where unsubscripted R is the electrical resistance. Since thermocouples are purely resistive, the limiting noise is Johnson noise in the resistance R. Performance can thus be enhanced somewhat by cooling. It can also be enhanced by reducing the value of R; however, this results in decreased RT as well. The overall effect is to decrease thermal sensitivity ΔΤ. A better solution is to use materials having low electrical resistance and high thermal resistance, but for most metals this is not much of an option. Instead, we choose materials for their thermoelectric properties and then optimize either speed or sensitivity, depending upon application. Table 5.7 lists common thermoelectric materials, along with their thermoelectric power values.
Detectors of Optical Radiation
153
Table 5.7 Thermoelectric materials and thermoelectric power values.
Material
S (μV/°C)
Material
S (μV/°C)
Al Cu Ag Fe Constantan
-0.5 +2.7 +2.9 +16 38
Bi Sb Si Ge
-60 +40 -400* +300*
*
variable, depends on doping
5.5.2.2 Combinations and configurations
There are many material combinations that furnish useful thermoelectric pairs, the majority of which are designed for industrial thermometry over wide temperature ranges. Constantan, for example, is an alloy of copper and nickel developed specifically for thermoelectric measurement. It is paired with copper or iron to form the popular type J and T thermocouples, respectively. The type T thermocouple has an output voltage of approximately 40 μV for a 1° C difference between the hot and cold junction. Seebeck worked with bismuth-antimony (BiSb) pairs. These have the highest thermoelectric power for any of the commonly used metals, 100 μV/°C for the pair. Specially doped silicon and germanium yield the highest output but are difficult to fabricate. Four distinct configurations for thermocouple/thermopile radiation detectors are shown in Fig. 5.14. All early thermopiles were fabricated by soldering or welding fine wires (usually Bi-Sb), culminating with the Coblentz designs [Fig. 5.14(a)]. The linear models are still used for large spectroscopic detectors and the circular for laser power meters and radiometry. The Schwarz design [Fig. 5.14(b)] features two pins of doped Si and Ge, connected by a 0.3-μm-thick blackened gold foil. They are extensively used for small spectroscopic detectors. A wirewound thermopile [Fig. 5.14(c)] can be fabricated by winding many turns of Constantan wire onto a thin insulator and electroplating silver on half of it. The junctions are not very efficient, but they are easy to fabricate. More recent thermopile designs have been realized by vacuum evaporation of alternating layers of bismuth and antimony onto a substrate [Fig. 5.14(d)]. One example utilizes a thin Mylar™ substrate placed over an insulating channel. The thickness of the Mylar determines the speed/responsivity tradeoff for a given application. Another example utilizes micromachined silicon with a thin oxide layer (vanadium oxide for example) or aluminum to create monolithic structures used for thermal imaging. Typical characteristics for both wirewound and evaporated thermopile detectors are shown in Table 5.8.
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Figure 5.14 Thermopile configurations: (a) Coblentz, (b) Schwartz (c) wirewound, and (d) evaporated.7 [Reprinted from Semiconductors and Semimetals series, Vol. 5, N. B. Stevens, “Radiation Thermopiles,” pp. 300–304 (1970).] Table 5.8 Characteristics of wirewound and evaporated thermopile detectors.
Parameter
Wirewound
Evaporated
Active area
1 × 3 mm to 1 × 10 mm
0.5 × 0.5 mm to 4 × 4 mm
NEP
0.1 to 1 n·W/Hz1/2
0.3 to 1 n·W/Hz1/2
D*
108 to 109 cm·Hz1/2/W
1 to 3 × 108 cm·Hz1/2/W
Time constant
4 to 400 ms
25 to 100 ms
Responsivity
0.1 to 10 V/W
10 to 50 V/W
Resistance
10 Ω to 2 kΩ
2 to 20 kΩ
Spectral range
0.3 to 100 μm
0.3 to 30 μm
Window materials
SiO2, KRS-5
BaF2, CaF, KBr
Filter types
Long-wave pass, bandpass
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Table 5.9 Some applications of thermopile detectors.
Passive intrusion alarms Spectral gas analyzers Flame detection Radiometry—laser, spectral, and broadband IR thermometry Thermopile detectors are extremely versatile due to their small size, low cost, and wide wavelength range of operation at dc and room temperature. They can be ruggedized to survive space applications such as horizon sensing and earth radiation budget measurements. Some terrestrial uses of thermopile detectors are shown in Table 5.9. 5.5.3 Thermoresistive detector: bolometer
When a thermoresistive material absorbs incident radiation, it becomes warmer and its electrical resistance changes. The resistance change can be sensed using a device called a bolometer, first invented by S. P. Langley in 1880. The bolometer is a resistor that possesses a high temperature coefficient of resistance, often abbreviated as TCR and symbolized here as β, with units of K–1 . Bolometers are fabricated from metals (the classical approach) and semiconductors (modern). General characteristics of resistance as a function of temperature for both material types are shown in Fig. 5.15. The equation for resistance as a function of temperature is
R(T ) = Ro (1 + βΔT ) ,
(5.54)
where β = (1/R)(dR/dT) and Ro is the resistance at some nominal temperature, often 25° C.
R METAL
SEMI
T Figure 5.15 General characteristics of resistance as a function of temperature for metal and semiconductor materials used in bolometers.
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Chapter 5
As can be seen from Eq. (5.54), the change in resistance ΔR is proportional to RoβΔT, where ΔT may be obtained using Eq. (5.37). Note that the resistances referred to above are electrical, not to be confused with RT, a material’s thermal resistance described earlier in the chapter. For metals, β is quite small, on the order of 0.5%/°C. These bolometers are rather insensitive. For the semiconducting materials, mixed oxides called thermistors, β is proportional to T–2, making them potentially quite sensitive. In order for a resistance to be measured, we must force a current through the circuit and measure a voltage drop. Although many circuit types may be used, the half-bridge circuit depicted in Fig. 5.16 is the most popular. A voltage source drives two resistors in series, with the upper resister the load resistor, and the lower resistor the bolometer itself. A coupling capacitor (C) is frequently used to block the dc signal across the sensitive component, RB. This is necessary due to the sensitivity of the component to dc voltage. As a result, modulated beams are required for successful operation of the circuit. The expression for signal voltage measured across the terminals is Vs = ΔV =
VB RL ΔRB . ( RB + RL ) 2
(5.55)
Taking a page from electrical engineering, we invoke the maximum power transfer theorem to set RL equal to RB. Then, Vs = ΔV =
VB RΔR VB ΔR VB RoβΔT = = ( R + R) 2 4 R 4 R
Figure 5.16 Bolometer half-bridge circuit.
.
(5.56)
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Substituting for ΔT from Eq. (5.50) and recognizing that for small ΔT, R~Ro, the bolometer voltage responsivity ℜv is ℜv =
Vs VB = Φ 4
αβRT 1 + ω2 τT 2
.
(5.57)
Inspection of this equation shows that to maximize the responsivity, we should make RT as large as possible. However, by Eq. (5.38), this also increases τT, making the device slower. Thus, we have a tradeoff between responsivity and speed. Because responsivity varies linearly with bias voltage VB, we may consider increasing the bias voltage. This also increases the current through the bolometer, which heats it. Increased heating is typically not a problem in metal bolometers, but can lead to thermal runaway and burnout in thermistor bolometers. A constant current bias can prevent burnout, but the additional electronics add noise to the circuit, making this approach unattractive unless wide variations in ambient temperature are encountered. A better solution is to make the load resistor a matched bolometer element and shield it from the incident radiation. Because the bolometer is a resistive device, Johnson noise predominates. If the electrical contacts are less than perfect, we can also get 1/f noise. The ultimate performance limit for the device, in which temperature fluctuation noise predominates, is rarely seen until the device temperature approaches 4 K. Typical room temperature bolometers exhibit D* values on the order of 109 cm·Hz1/2/W, with responsivities varying between 10 and 104 V/W depending on the material and temperature, with time constants varying between 1 and 100 milliseconds, depending upon the size of the bolometer element. (Uncooled microbolometer arrays, part of a relatively recent development in thermal imaging, feature thermal time constants of a few milliseconds.) Cooling the bolometer to cryogenic temperatures increases the D* to 1012 cm·Hz1/2/W at 2 K and 1016 cm·Hz1/2/W at 0.1 K. Bolometers used at these temperatures are typically fabricated from germanium (the Low bolometer) or composite materials. Another interesting variant is the superconducting bolometer, which operates at the superconductor transition temperature. It is extremely sensitive but has limited dynamic range, even with active bias control. 5.5.4 Pyroelectric detectors 5.5.4.1 Basic principles
The pyroelectric detector is unusual in that it is capable of high-speed operation and responds only to changing signals. The pyroelectric effect was first suggested for radiation detection by Yeou Ta in 1938. Certain ferroelectric materials with asymmetric crystal orientations display the pyroelectric effect, which is a change in surface charge (spontaneous polarization) with temperature. The effect is not
158
Chapter 5
observed at constant temperature as mobile charges within the material align to maintain neutrality. The pyroelectric coefficient p is the change in electric polarization per change in temperature: p=
dPs C/cm2K, dT
(5.58)
where dPs is the change in polarization. The pyroelectric coefficient increases with temperature as shown in Fig. 5.17 until the Curie temperature is reached, when it abruptly drops to zero with attendant loss of response. Fortunately, this is not usually a permanent condition, and the device can often be reactivated. The equivalent circuit is shown in Fig. 5.18(b) as a current generator in parallel with a capacitor and a shunt (or load) resistance RL. A change in temperature ΔT produces a charge Q such that
Q = pAd ΔT ,
(5.59)
where Ad = the sensitive area of the detector and p = the pyroelectric coefficient. The pyroelectric current ip is the product of radian frequency ω and charge: i p = ωQ = ωpAd ΔT .
(5.60)
6 Figure 5.17 Pyroelectric coefficient versus temperature. [Reprinted from Optical Radiation Measurement series, Vol. 4, W. Budde, Physical Detectors of Optical Radiation, p. 129 (1983).]
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Figure 5.18 (a) Initial circuit and (b) equivalent circuit of a pyroelectric detector, with the 8 current generator in parallel with a capacitor and load resistor. [Reprinted from Semiconductors and Semimetals series, Vol. 5, E. Putley, “The Pyroelectric Detector” (1970).]
The current responsivity for the pyroelectric detector may be found by inserting the expression for ΔT in Eq. (5.37) and substituting the expression for τT in Eq. (5.38): ℜi =
ip Φ
=
ωpAd ΔT ωpAd αRT ωpAd αRT = = , Φ 1 + ω2 RT 2 H 2 1 + ω2 τT 2
(5.61)
where τT is the thermal time constant. To determine the output voltage across a load resistor, RL in Fig. 5.18, recall that the output voltage signal is the product of current and impedance.9 In this case, the output voltage is given by v=
i p RL
1 + ω2 RL 2C 2
,
(5.62)
where RLC = the circuit’s electrical time constant τ and ip is given by Eq. (5.60). Therefore, the expression for voltage may be rewritten as v=
ωpAd ΔTRL
1 + ω2 τ2
.
(5.63)
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Chapter 5
Figure 5.19 Voltage responsivity as a function of radian frequency.8 [Reprinted from Semiconductors and Semimetals series, Vol. 5, E. Putley, "The Pyroelectric Detector" (1970).].
Substituting for ΔT from Eq. (5.37) and applying the definition of thermal time constant, the voltage responsivity may be expressed as ℜv =
αωpAd RL RT
1 + ω2 τ2 1 + ω2 τT 2
.
(5.64)
In this case, the responsivity increases from zero to a flat region, then decreases at even higher frequencies. The width of the flat region depends upon the separation of the thermal and electrical time constants. The generic voltage responsivity behavior is shown in Fig. 5.19, while Fig. 5.20 depicts voltage responsivity as a function of electrical frequency with load resistance as the parameter. 5.5.4.2 Pyroelectric materials
Several pyroelectric materials and their properties are listed in Table 5.10. Tc is the Curie temperature and FM is a figure of merit defined as FM =
where
p , εC ′
p = the material’s pyroelectric coefficient, ε = the material’s dielectric constant, and C′ = the product of the material’s specific heat and density.
(5.65)
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Figure 5.20 Typical voltage responsivity curve for pyroelectric detectors.6 [Reprinted from Optical Radiation Measurement series, Vol. 4, W. Budde, Physical Detectors of Optical Radiation, p. 131 (1983).] Table 5.10 Pyroelectric materials and their properties.
Material
TGS
Tc (οC) 49
p (C/cm2·K) –8
4 × 10
10
9
Remarks
High D* Best D*
1500
6 × 108
Bulletproof
6 × 10–8
750
5 × 108
Fastest
2 × 10–8
1300
2 × 108
Cheap, flexible
60
LaTaO3
618
2 × 10–8
60 to 200 80
PVF2
5200
D* (cm·Hz1/2/W)
5 × 109
Doped TGS
SrBaNbO3
FM
TGS is the acronym for the organic compound triglycine sulfate. It depoles (loses its internal charge) readily, requiring the periodic or even continuous application of an electric field to maintain operation. It is also sensitive to moisture and needs protection. The D* can be enhanced by doping the material with L-alinine. SBN is strontium barium niobate, a mixture of the general form SrxBa1–xNbO3. Polyvinylidene fluoride, PVF2, is a plastic film (tradename Kynar)
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which can be cut and formed into custom configurations. Other pyroelectric materials include lead zirconate titanate (PZT), ceramic, barium titanate, and barium strontium titanate (BST). 5.5.4.3 Operational characteristics of pyroelectric detectors
The outstanding feature of the pyroelectric detector is its uniform wavelength response (depending on crystal absorption or external blackening) coupled with high sensitivity attainable without cooling. These detectors are small and require no external bias source. Several are available with built-in FET preamplifiers and matched load resistors. The impedance of the device is extremely high such that restoration of charge equilibrium is a relatively slow process. The crystal fitted with electrodes behaves like a capacitor with a variable dielectric. It can be used in either a current or voltage mode. Although the response of the pyroelectric is slow compared to photon detectors, the pyroelectric can be used in current mode for higher-speed applications when sufficient input power is available. The noises inherent in pyroelectric detectors include Johnson noise, thermal fluctuation noise, and microphonics. Pyroelectric detectors are piezoelectric and act as microphones; they must be isolated from the surrounding acoustic environment for successful operation. Preamplifiers provide an additional noise source. In terms of performance, D* values greater than 109 cm·Hz1/2/W have been achieved, as shown in Table 5.5 above, with voltage responsivities on the order of 104 V/W. If the Curie temperature is exceeded, the following procedure may be used to restore operation of the device: (1) Heat the pyroelectric element to a temperature slightly above the Curie temperature. (2) Apply a bias voltage across the electrodes. (3) Slowly lower the temperature back to ambient with the bias voltage applied. Some pyroelectric detectors will spontaneously depole, albeit slowly, at room temperature. These detectors require periodic application of a poling bias, or even a constant bias, to maintain proper poling. 5.5.4.4 Applications of pyroelectric detectors
Perhaps the most pervasive use of pyroelectric detectors is in infrared motiondetection systems, in which two detectors are placed behind a Fresnel lens array to monitor a designated area. At the equilibrium, or no motion condition, there is no output signal from either detector. Motion of any thermally radiating object across the detectors’ fields of view causes a change in received power in one or both detectors, setting off an alarm or triggering the lighting of an area. A separate photocell within the system inhibits operation during daylight hours. Pyroelectric detectors are also employed in:
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163
(1) tympanic thermometers (2) laser power meters and beam profilers (3) thermal imaging systems (4) fire detection (5) pollution monitoring/gas analysis systems. Pyroelectric detectors are available as single elements and in one- and twodimensional arrays. Some two-element arrays are differential, with the elements wired in opposition. This scheme enhances sensitivity for motion detection systems. Other linear arrays are available with 128 and 256 elements. Twodimensional arrays have been made to 320 × 240 elements. 5.5.5 Other thermal detectors
The Golay cell was invented by M. J. E. Golay in 1947 for use in what was at that time the relatively new field of infrared spectrophotometry. It remains one of the most sensitive thermal detectors ever built. Figure 5.21 shows its construction. In operation, incoming radiation is absorbed by the blackened membrane which heats the gas within the cell and distends the membrane, which is silvered on the opposite side. Light from a lamp illuminates a Ronchi screen which is imaged on the membrane. The reflected beam passes through another Ronchi screen, and the photocell detects the modulation when the membrane moves. The Crooke radiometer is an early example of an optomechanical detector. It is pictured in Fig. 1.1 and consists of a rotating element with four flat vanes. Each vane is absorptive (black) on one side and reflective (polished) on the other. Theoretically, the rotation would be such that the reflective side would recede when radiant energy is incident. The momentum of the incident photons would be absorbed on the black side, and would recoil from the shiny side. This mode is never observed, as a very hard vacuum and virtually perfect bearing would be required. In practice, a small amount of residual gas is present inside the glass envelope, and the gas is heated by the black side of a vane. The local gas pressure is slightly higher at the black face than at the shiny face, resulting in a slight pressure differential. This causes the black face to recede from the incoming radiation.
Figure 5.21 Golay-cell-detector schematic.6 [Reprinted from Optical Radiation Measurement series, Vol. 4, W. Budde, Physical Detectors of Optical Radiation, p. 133 (1983).]
164
Chapter 5
Other optomechanical detectors include the liquid-in-glass thermometer, a bimetallic strip, and a piezoelectric bimorph.
5.6 Photon Detectors This section describes the most common photon detection schemes: the photoconductive, photoemissive, and photovoltaic. First, we need a brief review of some simple semiconductor physics. 5.6.1 Detector materials
Intrinsic semiconductors are nearly pure materials with a minimum concentration of impurities. Most have a well-defined energy gap. Photons with energies less than the energy gap value are not absorbed, but are either reflected or transmitted. For a photon to be absorbed, it must have a minimum energy and will then elevate an electron from the valence band (bound state) up into the conduction band (free state) such that it is available for conduction under an applied electric field. Figure 5.22 demonstrates this concept schematically, while Eq. (5.66) expresses the high wavelength cutoff beyond which electrons will not have the energy to reach the conduction band: λc =
hc 1.2398 , = Eg Eg
(5.66)
where λc = the high wavelength limit (cutoff wavelength) in micrometers, and Eg = the gap energy, or the minimum energy required to elevate an electron into the conduction band. It is expressed in electron volts (eV). Thermalization loss Conduction band
Ep = Photon energy
Eg = Gap energy
Ef = Fermi level
Valence band Figure 5.22 Illustration of valence and conduction bands, with Eg the energy necessary to promote an electron from the former to the latter.
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Another way to think about the concept is simply to recall that when Ep = hc/λ is greater than or equal to Eg, for a given material, electrons generated by photons at wavelength λ will possess the energy necessary to elevate into the conduction band. In Fig. 5.22, the excess energy Ep – Eg appears as heat. In the case of a photovoltaic cell (to be discussed in greater detail later) this thermalization loss causes the cell’s voltage and power to decrease. It is one of the two primary loss mechanisms responsible for the fairly low peak theoretical efficiency of about 28% for simple photovoltaic cells. A number of interesting intrinsic semiconductor materials are candidates for optical radiation detection, as shown in Table 5.11. For example, silicon is seen to require a maximum wavelength of 1.1 μm, 1100 nm, and this leads to the dramatic falloff on the right side of the photon detector curve seen in Fig. 5.1. Most of these materials may be categorized in a straightforward manner, but the last combination deserves special mention. Mercury telluride (HgTe) is classified as a semimetal, with a small negative energy gap. This means that HgTe is a conductor at room temperature, albeit a rather poor one. Cadmium telluride (CdTe) is a semiconductor which has been exploited for visible radiation detection. When the two tellurides are combined as Hg1–xCdxTe, then the energy gap depends on x, the fraction of CdTe in the mix. A mixture where x = 2 is common and yields a detector with response out to about 12 μm. The longest wavelengths that are practical with this trimetal detector are about 25 μm, and cold temperatures are required for effective operation. Table 5.11 Semiconductor materials useful for optical radiation detection.
Material SiC CdS CdSe GaP GaAs InP Si Ge PbS PbSe InAs InSb CdTe HgTe Hg1–xCdxTe HgCdTe (x = 2)
Energy gap (eV) 3.0 2.4 1.74 2.25 1.4 1.25 1.12 0.68 0.37 0.26 0.33 0.23 1.6 –0.3 variable 0.1
Cutoff λ (μm) 0.41 0.52 0.71 0.55 0.89 0.99 1.1 1.8 3.35 4.8 3.8 5.4 0.78 — 1 to 24 12.4
166
Chapter 5 Table 5.12 Intrinsic carrier concentrations for Si and InSb.
Material Si InSb InSb
T (K) 300 300 77
T3 2.7E7 2.7E7 4.6E5
Eg (eV) 1 23 23
e–Eg/kT 3.3–19 1.4–4 8.8–16
ni 1.3410 2.717 9.010
The relationship between intrinsic carrier concentration and temperature is due to thermal activity, and is expressed as: ni 2 = constant × T 3 × e
− Eg / kT
,
(5.67)
where ni = the concentration of carriers, constant ~ 2 × 1031 cm–6K–3 for most materials, and kT = 0.02585 at 300 K with units of eV.
Figure 5.23 shows the intrinsic carrier concentration plotted versus temperature, with energy gap as the parameter. As seen from the figure, an increase in temperature produces an increase in carrier concentration, and materials whose energy gap is large have lower carrier concentrations. Table 5.12 shows these effects for silicon and indium antimonide (InSb).
Figure 5.23 Intrinsic carrier concentration as a function of temperature for several Eg values.
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Looking at the two temperatures for InSb in Table 5.12, it is apparent that the T in the exponent in Eq. (5.67) has more influence on the calculated value of ni than does the T3 term. Since we want sufficient carriers available for photon excitation even at low values of ni, we must cool low Eg detectors that are designed for long-wavelength operation. This fact explains the need, for example, to cool HgCdTe detectors to temperatures of 77 K or lower. Detectors should be cooled so that kT
Io.
an op amp and feedback resistor. This mode is represented mathematically by setting V = 0 in Eq. (5.106). The result is that I = –Ig, in which current generated is a linear function of incident radiant power. This linearity is easily demonstrated to seven decades in radiometric quality silicon photodiodes, though unsubstantiated claims place the number of decades at 14. Open-circuit voltage is another operating condition for a photovoltaic detector. This is represented mathematically by setting I = 0 in Eq. (5.106) and solving for V: Voc =
β kT I o + I g ln q Io
.
(5.108)
If Ig >> Io, which is almost always the case, then Voc is logarithmic with radiant power as seen in Fig. 5.42. If Ig 1). The cutoff frequency is defined as the –3 dB (0.707) point, although there is substantial transmission for higher frequencies. The –3 dB point is at 1/τ rad/s or 1/(2πτ) Hz. The ENB of this simple filter is readily found by integrating the square (power transmission) of Eq. (F.3) in closed form; the result is π/(2τ) in rad/s, or 1/(4τ) = (π/2)fo expressed in Hz. The ENB is therefore π/2 or 1.571 times the –3-dB bandwidth, and everybody in Table F.1 agrees! For higher-order filters, the closed-form integration becomes more complex. It must be noted that whenever two or more RC sections are cascaded, the –3-dB point for the new composite filter shifts to lower frequencies; thus, one does not use the –3-dB point for a single RC section. In addition, multiple sections are buffered (isolated from each other) so that subsequent sections present no loading to preceding sections). The results of the higher-order integrations are shown in Table F.2. Table F.2 Low-pass Butterworth filter characteristics, matched sections.
Sections 1 2 3 4 5 6
ω–3 dB
(rad/s) 1/τ 0.644/τ 0.511/τ 0.436/τ 0.386/τ 0.350/τ
BSF
1.0 0.644 0.511 0.436 0.386 0.350
F–3 dB (Hz) 1/2πτ 0.102/τ 0.081/τ 0.069/τ 0.061/τ 0.056/τ
ENB (rad/s) π/2τ π/4τ 0.589/τ 0.492/τ 0.430/τ 0.387/τ
ENB (Hz) 1/4τ 1/8τ 0.094/τ 0.078/τ 0.068/τ 0.062/τ
Ratio ENB/B–3 dB π/2 = 1.571 1.220 1.155 1.130 1.115 1.106
300
Appendix F
These results confirm that the values given by Motchenbacher and Connelly and by Ott in Table F.1 are correct. Note that the third column represents a bandwidth shrinkage as sections are cascaded. This is also termed bandwidth shrinkage factor (BSF) when normalized to 1.0 for a single section. The formula for the effective (shrunk) bandwidth ratio of cascaded identical sections is BSF = 2(1/ n ) − 1 ,
(F.4)
where BSF is the net bandwidth ratio due to shrinkage by cascading sections. For design purposes, the bandwidth of the individual stages must be set to the reciprocal of the BSF. Bandpass filters with matched time constants
The simple RC bandpass filter with matched time constants cascades a single high-pass filter with a single low-pass filter, each with the same time constant τ = RC. The voltage transmission of a single-section RC high-pass filter is ωτ
A=
1 + ω 2 τ2
,
(F.5)
where ω is the radian frequency, equal to 2πf in Hz, and τ is the circuit time constant, the RC product, in seconds. At high frequencies, A approaches unity, and the curve falls at 6 dB/octave (20 dB/decade) at lower frequencies. The cutoff frequency is defined as the –3-dB (0.707) point, even though there is substantial transmission at lower frequencies. The –3-dB point, where ω2τ2 = 1, is 1/τ rad/s or 1/(2πτ) Hz. The peak transmission for these simple bandpass filters is no longer unity, and the –3-dB-bandwidth points must be evaluated with respect to the peak transmission of the composite filter, not unity. For the singlesection bandpass filter, a peak transmission of 0.5 (–6 dB) is found, located at the coincidence of the –3-dB points of the high-pass and low-pass sections. The –3-dB passband of the bandpass filter is determined at 3 dB below this level, or at –9 dB = 0.3535. The closed-form integration of this single-stage bandpass filter gives an ENB of πfC. Results for filters with one to four sections are shown in Table F.3. Note that the bandwidth shrinkage factor (BSF) matches the same ratios as for cascaded Butterworth low-pass filters. It should also be noted that the cut-on and cutoff frequencies are disposed about the center frequency in a geometric sense, i.e., fLP × fHP = fC2, where fC is the center frequency of the filter. The location of fLP is given by f LP =
fC 2
(
)
B2 + 4 − B ,
where B is either the –3-dB bandwidth or the ENB. fH is then fC2/fL.
(F.6)
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301
Table F.3 Butterworth bandpass filter characteristics with matched cascaded sections.
Sections Peak transmission B–3 dB/fC =1/Q BSF fLP/fC fHP/fC ENB/fC fLP/fC
1 0.5 2 1.0 0.414 2.414 π 0.291
2 0.25 1.287 0.644 0.546 1.833 π/2 0.486
3 0.125 1.019 0.511 0.613 1.632 1.177 0.572
4 0.0625 0.871 0.436 0.655 1.526 0.982 0.623
fHP/fC
3.432
2.057
1.749
1.605
ENB/B–3 dB
π/2
1.220
1.155
1.127
Bandpass Filters with Different Time Constants Here we discuss bandpass filters constructed using a single high-pass section in series with a single low-pass section. Each section has a different time constant. First we note that the minimum bandwidth is achieved with the low-pass cutoff and high-pass cut-on frequencies matched. If the low-pass cutoff is chosen at a lower frequency than the high-pass cut-on frequency, the resulting bandwidth remains the same as the case where the two frequencies are identical. The only thing achieved is a reduction in filter transmission. A simple BASIC program was written to find the ENB, the peak transmission, the –3-dB points, and the –3-dB bandwidth for these filters. Again the integrations were done for several selections of low-pass cutoffs and highpass cut-on frequencies, and the –3-dB points were located with respect to the composite transmission. The results are shown in Table F.4 for a single-section bandpass filter. These calculations were done holding fHP constant at unity. Table F.4 ENB for bandpass filters where fLP ≥ fHP.
fLP/fHP 1 1.5 2 3 4 5 6 10 20
Tpeak 0.5 0.6 0.667 0.75 0.8 0.833 0.857 0.909 0.952
B–3 dB 2 2.5 3 4 5 6 7 11 21
ENB 3.14 3.91 4.70 6.26 7.82 9.39 10.96 17.20 32.78
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Appendix F
From these data we find some surprisingly simple relationships. The maximum transmission is given by Tpeak =
f LP , f LP + f HP
(F.7)
and if fLP >> fHP, the peak transmission approaches unity as expected. The –3-dB bandwidth is given by
B−3 dB = f LP + f HP ,
(F.8)
so that if fLP >> fHP, the –3-dB bandwidth approaches that of the low-pass filter alone. The effective noise bandwidth is given by π ENB= B−3 dB . 2
(F.9)
Figure 7.63 in Horowitz and Hill shows a simple equation to relate the ENB for this case to the individual cut-on and cutoff frequencies: 2
f LP π . ENB = 2 f LP + f HP
(F.10)
If we were to use Eq. (F.10) to determine the ENB in the special case where fLP = fHP, it shows that the ENB is π/4 times the 3-dB bandwidth, which is less than the –3-dB bandwidth, a surprising result. This analysis shows that the ENB is (π/2) times the 3-dB bandwidth. It can be seen that when fL >> fH, the results of Eq. (F.10) converge to the correct solution, just that of the low-pass filter alone. A comparison between these new calculations for ENB and the results predicted using Eq. (F.10) is given in Table F.5. It is apparent that Eq. (F.10) gives erroneous results. Table F.5 Comparison with Horowitz and Hill.
fL/fH 1 2 5 10 20
ENB π 4.70 9.39 17.20 32.78
Eq. (F.10) π/4 2.09 6.55 14.28 29.9
Ratio 4 2.24 1.43 1.2 1.1
Effective Noise Bandwidth of Analog RC Filters…
303
Filter Selection to Optimize SNR We now address the selection of the optimum filter to maximize the signal-tonoise ratio. For many applications, we can ignore preservation of the signal waveform to achieve better SNR. We will recover just the fundamental with maximum SNR. Our discussion will be limited to “white” noise (uniform power spectral density). For the low-pass filter, the choice of cutoff frequency fC was determined using a short BASIC program to iterate fC for a fixed signal frequency of 100 (arbitrary units). The results show that for the single-section filter, the best SNR is obtained when fC is equal to the signal fundamental frequency. The results differ little for multisection low-pass filters. The double-section filter achieves its peak SNR at a frequency slightly higher (1.11 times the composite –3-dB point) than for the single-section filter. If we choose the composite –3-dB point, the SNR is 0.991 times the maximum achievable SNR. Three- and four-section filters showed similar results: the peak SNR was realized at about a 15% higher cutoff frequency, but the SNR at the composite –3-dB point was within 1% of the maximum SNR. Satisfactory results will be achieved by using the composite –3-dB frequency for one- to four-section low-pass filters. For the simple bandpass filter, where the high-pass and low-pass sections are set to the same frequency, the optimum SNR is achieved by setting both –3-dB points at the signal frequency, as that will maximize signal transmission. It was hypothesized that if the bandpass were increased somewhat, the transmission at the peak may increase faster than the noise, which is proportional to the square root of the ENB. To test this hypothesis, further spreadsheet work was done to implement the calculations. I again chose to keep the geometric mean of the lowpass and high-pass sections equal to the center frequency, i.e., fLP × fHP = fC2. The optimum SNR is achieved when the passband is defined where fL = fH. It can also be seen that setting the low-pass section to a lower frequency than the high-pass section is futile, yielding the same SNR, with both signal and noise attenuated equally. These above results are valid only for “white” noise. Every practical circuit has at a minimum a single RC time constant associated with it, defining an ENB and a corresponding SNR. If additional noise filtering is necessary, we can add a simple active filter using a single operational amplifier with two RC sections. It is then interesting to consider the simple bandpass filter (one section each matched high-pass and low-pass) and one- and two-section low-pass RC filters. The bandpass filter has an ENB of π and a peak gain of 0.5, whereas a single-section low-pass filter has an ENB of π/2 and a gain of unity. The noise transmission, the product of the peak transmission and ENB1/2, is 1.253 for the low-pass filter and 0.886 for the bandpass filter. The signal transmission for the low-pass filter is 0.707, whereas it is 0.5 for the bandpass filter. The SNR for each is therefore the same. However, for a twosection low-pass filter with the signal at the (composite) –3-dB frequency, the ENB is 1.220 × fC, the noise transmission is 1.105, the signal transmission is
304
Appendix F
0.707, and the SNR is therefore improved by some 13.5% over the simple bandbass and single-section filters.
Conclusions Several recommendations can be made: (1) A double-section (second-order) low-pass filter is sufficiently better in the reduction of white noise to warrant the use of two additional components. (2) In the absence of 1/f noise, a two-section low-pass filter will outperform a bandpass filter with the same number of components. (3) When cascading (identical) sections of Butterworth-type filters, the BSF must be taken into account. (4) When noise content of the (linear) signal channel is other than white noise, additional noise suppression techniques may be needed. Transient suppression and 1/f noise effects are not covered in this discussion. In the case of system nonlinearities (such as pulsed signals or in certain laser applications), judicious addition of certain types of noise can actually improve the SNR. This is called stochastic resonance, and it is beyond the scope of this book. (5) The above discussion relates only to the linear-circuit analog domain. Once the filtered signal becomes digitized, quantization noise and antialiasing effects must be taken into account. A good rule of thumb to follow is that use of a first-order filter requires a sample rate of at least five times the cutoff frequency of the filter. Only then will the filter fully meet the Nyquist criteria (to minimize aliasing in the digital output of the A/D converter).
Appendix G
Bandwidth Normalization by Moments General measurement equation: ∞
I = ℜ ( λ ) Φλ d λ . 0
(G.1)
If ℜ(λ) can be represented as a rectangle, λ2
I = ℜn Φ λ d λ . λ1
(G.2)
Let the source function Φλ be described as a second-degree polynomial: Φλ = A + Bλ + Cλ2.
(G.3)
Substitute Eq. (G.3) into Eq. (G.1), divide both sides by ℜ(λ)dλ, and multiply both sides by (λ2 – λ1) to get: ∞ ∞ λℜ ( λ ) d λ λ 2ℜ ( λ ) d λ 0 0 (λ − λ ) . = A+ B ∞ +C ∞ 1 ∞ 2 ℜ λ λ ℜ λ λ ℜ λ λ d d d ( ) ( ) ( ) 0 0 0
I (λ 2 − λ1 )
(G.4)
Next, integrate Eq. (G.3) between the limits λ1 and λ2:
λ2
λ1
B C Φ λ d λ = A + ( λ 2 + λ1 ) + ( λ 22 + λ 2 λ1 + λ12 ) ( λ 2 − λ1 ) . 2 3
(G.5)
Note the similarities between Eqs. (G.4) and (G.5). If the following conditions are applied,
305
306
Appendix G ∞
λℜ ( λ ) d λ , ℜ(λ ) dλ
λ 2 + λ1 = 2
0
∞
λ 22 + λ 2 λ1 + λ12 = 3
0
and
λ2
λ1
Φλ d λ =
I ( λ 2 − λ1 )
∞
0
ℜ(λ) dλ
∞
0
λ 2ℜ ( λ d λ ) ∞
0
ℜ(λ dλ)
.
(G.6)
(G.7)
Assume that area of response curve = area of equivalent rectangle, i.e. ∞
ℜn ⋅ Δλ = ℜ ( λ ) d λ .
(G.8)
0
Then,
λ2
λ1
Φλ d λ =
I , ℜn
(G.9)
and we have a band-limited power Φin-band. Now we proceed to determine λ1, λ2, and ℜn. Substitute: ∞
M1
λℜ ( λ ) d λ = ℜ(λ) dλ 0
∞
M2
=
∞
0
λ 2ℜ ( λ ) d λ ∞
0
0
ℜ(λ) dλ
.
(G.10)
Then M1 =
λ 2 + λ1 2
M2 =
λ 22 + λ 2 λ1 + λ12 . 3
(G.11)
M1 is the first moment divided by the area (0th moment) and is the centroid of the response curve, the effective or center wavelength λc. M2 is the second moment divided by the area, which is related to the square of the radius of gyration. Solution of simultaneous Eqs. (G.11) with the substitution M1 = λc yields λ1 = λ c − 3(M 2 − λ c 2 ) , λ 2 = λ c + 3(M 2 − λ c 2 ) ,
(G.12)
showing the bandpass limits λ1 and λ2 are symmetrically disposed about the center wavelength λc. The quantity (M2 – λc2) is recognized as the variance σ2. The bandwidth between wavelength limits λ1 and λ2 is:
Δλ = λ 2 − λ1 = 2 3 σ , and the short- and long-limit wavelengths are then
(G.13)
Bandwidth Normalization by Moments
307
λ1 = λ c − 3 σ λ 2 = λ c + 3 σ .
(G.14)
The bandwidth-normalized responsivity is
ℜn =
1 2
∞
ℜ(λ) dλ . 3σ
(G.15)
0
Now we have our three parameters, ℜn, λ1, and λ2. Note that the coefficients A, B, and C of the second-degree source polynomial [Eq. (G.3)] have vanished. The implication is significant: • Any source that can be represented by a second-degree polynomial can be characterized between the wavelength limits λ1 and λ2 (which are determined solely by the radiometer) without error. • There is no ambiguity in any of the normalization parameters; they are all uniquely determined from only the spectral responsivity curve. • The errors are related to the deviation of the source function from a quadratic.
Moments Normalization Summary This is the step-by-step procedure for accomplishing a moments normalization. The starting point is absolute spectral responsivity ℜ(λ). ∞
Zero’th moment
M 0 = ℜ(λ) dλ
First moment
M1 = λ ℜ ( λ ) d λ
Second moment
M 2 = λ2 ℜ ( λ ) d λ
Center wavelength (centroid) Variance
0
∞
0
∞
0
M1 M0 M σ2 = 2 − λ c2 M0 λc =
Short wavelength limit
λ1 = λ c − 3σ
Long wavelength limit
λ 2 = λ c + 3σ
Bandwidth
Δλ = 2 3σ M0 ℜn = 2 3σ
Normalized responsivity
Appendix H
Jones Near-Small-Source Calibration Configuration The following method is adapted from an obscure application note further describing the near-small-source method of radiometric calibration.
How to calibrate a radiometer A simple method of calibrating a radiometer using a small blackbody source close to the radiometer aperture has been described by Dr. R. Clark Jones of the Polaroid Corporation. The principles involved in this method are briefly reviewed here with special emphasis on the application to the optithermradiometer Cassegrain system. The essential point in the method is that a small radiation source close to the aperture of the radiometer will uniformly irradiate an area in the focal plane of the radiometer. The radiation on the detector (with the radiometer focused at infinity) is then given by
Φ = Ls Ad ωr ,
(H.1)
where Φ = radiation on detector (watts, Φ) L = source radiance (W/m2sr, Ls) Ad = detector area (m2) ωr = solid angle of radiometer field of view (sr) at the focal plane = source area / (focal length)2. Thus, the responsivity of a detector in a radiometer can readily be calibrated by dividing the signal voltage output of the instrument by the radiation on the detector. An important aspect of the method is that the radiation on the detector is independent of the radiometer aperture and source location, providing that a uniformly irradiated area covers the detector. This restriction places limits on the source size and location as given below.
309
310
Appendix H
Focal plane Image, I
Dpi (Entrance pupil of radiometer)
Df
Point source, S
f
P
Q Figure H.1 Point source near a radiometer. The detector surface is located at the focal plane.
Consider a point source near a radiometer (Fig. H.1). For a point source, the diameter of the uniformly irradiated disc Df in the focal plane is given by Eq. (H.2) (after using the thin-lens imaging formula):
Df =
f D pi , P
(H.2a)
where Df, f, P, and Dpi are defined in Fig. H.1. The size of the detector must be less than Df. It is easy to prove Eq. (H.1) for the configuration shown in Fig. H.1. For a small Lambertian source, flux at the entrance pupil of the radiometer is given by Φ D pi = Ls As AD pi / P 2 .
(H.3)
For a detector of size Df at the focal plane of the radiometer, the flux detected is given by
Φ D f = Ls AD f ωr .
(H.4)
But we know that Φ D pi = Φ D f . So, from Eqs. (H.2), (H.3), and (H.4), we get
ωr = As/f 2.
(H.5)
Asssuming uniform irradiance at the focal plane, Eq. (H.4) can be written as Eq. (H.1).
Jones Near-Small-Source Calibration Configuration
311
Similarly, if the radiometer optical system is of the Cassegrain type, an obscured area will result, and the uniformly irradiated area will then be an annular ring of width χ and mean diameter Dm:
χ=
1 f ( DP1 − DP 2 ) , 2P
(H.6a)
where DP2 = the diameter of an obscured disc produced by secondary mirror.
Dm =
1 f ( DP1 + DP 2 ) . 2P
(H.7)
If, as is always the case, the source has a finite diameter Ms (see Fig. H.2), the edges of the disc or ring will be vignetted by an amount (f Ms/P), divided equally on either side of the unblurred edge. The remaining uniformly irradiated disc or annular ring width is given by f ( DP1 − M S ) , P
(H.2b)
f 1 ( DP1 − DP 2 ) − M S . P 2
(H.6b)
Dx =
χ=
The mean diameter of the ring remains the same as given in Eq. (H.7).
Figure H.2 Thin-lens-equivalent layout for a Cassegranian optical system.
312
Appendix H
In calibrating a radiometer, a convenient source aperture and distance are first chosen. Then the size of the uniformly irradiated area must be checked to see whether it covers the detector. For example, if a Cassegrain system is used, the detector must fit in the ring of width z and mean diameter D as computed from Eqs. (H.6b) and (H.7). The source must be placed off axis such that the annular ring of width x falls on the detector. Several other precautions must be observed, particularly if a thermal detector is used. Since the calibration source fills only a small part of the field of view, the detector will “see” other radiation as well. If the source is chopped, the radiometer will respond only to it. However, in many cases the detector is chopped, and hence it responds to all radiation in its field of view. One way of separating the response to the calibration source from the background is to record the difference in response when the source aperture is opened and when it is closed.
Appendix I
Is Sunglint Observable in the Thermal Infrared? The short answer is yes. Orbiting spacecraft like GOES, AVHRR, ASTER, MODIS, and ATSR all have spectral observation windows in the thermal infrared. They all have to deal with sunglint at least some of the time. It is not just a minor nuisance, but a major effect that saturates their sensors. A saturated sensor gives no indication of the actual magnitude; all information from that direction is lost. The directional characteristics of sunglint have been adequately treated by Maurice Cox.1 This report deals with the radiometric aspects, the magnitude of the sunglint in comparison with the magnitude of normal target thermal emission.
Background Every object at a temperature above absolute zero emits electromagnetic radiation (EMR) as a result of molecular motion. This emission as a function of wavelength is described by the Planck equation 2hc 2 1 Lλ = ε ( λ ) 5 hc / λkT , −1 λ e
(I.1)
where Lλ is spectral radiance in W/m2sr, ε(λ) is spectral emissivity, a wavelengthdependent quality factor, h is Planck’s constant, c is the velocity of light, λ is wavelength, k is Boltzmann’s constant, and T is the absolute temperature. This equation gives the spectral radiance in W/m2sr·μm at any wavelength for an object at temperature T. If ε(λ) is 1 at all wavelengths, the emission is called blackbody radiation. For temperatures on the order of room temperature (~300 K, 80° F) this radiation peaks near 10 μm, and the region surrounding 10 μm is known as the thermal infrared (TIR). When a beam of EMR encounters an object, three things can happen. The object can: 1. absorb the EMR, 2. transmit the EMR, or 3. reflect the EMR. 313
314
Appendix I
In fact, all three processes happen simultaneously: an object reflects some of the incoming EMR, absorbs some of it, and transmits the balance. All of these three are relative quantities, the fraction reflected, absorbed, or transmitted, and have values between 0 and 1. Since EMR must be conserved, the sum of these three is 1:
A + T + R = 1.
(I.2)
This means that if an object is highly reflective (R→1, like a mirror), the sum of the absorption and transmission must necessarily be low. Similarly, if the object is transparent (T→1, like a window), it must have both low absorption and low reflection. Kirchhoff related the absorption and emission of an object, stating that if an object is a good absorber, it must also be a good emitter. With Kirchhoff’s law in mind, objects that are highly reflective or highly transmissive cannot be good emitters. The TIR is an interesting place to observe things. An infrared camera or forward-looking infrared (FLIR) “sees” a picture of the distribution of radiance in the observed scene, which usually includes an object of interest, a target. The observed radiance is comprised of three factors, the direct emission from the target, the radiance of whatever is behind the target multiplied by the transmittance of the target, and the radiance of whatever surrounds the target multiplied by the reflectance of the target. These cameras do not observe at all wavelengths, but are limited by the transmission of their optics and that of our atmosphere. Two “windows” are commonly used, between 3 and 5 μm and between 8 and 12 μm. In general, the 3- to 5-μm window is better suited for hotter targets and the 8- to 12-μm window is best for objects near room temperature. To determine the radiance within the wavelength region defined by an atmospheric window, we integrate Eq. (I.1) over the TIR wavelength range. The integration can be done with standard mathematical computer programs (i.e., MathCad, Mathematica, etc.), a custom computer program, or even brute force using a spreadsheet. Another issue with which we must deal is the atmosphere itself. It has a transmission less than one, and it also radiates in the thermal infrared according to Eq. (I.1). The problem is extraordinarily complex, and massive computer programs have been devised to determine the characteristics of our atmosphere. For this work, the program PCTRAN (www.ontar.com), a commercial version of the USAF program LOWTRAN7, has been used to determine the relevant parameters. To keep the analysis quite general, the preprogrammed atmosphere known as MID-LATITUDE SUMMER was chosen as characteristic of a broad range of characteristics in the CONUS over at least half of the year. The altitude was taken at sea level, and the solar zenith angle (as measured from directly overhead) was 25 deg. At this angle, the calculated transmission, averaged over the TIR (8- to 12-μm band), is 0.57, and the in-band radiance of the sky in this direction is 12.5 W/m2sr. The radiance was also determined over a range of
Is Sunglint Observable in the Thermal Infrared?
315
angles and integrated to determine the total in-band irradiance on the ground from the entire sky; it is 51.2 W/m2.
Direct Emission Most objects seen by FLIR devices are at ambient temperature, here taken as 300 K (80° F). A 300-K blackbody has an in-band (8- to 12-μm) radiance of 38.5 W/m2sr. For real objects, we multiply by the emissivity; for this analysis the emissivity is assumed to be constant over the band. We consider four materials: earth, water, aluminum, and glass. Table I.1 gives the radiative characteristics. The difference between the aluminum and the other materials is that aluminum is a good reflector and therefore a poor emitter. This is a characteristic of metals, which are good electrical conductors.
Reflected Radiation If these materials have an emissivity less than unity, the sum of their reflectance and transmittance must make up the difference. Since all of these materials are opaque (T = 0) in the TIR, the reflectance is (1 – emissivity). The directional properties of reflectance are highly varied, from perfectly diffuse (flat, matte) to perfectly specular (like a perfect mirror). We shall inspect the two limiting cases. Since the materials are reflecting something we must determine what that something is. For an object out-of-doors, lying horizontally on the ground, the background consists of three parts: the sun, the sky, and nearby objects that are above grade. Because of the variability of above-grade objects, we shall ignore them, assuming our object of interest is out in the open. The radiance of the sky, obtained via PCTRAN, was previously stated to be 12.5 W/m2sr at 25-deg zenith angle. The sun is assumed to be a blackbody at 6000 K and subtends a solid angle of 6.8 × 10–5 sr. The in-band radiance from a 6000 K blackbody is 19840 W/m2sr, so the irradiance outside the atmosphere is the product of the radiance and the solid angle and is 1.35 W/m2. After transmission through the atmosphere, the irradiance is reduced to 0.77 W/m2, a rather feeble amount.
Table I.1 Direct TIR emission from selected materials (300 K).
Material
Earth Water Aluminum Glass
Emissivity (8- to 12-μm band) 0.95 0.985 0.1 0/96
Radiance W/m2sr 36.6 37.9 3.85 37.0
316
Appendix I Table I.2 Reflected radiance from diffuse materials.
Material Earth Water Aluminum Glass
Diffuse reflectance 0.05 0.015 0.9 0.04
Reflected sun (W/m2sr) 0.012 0.004 0.22 0.010
Reflected sky (W/m2sr) 0.81 0.24 14.67 0.65
Diffuse reflectance
For diffuse objects, we invoke the Lambertian approximation, which states that radiance is independent of direction and is the product of the irradiance and the reflectance, divided by π, or ρ L= E. (I.3) π This equation may be used directly for a source like the sun. For a uniform hemispherical diffuse source like the sky, the irradiance E is π times the source radiance, so the reflected radiance is simply the source radiance multiplied by the surface reflectance. The sky is not really uniform, but for a diffuse reflector, we can use the total irradiance from the sky, multiply by the reflectance, and divide by π. Table I.2 shows the reflected radiance of each of these four materials from the direct sunlight and from the sky. Sunlight reflected from a diffuse surface in the 8- to 12-μm band is very small. The total radiance from all of these objects is the sum of the direct and reflected components, as shown in Table I.3. Note that with the exception of the aluminum, they are comparable, and will look much the same on a thermal image. The aluminum, being reflective rather than emissive, has a significantly lower radiance, and will appear dark on a typical FLIR display (“white-hot,” where a more radiant object appears white and a less radiant object appears black). Since we do not know a priori the nature of the objects in the scene, dark objects will be interpreted as cooler than white objects. Specular reflectance
Reflection from smooth surfaces is called specular, and straightforward laws of geometry apply. The incident and reflected beams and the normal to the reflecting surface all lie in the same plane, and the angles of both the incident and reflected beams with respect to the normal to the reflecting surface are equal. For an outdoor scene viewed from above, this means that at one specific angle, which must follow the above rules, the sun will be seen. At all other angles, the sky will be seen.
Is Sunglint Observable in the Thermal Infrared?
317
Table I.3 Total radiance from diffuse materials.
Material
Earth Water Aluminum Glass
Direct radiance (W/m2sr) 36.6 37.9 3.85 37.0
Reflected sun (W/m2sr) 0.012 0.004 0.22 0.010
Reflected sky (W/m2sr) 0.81 0.24 14.67 0.65
Total radiance (W/m2sr) 37.42 38.14 18.74 37.66
Window method
One way to look at the problem is to treat the reflecting surface as a window through which the sun or the sky can be viewed. This window has the same size and orientation as the reflecting surface, and its transmission has the same value as the reflection of the reflecting surface. In this model, the effective radiance is the product of the surface reflectance and the radiance of whatever is seen in reflection. Table I.4 gives the effective radiance of the three materials that are capable of specular reflectance for both sunlight and skylight. Recall that the radiance of the sky in the 8- to 12-μm band (zenith angle 20 deg) is 12.5 W/m2sr, and the transmittance of the atmosphere is 0.57. The in-band radiance of the sun (before atmospheric losses) is 19840 W/m2sr, so the effective radiance, including the atmospheric transmission, is 11310 W/m2sr. The radiance of the object from a uniform diffuse sky is seen to be the same whether the reflector is diffuse or specular. When compared with the typical total radiances for diffuse surfaces, it can be seen that the specularly reflected sun (sunglint) is a factor of 5 to nearly 300 times the total from a diffuse surface (~37.5 W/m2sr). BRDF method
Another way of looking at reflection is through the concept of bidirectional reflectance distribution function (BRDF). This term is the ratio of the radiance of a surface, as a function of direction, to the irradiance incident upon the surface. It carries the units 1/sr. The BRDF is the surface reflectance divided by the projected solid angle of the irradiating source. The radiance of a surface is then the product of the irradiance E and the BRDF, or L = E × BRDF. For a diffuse Table I.4 Reflected radiance from specular materials.
Water
Specular reflectance 0.015
Reflected sun (W/m2sr) 170
Reflected sky (W/m2sr) 0.19
Aluminum
0.9
10180
11.25
Glass
0.04
452
0.50
Material
318
Appendix I Table I.5 Reflected radiance from specular materials via BRDF.
Water
Specular reflectance 0.015
BRDF from sun 221
Irradiance from sun (W/m2) 0.77
Reflected sun (W/m2sr) 170
Aluminum
0.9
13235
0.77
10190
Glass
0.04
588
0.77
453
Material
surface, the BRDF is ρ/π and the radiance L is then ρE/π. For a hemispherical diffuse source like the sky, the irradiance E is the source radiance Lsky multiplied by the projected solid angle of the source, which is π. Then the object radiance is just the source radiance Lsky times the reflectance ρ. For a specular surface, the BRDF is the surface reflectance divided by the projected solid angle of the source, or ρ/Ω. The sun has a projected solid angle of 6.8 × 10–5 sr, so the BRDF becomes 14706 ρ. Using these values, Table I.5 gives the reflected radiances. The feeble 0.77 W/m2 irradiance from the sun turns into an overwhelming radiance upon specular reflection. The results of the BRDF computation of the glint radiance are identical to the results obtained using the “window” method. Several factors can alter these results. First, the surface must be flat and clean. The presence of a scattering overlay, like a layer of dust, will remove a portion of the specularity and add a diffuse component. Second, the polish on the surface must be fairly good, though at these longer wavelengths, the surface roughness can be over ten times as great as that of a mirror designed for reflection in the visible. The effect of this large radiance on a FLIR depends upon several factors. First, our sensor must be positioned such that it is (1) located within the specular beam, and (2) looking in the proper direction. The instantaneous field of view (IFOV) of the sensor is the angle that a single detector subtends when observing a target and is measured in milliradians (mrad). Detector considerations (number and diffraction-limited size) and overall instrument constraints (aperture size, focal length, and these combined as f/#) place typical values of IFOV in the neighborhood of 0.1 to 0.2 mrad. If the detector is square, the footprint, or target area seen by the detector, is also nearly square, depending upon the viewing angle. The observed area of the target is then (IFOV × R)2 where R is the range, the distance from the target to the sensor. For example if the range is 1 km (3280 ft), the area seen by a detector with an IFOV of 0.1 mrad is 0.01 m2, and the detector footprint is a square 0.1 m (about 4 in.) on a side. Larger IFOV and/or larger range will cause an increase in the size of the detector footprint. If we are looking at an angle from nadir (which is vertical, straight down) then we divide the footprint by the cosine of the angle from nadir. The increase is small for low values of nadir angle; a 10% increase in effective area is seen if the nadir angle is 25 deg.
Is Sunglint Observable in the Thermal Infrared?
319
The power on a detector from glint depends upon the size of the reflecting object compared with the detector footprint. The diameter of the sun subtends nearly 9 mrad, sufficiently large to overfill any properly oriented detector. The total radiance as seen by a detector is the sum of the earth radiance and the glint radiance, each weighted by its fraction of the subtended area. For example, a single square piece of glass (ρ = 0.04) that is 1 cm on a side has an area of 10–4 m2. If the detector footprint is 10–2 m2, the fraction subtended by the glass is 0.01 (1%). The remaining earth has a fractional area of 0.99 (99%). Taking the radiances from above and weighting them according to these fractional areas, we get 0.01 × 450 + 0.99 × 36.6 = 40.7 W/m2sr. Specular reflection of sunlight from a small piece of glass results in an 11% increase in radiance over the bare earth at 300 K (26.8° C, 80° F). This increase in radiance would be interpreted as a temperature difference of 12° F, a rise from 80° F to 92° F. An IFOV that includes the same size piece of shiny aluminum (square, 1 cm on a side) will have a total radiance of 0.01 × 10200 + 0.99 × 36.6 = 138.2 W/m2sr. This radiance is likely to saturate a detector. If a detector does have sufficient dynamic range to respond linearly to this radiance, it will indicate a temperature of 409 K (136° C, 276° F), which is totally unrealistic.
Conclusion We have demonstrated here that sunglint can be a significant factor in imaging systems in the thermal infrared. It will be observed if the sensor is looking at a target with a sunglint component, and the geometrical angles are such that the sun can be seen in reflection. The only way to avoid it is to look in some other direction.
Works Consulted 1. M. Cox, Sun Reflection Geometry, (1999). Unpublished. 2. A. W. Cooper, E. C. Crittenden, E. A. Milne, P. L. Walker, E. Moss, and D. J. Gregoris, “Mid- and far-infrared measurements of sunglint from the sea surface,” in Proc. SPIE 1749, 176–185 (1992). The first five authors are from the Naval Postgraduate School, Monterey, CA. Measurements were made with an AGA Thermovision 780 dual-band camera operating in the 2- to 5.6-μm and 8- to 12-μm bands.
Appendix J
Documentary Standards for Radiometry and Photometry Numerous agencies prepare and disseminate documentary (protocol) standards for radiometry and allied fields. Those listed here are either U.S. or international standards organizations. The European Committee for Standardization is called CEN,i whose mission is to promote voluntary technical harmonization in Europe in conjunction with worldwide agencies and its European partners. The purposes include the lowering of trade barriers and the promotion of common technical understanding. European standards (e.g., BSI from UK and DIN from Germany) may be accessed via CEN. The Japanese Standards Associationii also has extensive listings.
ANSI American National Standards Institute. The U.S. representative for ISO, the International Standards Organization. iii C78.40-1985 C78.180-1989 C78.375-1991 C78.386 C78.387 C78.388 C82.1-1985 C82.1(a-c) 1990 C82.3-1989 C82.4-1985
i
Specifications for mercury lamps Specifications for fluorescent lamp starters Guide for electrical measurements of fluorescent lamps Mercury lamps—measurement of characteristics Metal-halide lamps—measurement of characteristics High-pressure sodium lamps—measurement of characteristics Specifications for fluorescent lamp ballasts Specifications for fluorescent lamp ballasts (supplement to C82.1) Specifications for fluorescent lamp reference ballasts Specifications for intensity discharge and low-pressure sodium amp ballasts
www.cenorm.be/ www.jsa.or.jp iii (www.ansi.org) ANSI/IES RP-16, American National Standard Nomenclature and Definitions for Illuminating Engineering (1986). 321 ii
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C82.5-1990 C82.6-1985 ANSI/NCSL 540-1-1994
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Specifications for high-intensity-discharge lamp reference ballasts Methods of measurement of discharge lamp ballasts American National Standards for Calibration—calibration Laboratories and Measuring and Test Equipment—general requirements
ASTM The American Society for Testing and Materialsiv maintains an extensive collection of protocol or documentary standards, including practices, specifications, guides, procedures, and test methods for a large range of materials and instrumentation for their characterization. Some 10,000 standards are published annually in a 73-volume set, of which one volume is the index alone! The ASTM Book of Standards occupies nearly two meters of shelf space. These documents are subject to periodic review and revision by the committees that were responsible for their generation and maintenance. Always check at ASTM’s website to see if a later version is available. A number of these standards are the result of the efforts of committee E12 on Color and Appearance, committee E20 on Temperature Measurement and committee E37 on Thermal Measurement. Special collections in specific areas are also published, for example, ASTM Standards on Color and Appearance Measurement, 8th Ed. (2008). This book contains 130 ASTM standards as well as ISO and ISO/CIE standards used in appearance analysis for a variety of materials and products, including all the standards listed above. It includes a CD/ROM with even more information. The following listing shows a selection of relevant standards to radiometry, photometry, and colorimetry. Another useful guide is “Nomenclature and Definitions Applicable to Radiometric and Photometric Characteristics of Matter,” ASTM Special Technical Publication 475 (1971). “Guide for recommended uses of photoluminescent safety markings,” ASTM E2030 (1999). “Standard practice for preparation of pressed powder white reflectance factor transfer standards for hemispherical geometry and bi-directional geometries,” ASTM E259 (1998). “Recommended practice for goniophotometry of objects and materials,” ASTM E167 (1996). “Specification for daytime pedestrian visibility enhancement,” ASTM E1896 (1997). “Standard guide for describing and specifying the spectrometer of an optical emission direct-reading instrument,” ASTM E1507 (1998) .
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“Standard guide for designing and conducting visual experiments,” ASTM E1808 (1996). “Standard guide for establishing spectrophotometer performance tests,” ASTM E1866 (1997). “Standard guide to evaluation of optical properties of powder coatings,” ASTM D5382 (1995). “Standard guide for examining electrical and mechanical equipment with infrared thermography,” ASTM E1934 (1999). “Standard guide for modeling the colorimetric properties of a visual display unit,” ASTM E1682 (2001). “Standard guide for preparation, maintenance, and distribution of physical product standards for color and geometric appearance of coatings,” ASTM D5531 (1999). “Standard guide for quality assurance of laboratories using molecular spectroscopy,” ASTM E924 (1994). “Standard guide for quantitative analysis by energy-dispersive spectroscopy,” ASTM E1508 (1998). “Standard guide for Raman shift,” ASTM E1840 (1996). “Standard guide for selection of geometric conditions for measurement of reflection and transmission properties of materials,” ASTM E179 (1996). “Standard guide for use of lighting in laboratory testing,” ASTM E1733 (1995). “Standard guide to evaluation of optical properties of powder coatings,” ASTM D5382 (1995). “Standard guide to properties of high visibility materials used to improve individual safety,” ASTM F923 (2000). “Standard method for calibration of reference pyranometers with axis vertical by the shading method,” ASTM E913 (1999). “Standard practice for angle resolved optical scatter measurements on specular or diffuse surfaces,” ASTM E1392 (1996). “Standard practice for calculating solar reflectance index of horizontal and lowsloped opaque surfaces,” ASTM E1980 (2001). “Standard practice for calculating yellowness and whiteness indices from instrumentally measured color coordinates,” ASTM E313 (2000). “Standard practice for calculation of photometric transmittance and reflectance of materials to solar radiation,” ASTM E971 (1996). “Standard practice for calculation of weighting factors for tristimulus integration,” ASTM E2022 (2001). “Standard practice for calibrating thin heat flux transducers,” ASTM C1130 (2001).
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“Standard practice for calibration of ozone monitors and certification of ozone transfer standards using ultraviolet photometry,” ASTM D5110 (1998). “Standard practice for calibration of the heat flow meter apparatus,” ASTM C1132 (1995). “Standard practice for calibration of transmission densitometers,” ASTM E1079 (2000). “Standard practice for calculating yellowness and whiteness indices from instrumentally measured color coordinates,” ASTM E313 (2000). “Standard practice for color measurement of fluorescent specimens,” ASTM E991 (1998). “Standard practice for computing the colors of fluorescent objects from bispectral photometric data,” ASTM E2152 (2001). “Standard practice for computing the colors of objects by using the cie system,” ASTM E308 (1999). “Standard practice for describing and measuring performance of dispersive infrared spectrometers,” ASTM E932 (1997). “Standard practice for describing and measuring performance of fourier transform mid-infrared (FT-MIR) spectrometers level zero and level one tests,” ASTM E1421 (1999). “Standard practice for describing and measuring performance of laboratory fourier transform near-infrared (FT-NIR) spectrometers: level zero and level one tests,” ASTM E1944 (1998). “Standard practice for describing and measuring performance of ultraviolet, visible, and near-infrared spectrophotometers,” ASTM E275 (2001). “Standard practice for describing and specifying inductively-coupled plasma atomic emission spectrometers,” ASTM E1479 (1999). “Standard practice for describing photomultiplier detectors in emission and absorption spectrometry,” ASTM E520 (1998). “Standard practice for describing retroreflection,” ASTM E808 (1999). “Standard practice for determining the steady state thermal transmittance of fenestration systems,” ASTM E1423 (1999). “Standard practice for electronic interchange of color and appearance data,” ASTM E1708 (2001). “Standard practice for establishing color and gloss tolerances,” ASTM D3134 (1997). “Standard practice for evaluating solar absorptive materials for thermal applications,” ASTM E744 (1996). “Standard practices for general techniques of ultraviolet-visible quantitative analysis,” ASTM E169 (1999). “Standard practice for goniophotometry of objects and materials,” ASTM E167 (1996).
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“Standard practice for identification of instrumental methods of color or colordifference measurement of materials,” ASTM E805 (2001). “Standard practice for measuring colorimetric characteristics of retroreflectors under nighttime conditions,” ASTM E811 (2001). “Standard practice for measuring photometric characteristics of retroreflectors,” ASTM E809 (2000). “Standard practice for measuring practical spectral bandwidth of ultravioletvisible spectrophotometers,” ASTM E958 (1999). “Standard practice for near infrared qualitative analysis,” ASTM E1790 (2000). “Standard practice for obtaining bispectral photometric data for evaluation of fluorescent color,” ASTM E2153 (2001). “Standard practice for obtaining colorimetric data from a visual display unit using tristimulus colorimeters,” ASTM E1455 (1997). “Standard practice for obtaining spectrophotometric data for object-color evaluation,” ASTM E1164 (1994). “Standard practice for obtaining spectroradiometric data from radiant sources for colorimetry,” ASTM E1341 (2001). “Standard practice for preparation of pressed powder white reflectance factor transfer standards for hemispherical geometry and bi-directional geometries,” ASTM E259 (1998). “Standard practice for preparation of textiles prior to ultraviolet (uv) transmission testing,” ASTM D6544 (2000). “Standard practice for qualifying spectrometers and spectrophotometers for use in multivariate analyses, calibrated using surrogate mixtures,” ASTM E2056 (2000). “Standard practice for reducing the effect of variability of color measurement by use of multiple measurements,” ASTM E1345 (1998). “Standard practice for selecting and calibrating sources for the visual assessment of object colors,” ASTM Z6606Z. “Standard practice for selection and use of portable retroreflectomers for the measurement of pavement marking materials,” ASTM E1743 (1996). “Standard practice for solar simulation for thermal balance testing of spacecraft,” ASTM E491 (1999). “Standard practice for specifying and matching color using the colorcurve system,” ASTM E1541 (1998). “Standard practice for specifying and verifying the performance of colorimeters, spectrocolorimeters and goniospectrocolorimeters,” ASTM Z6899Z. “Standard practice for specifying color by the munsell system,” ASTM D1535 (2001). “Standard practice for specifying color by using the optical society of america uniform color scales system,” ASTM E1360 (2000).
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“Standard practice for specifying the geometry of observations and measurements to characterize the appearance of materials,” ASTM E1767 (1995). “Standard practice for the periodic calibration of narrow band-pass spectrophotometers,” ASTM E925 (1994). “Standard practice for testing fixed-wavelength photometric detectors used in liquid chromatography,” ASTM E685 (2000). “Standard practice for testing variable-wavelength photometric detectors used in liquid chromatography,” ASTM E1657 (2001). “Standard practice for transfer standards for reflectance factor for near-infrared instruments using hemispherical geometry,” ASTM E1791 (2000). “Standard practice for validation of multivariate process infrared spectrophotometers,” ASTM D6122 (1999). “Standard practice for visual appraisal of colors and color differences of diffusely-illuminated opaque materials,” ASTM D1729 (1996). “Standard practice for visual color evaluation of transparent sheet materials,” ASTM E1478 (1997). “Standard practice for visual evaluation of metamerism,” ASTM D4086 (1997). “Standard practices for general techniques of ultraviolet-visible quantitative analysis,” ASTM E169 (1999). “Standard practices for infrared multivariate quantitative analysis,” ASTM E1655 (2000). “Standard Practices for Internal Reflection Spectroscopy,” ASTM E573 (2001) “Standard Solar Constant and Zero Air Mass Solar Spectral Irradiance Tables,” ASTM E490 (2000). “Standard specification for infrared thermometers for intermittent determination of patient temperature,” ASTM E1965 (1998). “Standard specification for nighttime photometric performance of retroreflective pedestrian markings for visibility enhancement,” ASTM E1501 (1999). “Standard specification for photoluminescent (phosphorescent) safety markings,” ASTM E2072 (2000). “Standard specification for physical characteristics of nonconcentrator terrestrial photovoltaic reference cells,” ASTM E1040 (1998). “Standard specification for retroreflective sheeting for traffic control,” ASTM D4956 (2001). “Standard specification for silvered flat glass mirror,” ASTM C1503 (2001). “Standard specification for solar simulation for terrestrial photovoltaic testing.” ASTM E927 (1997). “Standard tables for references solar spectral irradiance at air mass 1.5: direct normal and hemispherical for a 37° tilted surface,” ASTM G159 (1998).
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“Standard terminology of appearance,” ASTM E284 (2001). “Standard terminology relating to molecular spectroscopy,” ASTM E131 (2000). “Standard terminology relating to photovoltaic solar energy conversion,” ASTM E1328 (1999). “Standard terminology relating to solar energy conversion,” ASTM E772 (1993). Standard test method for 20-deg specular gloss of waxed paper,” ASTM D1834 (2000). Standard test method for 45-deg specular gloss of ceramic materials,” ASTM C346 (1998). Standard test method for 60-deg specular gloss of emulsion floor polish,” ASTM D1455 (1997). “Standard test method for calibration of a spectroradiometer using a standard source of irradiance,” ASTM G138 (1996). “Standard test method for calibration of heat transfer rate calorimeters using a narrow-angle blackbody radiation facility,” ASTM E638 (1992). “Standard test method for calibration of narrow- and broad-band ultraviolet radiometers using a spectroradiometer,” ASTM G130 (1995). “Standard test method for calibration of a pyranometer using a pyrheliometer,” ASTM G151 (2000). “Standard test method for color and color-difference measurement by tristimulus (filter) colorimetry,” ASTM E1347 (1997) (formerly E97). “Standard test method for determining the linearity of a photovoltaic device parameter with respect to a test parameter,” ASTM E1143 (1994). “Standard test method for estimating stray radiant power ratio of spectrophotometers by the opaque filter method,” ASTM E387 (1995). “Standard test method for field measurement of raised retroreflective pavement markers using a portable retroreflectometer,” ASTM E1696 (2001). “Standard test method for haze and luminous transmittance of transparent plastics,” ASTM D1003 (2000). “Standard test method for identifying fluorescence in object-color specimens by spectrophotometry,” ASTM E1247 (2000). “Standard test method for luminous reflectance factor of acoustical materials by use of integrating-sphere reflectometers,” ASTM E1477 (1998). “Standard test method for measuring and calculating emittance of architectural flat glass products using spectrometric measurements,” ASTM E1585 (1993). “Standard test method for minimum detectable temperature difference for thermal imaging systems,” ASTM E1311 (1999). “Standard test method for noise equivalent temperature difference of thermal imaging systems,” ASTM E1543 (2000).
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“Standard test method for obtaining colorimetric data from a visual display unit by spectroradiometry,” ASTM E1336 (1996). “Standard test method for obtaining colorimetric data from a visual display unit using tristimulus colorimeters,” ASTM E1455 (1997). “Standard test method for obtaining spectroradiometric data from radiant sources for colorimetry,” ASTM E1341 (1996). “Standard test method for photopic luminance of photoluminescent (phosphorescent) markings,” ASTM E2073 (2000). “Standard test method for radiation thermometer (single waveband type),” ASTM E1256 (1988). “Standard test method for reflection haze of high-gloss surfaces,” ASTM D4039 (1999). “Standard test method for reflectance factor and color by spectrophotometry using bidirectional geometry,” ASTM E1349 (1998). “Standard test method for solar absorptance, reflectance and transmittance of materials using spectrophotometers with integrating spheres,” ASTM E903 (1988). “Standard test methods for solar energy transmittance and reflectance (terrestrial) of sheet materials,” ASTM E424 (1993). “Standard test method for solar absorptance, reflectance, and transmittance of materials using integrating spheres,” ASTM E903 (1996). “Standard test method for spectral bandwidth and wavelength accuracy of fluorescence spectrometers,” ASTM E388 (1998). “Standard test method for specular gloss,” ASTM D523 (1999). “Standard test method for specular gloss of paper and paperboard at 75°,” ASTM D1223 (1998). “Standard test method for total luminous reflectance factor by use of 30/t integrating-sphere geometry,” ASTM E1651 (1999). “Standard test method for transfer of calibration from reference to field radiometers,” ASTM E824 (1994). “Standard test method for transmittance and color by spectrophotometry using hemispherical geometry,” ASTM E1348 (1996). “Standard test method for transparency of plastic sheeting,” ASTM D1746 (1997). “Standard test method for visual evaluation of gloss differences between surfaces of similar appearance,” ASTM D4449 (1999). “Standard test method for total hemispherical emittance of surfaces from 20 to 1400° C,” ASTM C835 (2000). “Standard test method for brightness of pulp, paper, and paperboard (directional reflectance at 457 nm),” ASTM D985 (1997).
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“Standard test method for calculation of color differences from instrumentally measured color coordinates,” ASTM D2244 (2000). “Standard test method for calibration of pyrheliometers by comparison to reference pyrheliometers,” ASTM E816 (1995). “Standard test method for calibration of a pyranometer using a pyrheliometer,” ASTM G167 (2000). “Standard test method for calibration of a spectroradiometer using a standard source of irradiance,” ASTM G138 (1996). “Standard test method for calibration of narrow- and broad-band ultraviolet radiometers using a spectroradiometer,” ASTM G130 (1995). “Standard test method for calibration of primary non-concentrator terrestrial photovoltaic reference cells using a tabular spectrum,” ASTM E1125 (1999). “Standard test method for calibration of reference pyranometers with axis tilted by the shading method,” ASTM E941 (1999). “Standard test method for calibration of silicon non-concentrator photovoltaic primary reference cells under global irradiation,” ASTM E1039 (1999). “Standard test method for calorimetric determination of hemispherical emittance and the ratio of solar absorptance to hemispherical emittance using solar simulation,” ASTM E434 (1996). “Standard test method for coefficient of retroreflection of retroreflective sheeting utilizing the coplanar geometry,” ASTM E810 (2001). “Standard test method for color and color-difference measurement by tristimulus (filter) colorimetry,” ASTM E1347 (1997). “Standard test method for color of liquids using tristimulus colorimetry,” ASTM D5386 (2000). “Standard test method for conducting aqueous direct photolysis tests,” ASTM E896 (1997). “Standard test method for detecting delaminations in bridge decks using infrared thermography,” ASTM D4788 (1997). “Standard test method for determining solar or photopic reflectance, transmittance, and absorptance of materials using a large diameter integrating sphere,” ASTM E1175 (1996). “Standard test method for determining the linearity of a photovoltaic device parameter with respect to a test parameter,” ASTM E1143 (1999). “Standard test method for diffuse light transmission factor of reinforced plastics panels,” ASTM D1494 (1997). “Standard test method for electrical performance of photovoltaic cells using reference cells under simulated sunlight,” ASTM E948 (1995). “Standard test method for evaluating color image output from color printers and copiers,” ASTM F1206 (2000).
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“Standard test method for evaluation of color for thermoplastic traffic marking materials,” ASTM D4960 (1998). “Standard test method for evaluation of visual color difference with a gray scale,” ASTM D2616 (1996). “Standard test method for haze and luminous transmittance of transparent plastics,” ASTM D1003 (2000). “Standard test method for hiding power of paints by reflectometry,” ASTM D2805 (1996). “Standard test method for identifying fluorescence in object-color specimens by spectrophotometry,” ASTM E1247 (2000). “Standard test method for linearity of fluorescence measuring systems,” ASTM E578 (2001). “Standard test method for luminous reflectance factor of acoustical materials by use of integrating-sphere reflectometers,” ASTM E1477 (1998). “Standard test method for measuring total-radiance temperature of heated surfaces using a radiation pyrometer,” ASTM E639 (1996). “Standard test method for measurement and calculation of reflecting characteristics of metallic surfaces using integrating sphere instruments,” ASTM E429 “Standard test method for measurement of high-visibility retroreflective-clothing marking material using a portable retrorelectometer,” ASTM E1809 (1996). “Standard test method for measurement of retroreflective pavement marking materials with cen-prescribed geometry using a portable retroreflectometer,” ASTM E1710 (1997). “Standard test method for measurement of retroreflective signs using a portable retroreflectometer,” ASTM E1709 (2000). “Standard test method for minimum detectable temperature difference for thermal imaging systems,” ASTM E1311 (1999). “Standard test method for minimum resolvable temperature difference for thermal imaging systems,” ASTM E1213 (1997). “Standard test method for noise equivalent temperature difference of thermal imaging systems,” ASTM E1543 (2000). “Standard test method for normal spectral emittance at elevated temperatures,” ASTM E307 (1996). “Standard test method for normal spectral emittance at elevated temperatures of nonconducting specimens,” ASTM E423 (1996). “Standard test method for obtaining colorimetric data from a visual display unit by spectroradiometry,” ASTM E1336 (1996). “Standard test method for opacity of paper (15° diffuse illuminant A, 89% reflectance backing and paper backing),” ASTM D589 (1997).
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“Standard test method for photoelastic measurements of birefringence and residual strains in transparent or translucent plastic materials,” ASTM D4093 (1995). “Standard test method for reflectance factor and color by spectrophotometry using hemispherical geometry,” ASTM E1331 (1996). “Standard test method for reflectance factor and color by spectrophotometry using bidirectional geometry,” ASTM E1349 (1998). “Standard test method for reflection haze of high-gloss surfaces,” ASTM D4039 (1999). “Standard test method for relative tinting strength of aqueous ink systems by instrumental measurement,” ASTM D6531 (2000). “Standard test method for relative tinting strength of white pigments by reflectance measurements,” ASTM D2745 (2000). “Standard test method for retroreflectance of horizontal coatings,” ASTM D4061 (2000). “Standard test method for solar absorptance, reflectance, and transmittance of materials using integrating spheres,” ASTM E903 (1996). “Standard test method for solar photometric transmittance of sheet materials using sunlight,” ASTM E972 (1996). “Standard test method for solar transmittance (terrestrial) of sheet materials using sunlight,” ASTM E1084 (1996). “Standard test method for spectral bandwidth and wavelength accuracy of fluorescence spectrometers,” ASTM E388 (1998). “Standard test method for specular gloss,” ASTM D523 (1999). “Standard test method for specular gloss of glazed ceramic whitewares and related products,” ASTM C584 (1999). “Standard test method for total luminous reflectance factor by use of 30/t integrating-sphere geometry,” ASTM E1651 (1999). “Standard test method for transmittance and color by spectrophotometry using hemispherical geometry,” ASTM E1348 (1996). “Standard test method for transparency of plastic sheeting,” ASTM D1746 (1997). “Standard test methods for continuous measurement of ozone in ambient, workplace, and indoor atmospheres (ultraviolet absorption),” ASTM D5156 (1995). “Standard test methods for measurement of gloss of high-gloss surfaces by goniophotometry,” ASTM E430 (1997). “Standard test methods for measuring and compensating for emissivity using infrared imaging radiometers,” ASTM E1933 (1999). “Standard test methods for measuring and compensating for reflected temperature using infrared imaging radiometers,” ASTM E1862 (1997).
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“Standard test methods for measuring and compensating for transmittance of an attenuating medium using infrared imaging radiometers,” ASTM E1897 (1997). “Standard test methods for measuring optical reflectivity of transparent materials,” ASTM E1682 (1996). “Standard test methods for measuring spectral response of photovoltaic cells,” ASTM E1021 (1995). “Standard test methods for measuring total-radiance temperature of heated surfaces using a radiation pyrometer” ASTM E639 (1990). “Standard test methods for measurement of gloss of high-gloss surfaces by goniophotometry,” ASTM E430 (1997). “Standard test methods for minimum detectable temperature difference for thermal imaging systems” ASTM E1311 (1993). “Standard test methods for minimum resolvable temperature difference for thermal imaging systems” ASTM E1213 (1992). “Standard test methods for noise equivalent temperature difference of thermal imaging systems” ASTM E1543 (1994). “Standard test methods for radiation thermometers (single waveband type),” ASTM E1256 (1995). “Standard test methods for solar energy transmittance and reflectance (terrestrial) of sheet materials,” ASTM E424 (1993). “Standard test methods for total normal emittance of surfaces using inspectionmeter techniques,” ASTM E408 (1996).
BIPM The BIPM (Bureau International des Poids et Mesures)v is an international institute operating under the supervision of the Comite International des Poids et Mesures (CIPM). It is charged with the establishment and maintenance of reference standards, the organization of international comparisons and carrying out of calibrations, and fundamental investigations that may result in better reference standards or measurement techniques. The prototype kilogram is located here. Some of their publications include: Principles Governing Photometry (1983). The International System of Units (SI), BIPM, 7th Edition (1998). “Radiation Thermometry,” Chapter 6 in Supplementary Information for the International Temperature Scale of 1990, BIPM (1990). International Vocabulary of Basic and General Terms in Metrology, joint BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, OIML Standard, BIPM (1993).
v
www.bipm.fr
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Guide to the Expression of Uncertainty in Measurement, joint BIPM, IEC, IFCC, ISO, IUPAC, IUPAP, OIML Standard, BIPM (1993).
CIE The Commission Internationale de L’Eclairagevi has numerous technical committee reports that are relevant. Check into their web page for more information. Division 1 is involved with vision and color, while Division 2 deals with the measurement of light and radiation. The U.S. National Committee of the CIE is at http://www.cie-usnc.org. Some pertinent reports, primarily from Division 2, are: 13.3 Method of Measuring and Specifying Colour Rendering of Light Sources (1995). 15.2 Colorimetry, 2nd Ed. (1986). 17.4 International Lighting Vocabulary, 4th Ed. (Joint publication IEC/CIE) (1987). 18.2 The Basis of Physical Photometry, 2nd Ed. (1983). 38 “Radiometric and photometric characteristics of materials and their measurement,” (1977). 41 “Light as a true visual quantity: principles of measurement,” (1978). 44 “Absolute methods for reflection measurements,” (1979). 46 “A review of publications on properties and reflection values of material reflection standards,” (1979). 53 “Methods of characterizing the performance of radiometers and photometers,” (1982). 54 “Retroreflection: definition and measurement,” (2001). 59 “Polarization: definitions and nomenclature, instrument polarization,” (1984). 63 “The spectroradiometric measurement of light sources,” (1984). 64 “Determination of the spectral responsivity of optical radiation detectors,” (1984). 65 “Electrically calibrated thermal detectors of optical radiation (absolute radiometers)” (1985). 69 “Methods of characterizing illuminance meters and luminance meters: Performance, characteristics and specifications,” (1987). 70 “The measurement of absolute luminous intensity distributions,” (1987). 75 “Spectral luminous efficiency functions based upon brightness matching for monochromatic point sources, 20 and 100 fields,” (1988). vi
www.cie.co.at/ Write to Thomas Lemons, TLA- Lighting Consultants Inc., 7 Pond St., Salem, MA 01970 or contact Tel: (508) 745-6870, Fax: (508) 741-4420 for a listing of current publications and pricing.
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76 “Intercomparison on measurement of (total) spectral radiance factor of luminescent specimens,” (1988). 78 “Brightness-luminance relations: classified bibliography,” (1988). 81 “Mesopic photometry: history, special problems and practical solutions,” (1989). 84 “Measurement of luminous flux,” (1989). 85 “Solar spectral irradiance,” (1989). 86 “CIE 1988 2 spectral luminous efficiency function for photopic vision,” (1990). 87 “Colorimetry of self-luminous displays: a bibliography,” (1990). 96 “Electric light sources, state of the art—1991,” (1992). 105 “Spectroradiometry of pulsed optical radiation sources,” (1993). 114 CIE Collection in Photometry and Radiometry (1994). 121 “The photometry and goniophotometry of luminaires,” (1996). 125 “Standard erythema dose, a review,” (1997). 127 “Measurement of LEDs,” (1997). 130 “Practical methods for the measurement of reflectance and transmittance,” (1998). 141 “Testing of supplementary systems of photometry,” (2001).
IES The Illuminating Engineering Society of North America (IESNA)vii has an extensive list of publications dealing with illumination. Their IESNA Lighting Handbook, 9th Ed. is the definitive reference. The following are procedures dealing with photometric measurements of various lamps and luminaires: LM-9 LM-10 LM-11 LM-20 LM-31 LM-35 LM-41 LM-44 LM-45
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Electrical and Photometric Measurements of Fluorescent Lamps Photometric Testing of Outdoor Fluorescent Luminaires Photometric Testing of Searchlights Photometric Testing of Reflector-Type Lamps Photometric Testing of Roadway Luminaires Photometric Testing of Floodlights Using High-Intensity Discharge Lamps or Incandescent Filament Lamps Photometric Testing of Indoor Fluorescent Luminaires Method for Total and Diffuse Reflectometry (1985) Electrical and Photometric Measurements of General Service Incandescent Filament Lamps
www.iesna.org
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LM-46 LM-50 LM-51 LM-52 LM-54 LM-55 LM-58 LM-59 LM-63 LM-64 LM-66 LM-68 LM-70 LM-72 RP-16
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Photometric Testing of Indoor Luminaires Using HID Discharge or Incandescent Filament Lamps Photometric Measurement of Roadway Lighting Installations Electrical and Photometric Measurements of High-Intensity Discharge Lamps Photometric Measurement of Roadway Sign Installations Lamp Seasoning Measurement of Ultraviolet Radiation from Light Sources Spectroradiometric Measurements Electrical and Photometric Measurements of Low-Pressure Sodium Lamps Standard File Format for Electronic Transfer of Photometric Data Photometric Measurements of Parking Areas Electrical and Photometric Measurements of Compact Fluorescent Lamps Photometric Evaluation of Vehicle Traffic Control Signal Heads Near-Field Photometry Directional Positioning of Photometric Data Nomenclature and Definitions for Illuminating Engineering (ANSI Approved)
ISO The International Standards Organization.viii ISO 2470: Brightness for Fluorescent Materials (1999). ISO/CIE 10526: CIE standard illuminants for colorimetry (CIE S005/E-1998) (1999). ISO/CIE 10527: CIE standard colorimetric observers (CIE S002, 1986) (1991). ISO/CIE 15469: Spatial distribution of daylight—CIE standard overcast sky and clear sky (CIE S003, 1996) (1997). ISO/CIE 16508: Road traffic lights—Photometric properties of 200 mm round signals (CIE S006) (1999). ISO17166: Erythema reference action spectrum and standard erythema dose (CIE S007) (1999). ISO 11475: Paper and board—Determination of CIE whiteness, D65/10 degrees (outdoor daylight) (1999).
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ISO 11476: ISO 8599: ISO 9845-1:
ISO 9022-9: ISO 9022-17: ISO 9050:
ISO 9059: ISO 9060:
ISO 9488: ISO 9846: ISO 9847: ISO/TR 9901: ISO 6: ISO 2240: ISO 8478: ISO 12232:
Appendix J
Paper and board—Determination of CIE-whiteness, C/2 degrees (indoor illumination conditions) (2000). Optics and optical instruments—Contact lenses—Determination of the spectral and luminous transmittance (1994). Solar energy—Reference solar spectral irradiance at the ground at different receiving conditions—Part 1: Direct normal and hemispherical solar irradiance for air mass 1,5 (1992). Optics and optical instruments—Environmental test methods— Part 9: Solar radiation (1994). Optics and optical instruments—Environmental test methods— Part 17: Combined contamination, solar radiation (1994). Glass in building—Determination of light transmittance, solar direct transmittance, total solar energy transmittance and ultraviolet transmittance, and related glazing factors (1990). Solar energy—Calibration of field pyrheliometers by comparison to a reference pyrheliometer (1990). Solar energy—Specification and classification of instruments for measuring hemispherical solar and direct solar radiation (1990). Solar energy—Vocabulary (1999). Solar energy—Calibration of a pyranometer using a pyrheliometer (1993). Solar energy—Calibration of field pyranometers by comparison to a reference pyranometer (1992). Solar energy—Field pyranometers—Recommended practice for use (1990). Photography—Black-and-white pictorial still camera negative film/process systems—Determination of ISO speed (1993). Photography—Colour reversal camera films—Determination of ISO speed (1994). Photography—Camera lenses—Measurement of ISO spectral transmittance (1996). Photography—Electronic still-picture cameras—Determination of ISO speed (1998).
IEC Founded in 1906, the International Electrotechnical Commission (IEC)ix is the world organization that prepares and publishes international standards for all ix
IEC, 3, Rue de Varembe, PO Box 131, 1211 Geneva 20, Switzerland. Tel: +41 22 919 02 11, Fax: +41 22 919 03 00, Website: http://www.iec.ch.
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electrical, electronic, and related technologies. The IEC was founded as a result of a resolution passed at the International Electrical Congress held in St. Louis, Missouri in 1904. The membership consists of more than 50 participating countries, including all the world’s major trading nations and a growing number of industrializing countries. Multimedia systems and equipment —Colour measurement and IEC management Part 2-1: Colour management—Default RGB 61966-2-1 colour space—sRGB Ed. l: 1999 IEC 61966-3 Multimedia systems and equipment —Colour measurement and Ed. l: 2000 management Part 3: Equipment using cathode ray tubes. IEC 61966-4 Multimedia systems and equipment —Colour measurement and Ed. 1: 2000 management Part 4: Equipment using liquid crystal display panels. IEC 61966-5 Multimedia systems and equipment —Colour measurement and Ed. 1: 2000 management Part 5: Equipment using plasma display panels. IEC 61966-8 Multimedia systems and equipment —Colour measurement and Ed. 1: 2001 management Part 8: Multimedia colour scanners. IEC 61966-9 Multimedia systems and equipment —Colour measurement and Ed. l: 2000 management Part 9: Digital cameras.
NVLAP The National Voluntary Laboratory Accreditation Program.x Established in 1976 and administered by the National Institute of Standards and Technology (NIST), NVLAP is an unbiased government-based third-party system for accrediting calibration laboratories and testing laboratories found competent to perform specific tests or calibrations. Criteria for NVLAP accreditation are published in the Code of Federal Regulations (Title 15, Part 285) and encompass the requirements of ISO/IES Guide 25 and the relevant requirements of ISO 9002. NVLAP accreditation is available to commercial laboratories, manufacturers’ in-house laboratories, university laboratories, federal, state, and local government laboratories, and foreign-based laboratories. “Procedures and General Requirements,” NIST Handbook 150, National Voluntary Laboratory Accreditation Program (NVLAP), C. D. Faison et al, Eds. (February 2006).
x
National Institute of Standards and Technology, National Voluntary Laboratory Accreditation Program, 100 Bureau Drive, MS 2140, Gaithersburg, Maryland 20899-2140, Telephone: 301-9754016, Fax: 301-926-2884, E-mail:
[email protected], Website: http://www.ts nist.gov/nvlap.
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Appendix J
“Energy Efficient Lighting Products,” NIST Handbook 150-1, National Voluntary Laboratory Accreditation Program (NVLAP), C. C. Miller and L. I. Knab, Eds. (March 2008). xi NVLAP identifies its accredited laboratories in a published directory, NIST Special Publication 810, and on their website.
SAE SAE International, formerly the Society of Automotive Engineers,xii is a nonprofit educational and scientific organization dedicated to advancing mobility technology to better serve humanity. Nearly 70,000 engineers and scientists who are SAE members develop technical information on all forms of self-propelled vehicles including automobiles, trucks and buses, off-highway equipment, aircraft, aerospace vehicles, marine, rail, and transit systems. SAE disseminates this information through meetings, books, technical papers, magazines, standards, reports, professional development programs, and electronic databases. Here is a selection of their relevant standards, mostly dealing with lighting and its measurement. HS-34 J387 J1330 J575 J 1383 J2217
SAE Ground Vehicle Lighting Standards Manual (1999). “Terminology—Motor Vehicle Lighting” (1995). “Photometry Laboratory Accuracy Guidelines” (1994). “Test Methods and Equipment for Lighting Devices and Components for Use on Vehicles Less than 2032 mm in Overall Width” (1992). “Performance Requirements for Motor Vehicle Headlamps” (1996). “Photometric Guidelines for Instrument Panel Displays that Accommodate Older Drivers” (1991).
TAPPI The Technical Association of the Pulp and Paper Industry.xiii TAPPI is the leading technical association for the worldwide pulp, paper, and converting industry. TAPPI provides its members rapid access to: (1) the largest international group of technically experienced people in the industry, (2) the most comprehensive collection of reliable technical information and knowledge in the industry, and (3) the highest quality products and services created to meet the needs of people who solve technical problems in the industry. Among their documentary standards are the following: T-425 Opacity of paper (15/d geometry, Illuminant A/2, 89% reflectance backing and paper backing) (1996). xi
Handbook 150 and 150-1 are available on the NVLAP website at http://www.ts.nist.gov/nvlap. www.sae.org xiii http://www.tappi.org xii
Documentary Standards for Radiometry and Photometry
T-452 T-480 T-560 T-562 T-1212 T-1213 T-1214 T-1215 T-1216 T-1217 T-1218
339
Brightness of pulp, paper and paperboard (directional reflectance at 457 nm) (1998). Specular gloss of paper and paperboard at 75 degrees (1999). CIE whiteness and tint of paper and paperboard (d/0 geometry, C/2 illuminant/observer) (1996). CIE whiteness and tint of paper and paperboard (45/0 geometry, C/2 illuminant/observer) (1996). Light sources for evaluating papers, including those containing fluorescent whitening agents (1998). Optical measurements terminology (related to appearance evaluation of paper) (1998). Interrelation of reflectance; reflectivity; TAPPI opacity; scattering, s; and absorption, k (1998). The determination of instrumental color differences (1998). Indices for whiteness, yellowness, brightness, and luminous reflectance factor (1998). Photometric linearity of optical properties instruments (1998). Calibration of reflectance standards for hemispherical geometry (1998).
Appendix K
Radiometry and Photometry Bibliography In 1969 Fred Nicodemus authored a paper “Optical resource letter on radiometry” (JOSA 59, 243). It was reprinted in an AIP Radiometry—Selected Reprints collection in 1971. This bibliography is intended to update and supplement the 1969 version. The topic breakdown is more in line with the order of topics in this book than the original. Individual papers are for the most part bypassed in favor of books, significant book chapters, monographs, or reprint collections.
Symbols, Units, and Terminology American National Standard Nomenclature and Definitions for Illuminating Engineering. ANSI, Standard ANSI/IESNA RP-16 96 (1996). International Lighting Vocabulary, CIE Publication 17 (1970). “Quantities and units—Part 6. Light and related electromagnetic radiations,” ISO Standards Handbook, Quantities and Units 389.15 (1993). Symbols, Units and Nomenclature in Physics, International Union of Pure and Applied Physics (1987). C. L. Wyatt, V. Privalsky, and R. T. Datlu, Recommended Practice: Symbols, Units and Uncertainty Analysis for Radiometric Sensor Calibration, NIST Handbook 152 (1998).
General R. W. Boyd, Radiometry and the Detection of Optical Radiation, John Wiley & Sons, New York (1983). Good for the theoretical aspects of radiation geometry, along with several other topics. M. A. Bramson, Infrared: A Handbook for Applications, Plenum, New York (1966). F. C. Grum, and R. J. Becherer, Optical Radiation Measurements I. Radiometry, Academic Press, New York (1979). The best all-around book on radiometry to date. 341
342
Appendix K
A. Hadni, Essentials of Modern Physics Applied to the Study of the Infrared, Pergamon, Oxford Univ. Press, New York (1967). M. R. Holter, S. Nudelman, G. H. Suits, W. L. Wolfe and G. J. Zissis, Fundamentals of Infrared Technology, Macmillan, New York (1962). J. A. Jamieson, R. H. McFee, G. N. Plass, R. H. Grube, and R. G. Richards, Infrared Physics and Engineering, McGraw-Hill, New York (1963). P. W. Kruse, L. D. McGlaughlin, and R. B. McQuistan, Elements of Infrared Technology, John Wiley & Sons, New York (1962). W. R. McCluney, Introduction to Radiometry and Photometry, Artech House, Boston (1994). A recent entry, again slightly slanted to the author’s (Palmer) specialty of solar energy applications. Both elementary and thorough. I. J. Spiro and M. Schlessinger, Infrared Technology Fundamentals, Marcel Dekker, New York (1989). W. L Wolfe and G. Zissis, The Infrared Handbook, Office of Naval Research, Washington, D.C. (1978). The most bang for your buck! At $60, everybody should have one! Available from SPIE. W. L. Wolfe, Introduction to Radiometry, SPIE Press, Bellingham, Washington (1998). Uneven and terse in spots, still recommended. He was my (Palmer) mentor! E. F. Zalewski, “Radiometry and Photometry,” Chapter 24 in Handbook of Optics, Vol. II, McGraw-Hill, New York (1995). An excellent review.
Geometric Radiation Transfer A. Gershun, “The Light Field,” Moscow, 1936, trans. P. Moon and G. Timoshenko, J. Math. Phys. 18, 51–151(1939). H. C. Hottel and A. F. Sarofim, Radiative Transfer, McGraw-Hill, New York (1967). J. R. Howell, A Catalog of Radiation Configuration Factors, McGraw-Hill, New York (1982). F. E. Nicodemus et al., Self-Study Manual on Optical Radiation Measurements, NBS Technical Note 910–xx. NIST, Washington (various dates). A series that is rather theoretical with increasing coverage. Some may be out of print. Check GPO for availability. R. Siegel and J. R. Howell, Thermal Radiation Transfer, Hemisphere, Washington, D.C. (1981). Intended for mechanical and heat transfer engineers (uses non-SI units like BTUs, degrees Rankine, and the wrong intensity) and highly detailed, this book is the best compendium on radiative transfer. E. M. Sparrow and R. D. Cess, Radiation Heat Transfer, Brooks/Cole, California (1970). J. H. Taylor, Radiation Exchange, Academic Press, New York (1990).
Radiometry and Photometry Bibliography
343
Radiosity and Ray Tracing I. Ashdown, Radiosity: A Programmer’s Perspective, John Wiley & Sons, New York (1994). M. F. Cohen and J. R. Wallace, Radiosity and Realistic Image Syntheses, Academic Press, New York (1993).
Optical Radiation Sources F. E. Carlson and C. N. Clark, Light Sources for Optical Devices, Chapter 2 in Applied Optics and Optical Engineering, Vol. 1, R. Kingslake, Ed., Academic Press, New York (1975). K. L. Coulson, Solar and Terrestrial Radiation, Academic Press, New York (1975). J. E. Eby and R. E. Levin, Incoherent Light Sources, Chapter 1 in Applied Optics and Optical Engineering, Vol. 7, R. R. Shannon and J. Wyant, Eds., Academic Press, New York (1975). A. S. Green, Ed. The Middle Ultraviolet: Its Science and Technology, John Wiley & Sons, New York (1966). F. Grum and R. J. Becherer, Radiometry, Vol. 1 in Optical Radiation Measurements, Academic Press, New York (1979). H. Hewitt and A. S. Vause, Lamps and Lighting, Elsevier, New York (1966). M. Iqbal, An Introduction to Solar Radiation, Academic Press, New York (1983). P. A. Jacobs, Thermal Infrared Characterization of Ground Targets and Backgrounds, SPIE Press, Bellingham, Washington (1996). D. Kryskowski and G. H. Suits, “Natural sources,” Chapter 3 in Sources of Radiation, G. J. Zissis, Ed., Vol. 1 of The Infrared & Electro-Optical Handbook, SPIE Press, Bellingham, Washington (1993). A. J. LaRocca, “Artificial sources,” Chapter 2 in Sources of Radiation, G. J. Zissis, Ed., Vol. 1 of The Infrared & Electro-Optical Handbook, SPIE Press, Bellingham, Washington (1993). A. J. LaRocca, “Artificial sources,” Chapter 10 in Optical Sources, G. J. Zissis, Ed., Vol. 1, Part 4 Handbook of Optics, McGraw Hill, New York (1995). M. Luckiesh, Applications of Germicidal, Erythemal and Infrared Energy, Van Nostrand, New York (1946). D. Malacara, “Light sources,” Chapter 5 In Geometrical and Instrumental Optics, Academic Press, Boston (1988). P. Moon, The Scientific Basis of Illuminating Engineering, McGraw-Hill, New York (1936), reprinted by Dover, New York (1961). J. B. Murdoch, Illumination Engineering: From Edison’s Lamp to the Laser, Macmillan, New York (1985).
344
Appendix K
RCA Electro-Optics Handbook, RCA, Lancaster PA (1974). Now available from Burle Industries. M. Rea, Ed., Lighting Handbook: Reference and Application, 8th Ed., Illuminating Engineering Society of North America (1993). J. C. Richmond and F. E. Nicodemus, “Blackbodies, blackbody radiation, and temperature scales,” NBS Self-Study Manual on Optical Radiation Measurements, Part 1, Chapter 12, GPO (1985). W. T. Silfvast, “Lasers,” Chapter 11 in Handbook of Optics, Vol. 1, Part 4. Optical Sources, McGraw-Hill, New York (1995). G. H. Suits, “Natural sources,” Chapter 3 in The Infrared Handbook, ERIM (1982). Distributed By SPIE. R. H. Weissman, “Light emitting diodes,” Chapter 12 in Handbook of Optics, Vol. 1, Part 4. Optical Sources, McGraw-Hill, New York (1995). G. J. Zissis and A. J. Larocca, “Optical Radiators and Sources,” Chapter 3 in Handbook Of Optics, McGraw-Hill, New York (1978).
Detectors A. Ambroziak, Semiconductor Photoelectric Devices, Gordon & Breach, New York (1969). D. F. Barbe, Ed., Charge-Coupled Devices, Springer-Verlag, New York (1980). C. J. Bartelson, F. C. Grum, Optical Radiation Measurements Vol. 5: Visual Measurements, Academic Press, New York (1984). J. D. E. Beynon and D. R. Lamb, Charge-Coupled Devices and their Applications, McGraw-Hill, New York (1980). L. Biberman and S. Nudelman, Photoelectronic Imaging Devices, Plenum, New York (1970). Two volumes. R. M. Boynton, Human Color Vision, Holt, Rinehart & Winston, New York (1979). W. Budde, Optical Radiation Measurements Vol 4: Physical Detectors of Optical Radiation, Academic Press, New York (1983). The best practical book on detectors and their characterization, slanted a bit towards the visible spectrum. C. Buil, CCD Astronomy, Willman-Bell, Richmond, Virginia (1991). A. Chappell, Optoelectronics: Theory and Practice, McGraw-Hill, New York (1978). I. P. Csorba, Image Tubes, Howard W. Sams Engineering-Reference Book Series, Indianapolis, Indiana (1985). P. N. J. Dennis, Photodetectors, Plenum, New York (1986). E. L. Dereniak and G. Boreman, Infrared Detectors and Systems, John Wiley & Sons, New York (1996).
Radiometry and Photometry Bibliography
345
E. L. Dereniak and D. Crowe, Optical Radiation Detectors, John Wiley & Sons, New York (1984). Good general book, slanted towards the infrared. S. Donati, Photodetectors: Devices, Circuits and Applications, Prentice Hall, New Jersey (2000). Concise, accurate, highly recommended. M. J. Eccles, M. E. Sim, and K. P. Tritton, Low Light Level Detectors in Astronomy, Cambridge Univ. Press, New York (1983). R. W. Engstrom, RCA Photomultiplier Handbook, RCA (1980). Available from Burle Industries (http://www.burle.com/cgi-bin/byteserver.pl/pdf/Photo.pdf). G. C. Holst, CMOS/CCD Sensors and Camera Systems, SPIE Press, Bellingham, Washington (2007). R. D. Hudson and J. W. Hudson, Eds., Infrared Detectors, Hutchinson and Ross, Stroudsburg, Pennsylvania (1975). A collection of the more important papers to date. J. R. Janesick, Scientific Charge-Coupled Devices, SPIE Press, Bellingham, Washington (2001). R. J. Keyes, Ed., Optical and Infrared Detectors, Springer-Verlag, Bellingham, Washington (1980). I. S. McLean, Electronic Imaging in Astronomy, John Wiley & Sons, New York (1997). Photomultiplier Tube: Principle to Application, H. Kume, Ed., Hamamatsu Photonics K. K. (1994). S. O. Flyckt and C. Marmonier, Photomultiplier Tubes: Principles and Applications, Philips Photonics, Brive, France (2002). G. H. Rieke, Detection of Light from the Ultraviolet to the Submillimeter, Cambridge Univ. Press, New York (1994). A. Rose, Vision: Human and Electronic, Plenum, New York (1973). M. Ross, Laser Receivers, John Wiley & Sons, New York (1966). C. H. Séquin and M. F. Tomsett, Charge Transfer Devices, Academic Press, New York (1975). R. A. Smith, F. E. Jones, and R. P. Chasmar, The Detection and Measurement of Infra-red Radiation, Oxford Univ. Press, New York (1957). A. H. Sommer, Photoemissive Materials, John Wiley & Sons, New York (1968). Reprinted by Krieger, Huntington, New York (1980). J. D. Vincentm, Fundamentals of Infrared Detector Operation and Testing, John Wiley & Sons, New York (1990). Separate chapters on cryogenics, vacuum systems, and detector electronics. Answers many of those nagging questions. Highly recommended. A. T. Young, “Photomultipliers, their causes and cures,” Chapter 1 in Methods of Experimental Physics: Astrophysics, N. Carleton Ed., Vol. 12, Academic Press, New York (1974).
346
Appendix K
The major handbooks offer one or more chapters dealing with optical radiation detectors. These include the following: J. S. Accetta and D. L. Shumaker, Eds., Infrared and Electro-Optical Systems Handbook, SPIE Press, Bellingham, Washington (1993). See Vol. 3, Chapter 4. M. Bass, Ed. Handbook of Optics, Vol. 1, McGraw-Hill, New York (1995). Parts 5, 6, and 7 contain chapters 15 through 25, all pertinent to detectors and detection. W. G. Driscoll and W. Vaughn, Handbook of Optics, McGraw-Hill, New York (1978). Chapter 4. W. L. Wolfe, Ed., Handbook of Military Infrared Technology, ONR, Washington (1965). Chapters 11 & 12. W. L. Wolfe and G. Zissis, Eds., The Infrared Handbook, ERIM and SPIE (1978). Chapters 11 through 16. Several books in the series Semiconductors and Semimetals, R. K. Willardson and A. C. Beer, Eds., are relevant. Volumes 5 and 12 both treat infrared detectors, and Vol. 11 deals exclusively with solar cells. Volume 47 deals with uncooled infrared imaging array systems.” Similarly, the series Advances in Electronics and Electron Physics is rich in pertinent articles. Numerous volumes deal with imaging detector conference proceedings, while others have significant feature articles. Most notable are Vols. 34 and 55. Another rich source for detector information, and probably the best for assessment of the current state of art, are the Proceedings of the various conferences of SPIE (see p. 355), available on SPIE’s digital library.i They have several major conventions per year, each having one or more conferences on detectors. Compilations of the best proceedings papers along with seminal papers are often gathered in their “Milestones” series. Several detector manufacturers publish manuals, collections of applications notes, etc. Particularly attractive are the photomultiplier tube books by Burle (formerly RCA), Hamamatsu, and Philips, and the CCD books by EG&G Reticon and Fairchild. Data books by Dalsa, EG&G Vactec, Texas Instruments, Thompson CSF, etc., are also quite helpful.
Noise, Electronics, and Signal Processing D. A. Bell, Noise and the Solid State, John Wiley & Sons, New York (1985). E. R. Davies, Electronics, Noise and Signal Recovery, Academic Press, New York (1983). P. J. Fish, Electronic Noise and Low Noise Design, McGraw-Hill, New York (1994). i
http://spiedigitallibrary.aip.org/
Radiometry and Photometry Bibliography
347
T. M. Frederiksen, Intuitive IC Op Amps, National Semiconductor (1984). J. G. Graeme, Photodiode Amplifiers: Op-Amp Solutions, McGraw-Hill, New York (1996). M. S. Gupta, Ed., Electrical Noise: Fundamentals and Sources, IEEE (1977). P. Horowitz and W. Hill, The Art of Electronics, Cambridge Univ. Press, New York (1989). The best single book available for the broad field of electronics, my personal favorite! W. G. Jung, IC Op-amp Cookbook, Howard W. Sams (1980). More tutorial than Stout, with fewer useful circuits. C. D. Motchenbacher and J. A. Connelly, Low-Noise Electronic System Design, John Wiley & Sons, New York (1993). H. W. Ott, Noise Reduction Techniques in Electronic Systems, 2nd Ed., John Wiley & Sons, New York (1988). R. A. Pease, Troubleshooting Analog Circuits, Butterworth-Heinemann, Newton, Massachusetts (1991). D. F. Stout and M. Kaufman, Handbook of Operational Amplifier Circuit Design, McGraw-Hill, New York (1976). Excellent single-purpose reference book. A. Van der Ziel, Noise in Measurements, John Wiley & Sons, New York (1976). C. A. Vergers, Handbook of Electrical Noise: Measurement and Technology, 2nd Ed., Tab Books, Inc., Pennsylvania (1987). J. Williams, Analog Circuit Design: Art, Science and Personalities, ButterworthHeinemann, Newton, Massachusetts (1991). J. Williams, The Art and Science of Analog Circuit Design, ButterworthHeinemann, Newton, Massachusetts (1995). T. H. Wilmshurst, Signal Recovery, Adam Hilger, Bristol (1990). A. Yariv, Optical Electronics in Modern Communications, Oxford Univ. Press, New York (1997). Chapter 10 treats noise in optical detection and generation.
Radiometric Instruments B. N. Begunov, N. P. Zakaznov, S. I. Kiryushinand V. I. Kuzichev, Optical Instrumentation: Theory and Design, MIR, Moscow (1988). R. D. Hudson, Infrared System Engineering, John Wiley & Sons, New York (1969). Dated but still valuable. J. F. James and R. S. Sternberg, Design of Optical Spectrometers, Chapman & Hall, London (1969). K. Seyrafi, Ed., Engineering Design Handbook on Infrared Military Systems, United States Army Materiel Command, Pamphlet AMCP 706-127 (1971). Similar to Hudson but in MIL-format. Later modified and self published as Electro-Optical Systems Analysis, Electro-Optical Research Co, Los Angeles (1985).
348
Appendix K
W. L. Wolfe, Introduction to Infrared System Design, SPIE Press, Bellingham, Washington (1996). W. L. Wolfe, Introduction to Imaging Spectrometers, SPIE Press, Bellingham, Washington (1997). W. L. Wolfe, Infrared Design Examples, SPIE Press, Bellingham, Washington (1999). C. L. Wyatt, Radiometric Systems Design, Macmillan, New York (1987). More for the designer than the calibrator, but very useful. Later available as ElectroOptical System Design for Information Processing, McGraw-Hill, New York (1990). More for the system designer, but very useful.
Radiometric Measurements and Errors D. C. Baird, Experimentation: An Introduction to Measurement Theory and Experiment Design, Prentice-Hall, New York (1962). Y. Beers, Introduction to the Theory of Error, Addison-Wesley, Reading, Massachusetts (1957). P. R. Bevington and D.K. Robinson, Data Reduction and Error Analysis for the Physical Sciences, 2nd Ed., McGraw-Hill, New York (1992). Calibration: Philosophy in Practice, 2nd Ed., Fluke Corporation, Everett, Washington (1994). Available directly from them. J. P. Holman, Experimental Methods for Engineers, McGraw-Hill, New York (1978). J. Mandel, The Statistical Analysis of Experimental Data, Dover, New York (1984). S. L. Meyer, Data Analysis for Scientists and Engineers, John Wiley & Sons, New York (1975). S. Rabinovich, Measurement Errors: Theory and Practice, AIP Press (1995). B. N. Taylor & C. E. Kuyatt, Guidelines for Evaluating and Expressing the Uncertainty of NIST Measurement Results, NIST Technical Note 1297 (1994). Available on the web at http://physics.nist.gov/Pubs/guidelines/contents.html. J. R. Taylor, An Introduction to Error Analysis, 2nd Ed., University Science (1997). H. D. Young, Statistical Treatment of Experimental Data, McGraw-Hill, New York (1962).
Measurement of Radiometric Quantities G. Bauer, Measurement of Optical Radiations, Focal Press, London (1965). W. E. Forsythe, Ed., Measurement of Radiant Energy, McGraw-Hill, New York (1937).
Radiometry and Photometry Bibliography
349
H. J. Kostkowski, Reliable Spectroradiometry, Spectroradiometry Consulting, La Plata, Maryland 20646. Self-published lessons learned over some 40 years. Authoritative! D. Malacara, Physical Optics and Light Measurements, Academic Press, New York (1988). Chapter 6.
Photometry W. E. Barrows, Light, Photometry and Illuminating Engineering, McGraw-Hill, New York (1951). P. Bouguer, Essai d’optique sur la gradation de la lumiere, Paris (1729). It all started here! Translated into English by W. E. K. Middleton, The Gradation of Light, Toronto (1961). C. DeCusatis, Handbook of Applied Photometry, AIP Press (1997). Authoritative, with pertinent chapters written by technical experts at BIPM, CIE, and NIST. Primarily for visible radiation, mostly excellent. C. Fabry, “Photometrie,” Revue d’Optique, Paris (1927). H. A. E. Keitz, Light Calculations and Measurements, Cleaver Hume, London (1955), MacMillan, New York (1971). J. H. Lambert, Photometrie, Augsberg (1760). A beautiful English translation from the original Latin with copious notes by D. DiLaura was published in 2001, available from IESNA. Y. Ohno, “Radiometry and Photometry Review for Vision Optics,” Chapter 14 in Handbook of Optics III, McGraw-Hill, New York (2001). J. M. Palmer, “Radiometry and Photometry: Units and Conversions,” Chapter 7 in Handbook of Optics III, McGraw-Hill, New York (2001). A. Stimson, Photometry and Radiometry for Engineers, John Wiley & Sons, New York (1974). J. W. T. Walsh, Photometry, 3rd Ed., Constable (1958), reprinted by Dover, New York (1965). The standard reference since 1924.
Astronomical Measurement of Light I choose not to include these in the photometry section to avoid confusion with the strict definition of the word, the measurement of light. A. A. Henden and R. H. Kaitchuk, Astronomical Photometry, Van Nostrand Reinhold, New York (1982). J. L. Hopkins, Zen and the Art of Photoelectric Photometry, HPO Desktop Publishing (1990).
350
Appendix K
Color and Appearance A. Berger-Schunn, Practical Color Measurement, John Wiley & Sons, New York (1994). F. W. Billmeyer and M. Salzman, Principles of Color Technology, WileyInterscience, New York (1981). R. W. Burnham, R. M. Hanes, and C. J. Bartleson, Color: A Guide to the Basic Facts and Concepts, John Wiley & Sons, New York (1963). G. J. Chamberlin and D. G. Chamberlin, Colour: Its Measurement, Computation and Application, Heyden & Sons, London (1980). Committee on Colorimetry, The Science of Color, OSA, Crowell (1953). A second edition is due any day now! R. M. Evans, An Introduction to Color, John Wiley & Sons, New York (1948). B. Fortner and T. E. Meyer, Number by Colors, Springer-Verlag, New York (1997). F. C. Grum, and C.J. Bartelson, Optical Radiation Measurements II: Color Measurement, Academic Press, New York (1981). A. C. Hardy, Handbook of Colorimetry, MIT Press, Cambridge (1936). R. S. Hunter, The Measurement of Appearance, John Wiley & Sons, New York (1987). G. Kortüm, Kolorimetrie, Photometrie und Spektrometrie, Springer-Verlag, Berlin (1962). D. B. Judd, Contributions to Color Science, D. L. MacAdam, Ed., NBS Special Publication SP-545 (1979). A collection of the significant papers by Judd, the Deane of colorimetry! D. B. Judd and G. Wysczecki, Color in Business, Science and Industry, John Wiley & Sons, New York (1975). W. D. Wright, The Measurement of Colour, Macmillan, New York (1969). G. Wyszecki, and W. S. Stiles, Color Science, John Wiley & Sons, New York (1967); 2nd revised Ed. John Wiley & Sons, New York (1982). This classic has been reprinted in a low-cost paperback format by John Wiley & Sons, New York (2000). A must!
Radiometric Properties of Materials H. H. Blau and H. Fischer, Radiative Transfer from Solid Materials, Macmillan, New York (1962). C. Burgess and K. D. Mielenz, Advances in Standards and Methodology in Spectrophotometry, Elsevier, New York (1987). F. J. Clauss, Material Effects in Spacecraft Thermal Control, John Wiley & Sons, New York (1960).
Radiometry and Photometry Bibliography
351
G. G. Gubareff, J. E. Janssen, and R. H. Torberg, Thermal Radiation Properties Survey, Honeywell, Minneapolis (1960). B. Hapke, Theory of Reflectance and Emittance Spectroscopy, Cambridge Univ. Press (1993). J. Kamler, Luminescent Screens: Photometry and Colorimetry, Illife, London (1969). S. Katzoff, Ed., Symposium on Thermal Radiation of Solids, NASA SP-55 (1965). T. G. Kyle, Atmospheric Transmission, Emission and Scattering, Pergamon, Oxford (1991). E. P. Lavin, Specular Reflection, Elsevier, New York (1971). R. Mavrodinuenu, J. I. Schultz, and O. Menis, Accuracy in Spectrophotometry and Luminescence Measurements, NBS Special Publication 378 (1973). K. D. Mielenz, Ed., Optical Radiation Measurements III: Measurement of Photoluminescence, Academic Press, New York (1982). J. C. Richmond, Ed., Measurement of Thermal Radiation Properties of Solids, NASA SP-31 (1963). G. H. Schenk, Absorption of Light and Ultraviolet Radiation: Fluorescence and Phosphorescence Emission, Allyn & Bacon, Boston (1973). J. C. Stover, Optical Scattering: Measurement and Analysis, SPIE Press, Bellingham, Washington (1995). R. Tilley, Colour and the Optical Properties of Materials, John Wiley & Sons, New York (2000).
Spectroscopy R. B. Barnes, R. C. Gore, U. Liddel, and V. Z. Williams, Infrared Spectroscopy: Industrial Applications and Bibliography, Reinhold, New York (1944). W. R. Brode, Chemical Spectroscopy, John Wiley & Sons, New York (1943). J. R. Edisbury, Practical Hints on Absorption Spectrometry, Plenum, New York (1967). N. J. Harrick, Internal Reflection Spectroscopy, Harrick Scientific, Ossining, New York (1967). G. R. Harrison, R. C. Lord, and J. R. Loofbourow, Practical Spectroscopy, Prentice-Hall, New Jersey (1948). J. F. James and R. S. Sternburg, The Design of Optical Spectrometers, Chapman & Hall, London (1969). G. Kortüm, Reflectance Spectroscopy, Springer-Verlag, Berlin (1969). J. R. Lakowicz, Principles of Fluorescence Spectroscopy, Plenum, New York (1983). G. F. Lothian, Absorption Spectrophotometry, Hilger & Watts, London (1958).
352
Appendix K
E. J. Meehan, Optical Methods of Analysis, Interscience, New York (1964). R. A. Sawyer, Experimental Spectroscopy, Prentice-Hall, New Jersey (1951). Stearns, E. I., The Practice of Absorption Spectrophotometry, John Wiley & Sons, New York (1969). J. E. Stewart, Infrared Spectroscopy, Marcel Dekker, New York (1970). W. W. Wendlandt and H. G. Hecht, Reflectance Spectroscopy, Interscience, New York (1966). J. Workman and A. Springsteen, Applied Spectroscopy: A Compact Reference for Practitioners, Academic Press, New York (1998).
Laser Power and Energy H. G. Heard, Laser Parameter Measurements Handbook, John Wiley & Sons, New York (1968).
Temperature D. P. DeWitt and G. D. Nutter, Theory and Practice of Radiation Thermometry, John Wiley & Sons, New York (1988). H. Kaplan, Practical Applications of Infrared Thermal Sensing and Imaging Equipment, SPIE Press, Bellingham, Washington (1999). J. M. Lloyd, Thermal Imaging Systems, Plenum, NewYork (1975). T. Quinn, Temperature, 2nd Ed., Academic Press (1990). J. C. Richmond and D. P. Dewitt, Eds., Applications of Radiation Thermometry, ASTM (1985). W. P. Wood and J. M. Cork, Pyrometry, McGraw-Hill, New York (1941).
Radiometric Standards and Calibration F. Hengtsberger, Absolute Radiometry, Academic Press, New York (1989). Broad coverage with emphasis on room-temperature electrically calibrated thermal radiometers. C. L. Wyatt, Radiometric Calibration: Theory and Methods, Academic Press, New York (1978). Good, fairly thorough treatment, somewhat slanted towards the author’s (Palmer) specialty, which is far-infrared cryogenic radiometry.
Compilations A. J. Drummond, Ed., Precision Radiometry, Vol. 14 in Advances in Geophysics, Academic Press, New York (1970). H. K. Hammond III and H. L. Mason, Selected NBS Papers on Radiometry and Photometry, in Precision Measurement and Calibration, NBS Special Publication 300, Vol. 7 (1971).
Radiometry and Photometry Bibliography
353
R. B. Johnson and W. L. Wolfe, Selected Papers on Infrared Design, 2 vols. SPIE Press, Bellingham, Washington (1985). I. Nimeroff, Selected NBS Papers on Colorimetry, in Precision Measurement and Calibration, NBS Special Publication 300, Vol. 9 (1972). I. J. Spiro, Ed., Selected Papers on Radiometry, SPIE Press, Bellingham, Washington (1990).
Optical Design R. E. Fischer and B. Tadic-Galeb, Optical System Design, McGraw-Hill, New York (2000). R. Kingslake, Lens Design Fundamentals, Academic Press, New York (1978). R. Kingslake, Optical System Design, Academic Press, New York (1983). P. Mouroulis and J. Macdonald, Geometrical Optics and Optical Design, Oxford Univ. Press, New York (1997). D. C. O’Shea, Elements of Modern Optical Design, John Wiley & Sons, New York (1985). R. R. Shannon, The Art and Science of Optical Design, Cambridge Univ. Press, New York (1997). Bob was my (Palmer) professor for optical design. G. H. Smith, Practical Computer-Aided Lens Design, Willmann-Bell, Richmond, Virginia (1998). W. J. Smith, Modern Optical Engineering, 3rd Ed., McGraw-Hill, New York (2000).
Miscellaneous P. C. D. Hobbs, Building Electro-Optical Systems: Making It All Work, John Wiley & Sons, New York (2000). This publication is a pretty useful book. C. A. Poynton, A Technical Introduction to Digital Video, John Wiley & Sons, New York (1996).
Technical Organizations in Radiometry and Photometry CIE
The Commission Internationale de L’Eclairage (CIE) has numerous technical committee reports that are relevant. Contact Thomas Lemons, TLA-Lighting Consultants Inc., 7 Pond St., Salem, MA 01970, Tel: (508) 745-6870, Fax: (508) 741-4420, for a listing of current publications and pricing. Check into their web page (www.cie.co.at) for more information. Some pertinent reports, primarily from Division 2, are listed in Appendix H.
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Appendix K
CORM
The Council for Optical Radiation Measurements (CORM) was founded over twenty years ago to promote optical radiation measurement science and engineering and foster cooperation among the many government agencies, industrial firms, and universities, and to formulate and transmit national needs to NIST. They meet annually in May and publish Optical Radiation News biannually. Contact: CORM Treasurer, 1043 Grand Ave. #312, St. Paul, Minnesota 55105 (www.corm.org). CORM documents are listed in Appendix H. NEWRAD
The NEWRAD conference series is an outgrowth of a meeting organized by Peter Foukal and the papers were published by Cambridge University Press, Massachusetts, in 1985. The proceedings of the first meeting were a private publication. The second meeting took place at the National Physical Laboratory in London in 1988, and the proceedings were published as New Developments and Applications in Radiometry, N. Fox and D. Nettleton, Eds., by IOP Publishing, London (1989). The next four meetings were held in Davos (1990), Baltimore (1992), Berlin (1995) and Tucson (1997). The proceedings of these meetings were published as special issues of Metrologia (Elsevier), Volumes 28(3), 30(4), 32(6), and 35(4), respectively. The seventh conference was held October 25–27, 1999, in Madrid. Check out http://newrad.metrologia.csic.es. NIST
The U.S. National Institute of Science and Technology (NIST, formerly National Bureau of Standards, NBS) has a number of valuable special publications that describe their calibration services and procedures. Appropriate ones include the following. They may be purchased from NTIS.
NBS Measurement Services: Spectral Radiance Calibrations, J. H. Walker, R. D. Saunders, and A. T. Hattenburg, NBS, Spec. Publ. 250-1 (1987). NBS Measurement Services: Far Ultraviolet Detector Standards, L. R. Canfield and N. Swanson, NBS, Spec. Publ. 250-2 (1987). NBS Measurement Services: Radiometric Standards in the Vacuum Ultraviolet, J. Z. Klose, J. M. Bridges, and W. R. Ott, NBS, Spec. Publ. 250-3 (1987). NBS Measurement Services: Regular Spectral Transmittance, K. L. Eckerle, J. J. Hsia, K. D. Mielenz, and V. R. Weidner, NBS, Spec. Publ. 250-6 (1987). NIST Measurement Services: Spectral Reflectance, P. Y. Barnes, E. A. Early, and A. C. Parr, NIST Spec. Publ. 250-8 (1987, revised 1997). Photodetector Spectral Response Calibration Transfer Program, E. F. Zalewski, NBS, Spec. Publ. 250-17, 45 (1988). NIST Measurement Services: Photometric Calibrations, Y. Ohno, NIST, Spec. Publ. 250-37 (1997).
Radiometry and Photometry Bibliography
355
NIST Measurement Services: Radiance Temperature Calibrations, NIST, Spec. Publ. 250-43 (1997). NBS Measurement Services: Spectral Irradiance Calibrations, J. H. Walker, R. D. Saunders, J. K. Jackson, and D. A. McSparron, NBS, Spec. Publ. 250-20 (1987). NIST Measurement Services: Spectroradiometric Detector Measurements: Parts I and II—Ultraviolet and Visible to Near Infrared Detectors, T. C. Larason, S. S. Bruce, and A. C. Parr, NIST, Spec. Publ. 250-41, (1998). NIST Measurement Services: Spectroradiometric Detector Measurements: Part III—Infrared Detectors, A. L. Migdall and G. Eppeldauer, NIST, Spec. Publ. 250-42, (1998). SPIE
Proceedings of SPIE are published unrefereed papers as presented at conferences of SPIE. Several conferences and resulting proceedings have been devoted to radiometry, photometry, and closely allied topics. These Proceedings volumes are available on SPIE’s digital library: http://spiedigitallibrary.org. They include: 196 499 888 1109 2161 2815 7298 7299 7300
Measurements of Optical Radiations (1979) Optical Radiation Measurements I (1984) Laser Beam Radiometry (1988) Optical Radiation Measurements II (1989) Photometry (1993) Optical Radiation Measurements III (1996) Infrared Technology and Applications XXXV (2009) Thermosense XXXI (2009) Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XX (2009) 7410 Optical Modeling and Measurements for Solar Energy Systems III (2009) 7419A Infrared Detectors and Focal Plane Arrays X (2009)
Open Literature Numerous archival and trade journals also offer significant papers on radiometry and detection of optical radiation. They include:
Applied Optics (OSA) IEEE Transactions on Electron Devices (IEEE) Infrared Physics and Technology (Elsevier) Journal of the Optical Society of America A (OSA)
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Journal of Scientific Instruments (IOP) Laser Focus World (PennWell Corp.) Lightwave Technology (IEEE) Optical Engineering (SPIE) Photonics Spectra (free) Review of Scientific Instruments (AIP)
Publications Available on the Internet All you ever wanted to know about the SI is contained at BIPM (www.bipm.fr) and at NIST (physics.nist.gov/cuu/). Available publications (highly recommended) include:
The International System of Units (SI) 7th Ed. (1998), direct from BIPM. The official document is in French; the English translation is available in PDF format. NIST Special Publication SP330, “The International System of Units (SI).” The U.S. edition of the above BIPM publication. Available in PDF format. NIST Special Publication SP811, “Guide for the Use of the International System of Units (SI).” Available in PDF format. Papers published in NIST Journal of Research since 1995 are also available on the web in PDF format.
Appendix L
Reference List for Noise and Postdetection Signal Processing Supplied by L. Stephen Bell May 7, 2009
Books and articles D. P. Blair and P. H. Sydenham, “Phase sensitive detection as a means to recover signals buried in noise,” J. Phys. E: Sci. Instrum. 8, p. 621 (1975). E. R. Davies, Electronics, Noise and Signal Recovery, Academic Press, London (1993). A. De Sa, Principles of Electronic Instrumentation, Arnold, London (1981). See Chapter 10, “Principles of signal recovery.” H. Doherty, “Techniques of low level light measurement,” Lasers & Applications, pp. 41–45, July (1983). P. J. Fish, Electronic Noise and Low-Noise Design, McGraw-Hill, New York (1994). J. Graeme, Photodiode Amplifiers, McGraw-Hill, New York (1995). Fundamentals of photodetection circuits. Good coverage of noise-reduction techniques for circuits and discusses effects from power supplies and external sources. P. Horowitz and W. Hill, The Art of Electronics, 2nd Ed., Cambridge, New York (1989). One of the best single books on electronics. Look in Chapter 7 on “Precision Circuits and Low-noise Techniques” and Chapter 15 on “Measurements and Signal Processing,” which has sections on reducing bandwidth and spectral analysis. G. Lawday, D. Relann, and G. Edlund, A Signal Integrity Engineer’s Companion, Prentice Hall, New Jersey (2008). Real-time test and measurement and designsimulation techniques to systematically eliminate signal integrity problems. 357
358
Appendix L
M. L. Meade, “Advances in lock-in amplifiers,” J. Phys. E: Sci. Instrum. 15, p. 395 (1982). C. D. Motchenbacher and J. A. Connelly, Low-Noise Electronic System Design, John Wiley & Sons, New York (1993). D. M. Munroe, “Signal-to-noise ratio improvement,” Chapter 11 in Handbook of Measurement Science, Vol. 1, P. H. Sydenham, Ed., John Wiley & Sons, New York (1982). Includes sections on noise and noise bandwidth, signals and SNR, preamp selection, grounding and shielding, bandwidth reduction, lock-in amplifiers, signal averaging, correlation, and photon counting. H. W. Ott, Noise Reduction Techniques in Electronic Systems, 2nd Ed., John Wiley & Sons, New York (1988). R. A. Pease, Ed., Analog Circuits-World Class Designs, Elsevier, Burlington Massachusetts (2008). A top-notch, thorough coverage of analog amplifiers, filters, and analog-to-digital converters. The filter sections cover low pass, high pass, and bandpass, along with the operational amplifier requirements to make the filters meet their desired specifications. R. G. Lyons, Understanding Digital Signal Processing, Prentice Hall, New Jersey (2004). This is another easy-to-understand introduction to DSP. D. C. Smith, High Frequency Measurements and Noise in Electronic Circuits, Kluwer Academic Publishers, New York (1993). J. Williams, Ed., Analog Circuit Design—Art, Science, and Personalities, Butterworth-Heineman, Newton, Massachusetts (1991). Per reviewer Phil Hobbs: “Design ... is an art; there’s always more than one way to do it, and the individuality of the designer has a strong influence on the way the design turns out: hence Art, Science, and Personalities. What it means is that for designs that are not routine, the designer’s personality has a lot to do with how it comes out.” I recommend this book to anyone who wants to become a better analogue designer and is not easily put off by whimsy in technical writing. J. Williams, Ed., The Art and Science of Analog Circuit Design, ButterworthHeineman, Woburn, Massachusetts (1998). This is Jim William’s second book. Per reviewer Phil Hobbs: “The emphasis of this volume is growing good analog engineers, by teaching the rhythm of the insight, design, prototype, debug iteration as practiced by the best. If you have circuits to design, this book will pay for itself in about 5 minutes, and you’ll be a more confident and adventurous designer.” T. H. Wilmshurst, Signal Recovery from Noise in Electronic Instrumentation, 2nd Ed., Adam Hilger, Bristol (1990).
Reference List for Noise and Postdetection Signal Processing
359
Software and Commentary, Downloadable Resources, and E-books Numerical Recipes: The Art of Scientific Computing, 3rd Ed., Cambridge Univ. Press, New York (2007). The book includes commented full listings of more than 400 unique C++ routines that can be downloaded in machine-readable form for inclusion in users’ programs. Information is available from www.nr.com. Matlab® software has extension packs (“toolkits”) for signal processing, image processing, and wavelets. It is available from www.mathsoft.com. Academic and student versions are available for discounted pricing. R. Pratap, “Getting Started with Matlab® 7,” A quick introduction for scientists and engineers, Oxford Univ. Press, New York (2006). V. Ingle and J. Proakis, Digital Signal Processing Using Matlab®, 2nd Ed., CLEngineering (2007). This book is part of a large library of Matlab® information via: http://engineering.thomsonlearning.com. ISBN-13: 978-0495-07311-6. This is the big list of books for Matlab® signal processing: http://www.mathworks.com/support/books/index_by_categorytitle.html?category =11&sortby=title The main Matlab® repository of contributed code is found at: http://www.mathworks.com/ matlabcentral. Wavelab is a software library of Matlab® routines for wavelet and other signal analyses. The library is available free of charge over the Internet from Stanford University: http://www-stat.stanford.edu/~wavelab/. MathCad® software has extension packs (“toolkits”) for signal processing, image processing, and wavelets. It is available from: PTC (formerly Mathworks): http://www.ptc.com/products/mathcad/. Academic and student versions are available for discounted pricing. Mathematica® software also has capabilities for signal processing, image processing, and wavelets via its “Wavelet Explorer.” It is available from www.wolfram.com. Academic (discounted) versions are available. Stéphane Mallat, A Wavelet Tour of Signal Processing, Academic Press, New York (1999). Information is available from the site: http://www.cmap. polytechnique.fr/~mallat/book.html. This is the wavelet toolbox called “LastWave,” which is written in the “C” language. Available from http://www.cmap.polytechnique.fr/~bacry/LastWave. http://www.amara.com/current/wavesoft.html This site also includes links to wavelet code for use with Mathematica®. FFTW is a “C” subroutine library for computing the discrete Fourier transform (DFT) in one or more dimensions, of arbitrary input size, and of both real and complex data (as well as of even/odd data, i.e. the discrete cosine/sine
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Appendix L
transforms or DCT/DST). FFTW is free (source code in “C”) software available from: www.fftw.org. S. Smith, The Scientist and Engineer’s Guide to Digital Signal Processing, California Technical Pub. (1997). Available as a book and freely distributed over the internet in electronic form: http://www.dspguide.com/ Other online resources for signal processing and/or FFT-related questions are available from http://www.dsprelated.com/ and from Usenet: comp.dsp (digital signal processing), sci.math.num-analysis (numerical analysis and scientific computing). R Project for Statistical Computing. This is free GNU-licensed software from http://www.r-project.org. This website provides a peer-reviewed encyclopedia for many topics in science: http://www.scholarpedia.org/. A specific discussion on the phenomena of stochastic resonance regarding SNR is available from http://www.scholarpedia.org/article/Stochastic_resonance. D. L. Instruments (Ithaco) App Note IAN-102, “Measuring noise spectra with variable electronic filters,” Available from the website: http://www.dlinstruments.com/. 233 Cecil A. Malone Drive, Ithaca, New York 14850. The site has many other “Technotes” on use of lock-in amplifiers.
Index background, 6, 96 test chambers, 259 baffles, 227 bandpass filter, 301 simple, 303 bandwidth shrinkage factor, 300 barrier height, 187 basic radiance, 25 radiometer, 221 Bayer algorithm, 207 bias voltage, 157 bidirectional reflectance distribution function, 65, 73, 317 bidirectional transmittance distribution function, 63, 73 blackbody, 77, 121 curve, 86 equation, 100 radiation, 87, 95, 138 simulator, 33, 83, 132, 226, 242, 255, 261 source, 49 spectral radiance, 88 BLIP, 133 blooming, 204 Bode plot, 129 bolometer, 155, 157 Boltzmann’s constant, 85, 178, 181, 189, 313 Bouguer, 4, 30 Butterworth RC filters, 297
1/f, 139 1/f noise, 143, 145, 157, 196, 226, 245, 246, 304 2D array, 216 3-dB bandwidth, 136 3-dB frequency, 130 absorptance, 69, 72, 77, 98 spectral, 69 absorption, 6, 61, 69, 79, 104, 314 absorption coefficient, 71 accuracy, 242, 243 acousto-optical tunable filters, 239 active sources, 6 additive dispersion, 235 air mass, 119 airglow, 121 aliasing, 218 Allan variance, 245 Amici, 231 amorphous silicon, 199 amplifier noise, 143 angle of observation, 32 aperture stop, 23, 24, 40, 41, 218, 220 apparent radiance, 51, 52 area array, 199 array 2D, 127 detector, 175 imagers, 199 atmosphere, 6, 28, 104, 235, 314 atmospheric transmission, 51 loss, 49 aurora, 121
calibrate, 247 a radiometer, 309 361
362
calibration, 102, 253, 256 configurations, 241, 256, 257 philosophy, 257 camera equation, 54, 57 carbon arc, 109 carrier lifetime, 170, 172 CCD, 89, 193 noise, 142 central obscuration, 57, 260 charge injection device, 204, 208, 211 charge-coupled device, 203, 204, 208, 211 charge-transfer efficiency, 142, 203 Chauvenet criteria, 247 chief ray, 23 chopper, 109, 218, 225, 235 reflecting, 224 circular variable filter, 236 classical variance, 245 collimators, 259 color films, 201 compact fluorescent lamp, 107, 116, 123 complementary metal-oxide semiconductor, 207 conduction band, 164, 177 cone half angle, 16, 18, 41 configuration factor, 38 cosine3 law, 31, 32, 33, 58 cosine4 law, 33–35 Crooke radiometer, 163 cross-sectional area, 20 Curie temperature, 158, 160 current responsivity, 195 cutoff frequency, 130 wavelength, 128, 177 Czerny-Turner, 232
D*, 132, 150, 154, 162, 174, 197 photon, 133 D**, 133 D*BLIP, 174, 197
Index
dark current, 181, 191 detection, 5 detective quantum efficiency, 131 detectivity, 132 detector, 7 array, 236 D*, 264 field of view, 55 noise-equivalent power, 264 silicon, 128 thermal, 128 dielectrics, 102, 123 sources, 108 diffuse, 61, 227 materials, 317 reflector, 75 surface, 65, 73, 316 diffusers, 224 dimensional analysis, 17 direct-method approach, 262 distant extended source configuration, 260 distant small source configuration, 258 Doppler Gaussian, 110 effect, 111 dynamic resistance, 196 earth projected area, 51 radiance, 122 reflectance, 51 effective focal length, 19 effective noise bandwidth, 136, 137, 174, 218, 297 Einstein diffusion constants, 190 electrical resistance, 152 time constant, 159 electroluminescent sources, 117 electron-hole pairs, 195 electro-optical instrument calibration, 257
Index
system, 263, 299 emission, 6, 76, 83, 104, 314 emissivity, 76 emittance, 76, 98 spectral, 76, 78 emitter, 18 energy gap, 164, 166, 167 entrance pupil, 19, 23, 24, 54, 218, 222, 263, 266 entrance slit, 22 equation of radiative transfer, 36 basic form, 58 differential form, 46 integral form, 36 error, 241, 244 assessment, 256 étendue, 20, 229, 263 exhaust gases, 110 exit pupil, 23, 24, 54, 218 extended source, 34, 222, 223, 264 extrinsic photoconductor, 169 semiconductor, 167 eye damage, 123
f/#, 19, 21, 22, 35, 264 system parameter, 53 Fabry-Perot, 237, 238 Fastie Ebert, 232 Fermi level, 176 field of view, 6, 220, 222, 251, 263 instantaneous, 217, 318 of the detector, 55 field stop, 23, 24, 218, 220, 258 filters, 236 flat-plate solar collectors, 55 FLIR devices, 315 fluorescent lamp, 115 flux density, 11 Foote’s formula, 35 forward-looking infrared, 209, 318 devices, 315 Fourier transform infrared spectrometer, 237
363
frame transfer, 206 architecture, 205 free spectral range, 230, 237, 239 frequency, 134 Fresnel equation, 103 reflection losses, 71 full frame, 205 architecture, 204 gain of power, 41 gases, 103, 123 Gaussian, 110, 111, 112, 137, 139 distribution, 147, 244 noise, 135 GE radiation calculator, 100 generation, 5 generation-recombination noise, 141, 143, 173, 197 geometrical extent, 20 glint, 319 Golay cell, 163 half-power point, 298 Havens limit, 150 H-D curve, 202 heat capacity, 141, 147 hybrid architecture, 208 illegitimate errors, 248 illuminance, 8, 57 illumination engineering, 38 image irradiance, 55 impedance, 131 incandescent light bulbs, 107 incoherent radiation, 250 sources, 119 index of refraction, 12, 79 infrared, 2 photodetector array, 209 sources, 110
364
Infrared Handbook, The 76, 78, 226 instantaneous field of view, 217, 318 integrating sphere, 5, 46, 47, 224, 261 intensity, 31, 40, 48, 266 interferometer, 237, 238 interline transfer, 206 architecture, 205 International Bureau of Weights and Measures, 254 intrinsic photoconductor, 169 semiconductor, 164 invariance of throughput, 21 invariant, 20 inverse square law, 37, 45, 48, 258 of irradiance, 17, 30 inversion layer, 198 irradiance, 25, 28, 30, 31, 121, 201, 267, 316 at the detector, 42, 48 inverse square, law of, 17, 30 on the detector, 43, 171 reduction in, 57 responsivity, 129 isotropic source, 58 I-V curve, 191, 194 I-V equation, 189 Johnson noise, 137, 143, 152, 157, 162, 173, 182, 196 Jones method, 262 Jones, R. Clark, 262, 309 Kirchhoff, 4 law, 77, 98, 99, 149, 314 KTC reset noise, 143
Lambert, 4 Lambert-Bouguer-Beer law, 70
Index
Lambertian, 27, 37 approximation, 33, 37, 316 disc, on-axis, 43 disc radiance, 42 source, 32, 310 sphere, 44 sphere, on-axis, 45 Langley, S. P., 155 large-area blackbody radiation simulator, 261 imaging array, 203 laser, 118, 262 laser-power meter, 262 least-significant bit, 143 lens transmission, 41 light-emitting diode (LED), 83, 105, 117 linear array, 216 photodiode array, 203 linearity, 131, 247 Littrow, 231, 234 long-wave infrared, 209 Lorentzian, 110, 112, 113 lossless medium, 44 optical system, 42 LOWTRAN7, 314 lumens, 8 luminance, 8 luminescence, 69, 110 luminescent sources, 83 Lyot stop, 228 magnification, 54, 57 majority carriers, 187 Marcel Golay, 236 marginal ray, 24 matte reflectors, 58 maximum power transfer theorem, 156 of electrical engineering, 172
Index
mean earth–sun distance, 50 square noise voltage, 135, 137 measurement, 4 measurement equation, 250 metallic sources, 108 metals, 102, 123, 156, 176 Michelson, 237 microchannel plates, 184 microphonic, 162 noise, 142 Mie scatter, 119 minority carriers, 187 concentrations, 190 model validity, 248 modulation transfer function, 202 moments normalization, 307 monochromator, 218, 229, 231, 234 moon and sun angular subtense, 51 multiple reflections, 47 muzzle flash, 110 narrowband measurements, 217 national standard, 255 near infrared, 209 near-extended-source, 55 configuration, 261 near-small-source calibration, 262 negative electron affinity material, 180 Nernst glower, 108 Nicodemus, 66 noise, 131, 134, 243 1/f, 139, 143, 145, 157, 196, 226, 245, 246, 304 amplifier, 143 bandwidth, 132, 149 CCD, 142 factor, 143, 184 Gaussian, 135 generation-recombination, 141, 142, 143, 173, 197
365
Johnson, 137, 143, 157, 162, 173, 182, 196 microphonic, 142 power, 298 quantization, 143, 246 shot, 139, 182, 196 temperature, 144 fluctuation, 141 thermal, 135 thermal fluctuation, 162 triboelectric, 142 white, 135, 146, 246, 303 noise-equivalent flux density, 252 irradiance, 216, 252, 265 photon flux, 132 power, 154, 252 temperature difference, 210, 216 normal distribution, 245 incidence, 35, 103 numerical aperture, 19 object at infinity, 53 off-axis collimator, 260 Ohm’s law, 136, 138, 173 OLEDs, 117 optical axis, 24, 36 element, 19 radiant power, 128 radiation, 73 detectors, 127 system, 21, 23, 48 systems, 16, 19 thickness, 71, 72 transmission, 265 organic light-emitting diodes. See OLEDs overlapping of orders, 230
366
passive sources, 6 Pauli exclusion principle, 176 PCTRAN, 314 Peltier coefficient, 151 effect, 152 phosphors, 115 photocathode, 181, 185 photoconductive, 7, 164 detector, 169, 171, 173, 175 gain, 172 mode, 194 photodiode, 5 photoemission, 176 photoemissive, 7, 164 photoemissive detector, 182 photoemitter, 180 photographic film, 199, 200 photometric, 2 photometry, 191, 217 photomultiplier tubes, 89, 183 photon, 128 D*, 133 detectors, 127 flux, 129 irradiance, 170 noise, 142 radiance spectral, 90 responsivity, 129 photopic response of the eye, 217 photovoltaic, 7, 164, 191 cell, 165 detector, 175, 185, 191, 192, 195, 198 solar cell, 193 physical standards, 253 Planck, 5, 84 constant, 89, 313 equation, 84, 86, 89, 91, 92, 93 expression for blackbody radiation, 84 function, 77 plane angle, 13, 16, 17 p-n junction, 185, 187
Index
point detector, 175 source, 29, 30, 31, 34, 220, 222, 252, 310 polarization, 248 sensitivity, 216 states, 70 polarized, 102, 103 polished metal surfaces, 33 power gain, 136, 298 generator, 192 responsivity, 262 spectrum, 134 precision, 243 pressure (Lorentzian), 110 primary standard, 254 principle of superposition, 37 projected area, 13, 32 solid angle, 17, 18, 19, 20, 26 projection systems, 56 pure material, 62 pyrheliometer, 221 pyroelectric coefficient, 158, 160 detector, 157, 159, 161 quantization noise, 143, 246 quantum efficiency, 176, 178, 195 quantum-well infrared photodetectors, 209 RA product, 133 radian, 13, 15 radiance, 24, 26, 27, 32, 52, 63, 314 apparent, 52 of the source, 223 responsivity, 129 spectral, 63, 87 radiant energy, 24 exitance, 25, 26, 27, 38, 44
Index
flux, 61, 63 intensity, 25 power, 24, 25, 29, 36, 39 radiation contrast, 96, 97 geometry, 30 radiative transfer, 36, 38 basic equation, 58, 263 radiometer, 21, 215, 241 optical system, 311 radiometric calibration, 17, 241 configuration, 6, 251 equation, 228 instruments, 215, 228, 250 measurements, 217 system, 252 radiometry, 1, 24, 191, 211, 223, 248 Raman scattering, 69 random errors, 243 noise, 244 uncertainty, 249 range equation, 251, 252, 266 ray, 11 Rayleigh, 84 scatter, 119 Rayleigh-Jeans, 93 equation, 84, 92 law, 92 RC bandpass filter, 300 circuit, 130 low-pass filter, 299 receiver, 18 reflectance, 47, 64, 70, 315 factor, 65, 67 spectral, 63, 78 reflecting chopper, 224 reflection, 61, 63, 83 reflective natural objects, 105 refractive collimator, 259 elements, 109
367
index, 19, 85, 231, 239 resolving power, 229, 230, 238 responsive quantum efficiency, 131, 170 responsivity, 128, 132, 157 reverse saturation current, 189, 190, 191 reverse-bias mode, 194 Richardson equation, 181, 182 right circular cone, 18 root mean square, 130 root sum square, 249 rough aluminum, 75 scattering, 6 Schottky barrier, 198 secondary standard, 254 Seebeck coefficient, 151 effect, 150 semiconductor detectors, 140 photocathodes, 177 Seya-Namioka, 234 short-wave infrared, 209 shot noise, 139, 182, 196, 244 signal processing, 7 signal-to-noise ratio, 131, 149, 217, 244, 266, 297, 303 silicon amorphous, 199 detector, 128 simple bandpass filter, 303 simple equation for transfer of radiant power, 263 single-element detectors, 127 Snell’s law, 12, 25 solar cell, 192, 198, 219 collectors flat-plate, 55 constant, 28, 50 irradiance, 49 panels, 193
368
spectrum, 121 zenith angle, 119, 314 solid angle, 15–17, 25, 66, 223 field of view, 265 source image, 21 spatial resolution, 202 specification sheet, 215 spectral absorptance, 69 absorption coefficient, 71 bandwidth, 216 directional emissivity, 98 emittance, 78, 102, 106 linewidth, 251 photon radiance, 90 radiance, 63, 87, 250, 313 blackbody, 88 radiometer, 215 reflectance, 63, 78 response, 201 of the eye, 8 responsivity, 128, 130, 250 sensitivity, 201 transmittance, 62, 251 spectrometer, 22, 217, 230, 235 spectroradiometer, 217, 228, 241 specular, 61, 227, 316 reflecting surfaces, 33 reflection, 319 reflectors, 58 surfaces, 73 speed of light, 12 sphere coatings, 47 SPRITE detector, 209 standard, 254–255 detector, 257 source, 257 statistical analysis, 243 Stefan-Boltzmann constant, 84 Stefan-Boltzmann law, 89, 95 steradian, 15 stray light, 227, 228, 260 subtractive dispersion, 235 sun projected area, 51
Index
sunglint, 313 sunlit scene, 52 surface normal, 13 reflectance, 317 systematic error, 241, 247 uncertainty, 249 systems analysis, 211 engineering, 211 target, 96 temperature coefficient of resistance, 155 temperature fluctuation noise, 141 thermal, 7, 104, 127 conductance, 141, 149 detection of optical radiation, 147 detector, 128, 141, 147, 312 emission, 313 fluctuation noise, 162 infrared, 319 noise, 135 resistance, 147, 148 time constant, 141, 148, 159 thermistors, 156 thermocouple radiation detectors, 153 thermoelectric detector, 150 effect, 150 thermopile radiation detectors, 153 three-color CCDs, 207 throughput, 20, 229, 230, 239, 263 time constant, 130, 154 total emissivity, 98 traceability, 254 transmission, 5, 61, 62, 79 loss, 40, 48, 53 of the lens, 42 of the optics, 223
Index
transmittance, 70, 72, 315 total, 62 triboelectric noise, 142 tungsten lamps, 105, 258 tungsten-filament lamp, 105–106 tungsten-halogen lamp, 106–107 Twyman-Green, 237 type A errors, 243 type B errors, 241 Ulbricht, R., 5, 46 ultraviolet, 2 detector array, 208 uncertainty, 241, 244, 253 uncooled thermal-imaging devices, 210 uniform radiance source, 47 unit solid angle, 17 unpolarized light, 70
369
valence band, 168, 177 vector, 11 vignette, 41 vignetting, 57 visible, 2 voltage responsivity, 160 Wadsworth, 231, 234 wavefront, 11 Welsbach mantle, 109 white diffuse panel, 261 noise, 134, 135, 146, 246, 297, 303 Wien, 84, 93 approximation, 93, 97 displacement law, 86 work function, 176 working standard, 254 Zener effect, 194 Zodiacal light, 121
James M. Palmer (1937-2007) was a research professor emeritus in the College of Optical Sciences, University of Arizona. He received his AB in physics from Grinnell College in 1959, and his MS and PhD degrees in optical sciences in 1973 and 1975, respectively, from the University of Arizona, specializing in radiometry and infrared systems. Prior to attending the University of Arizona, he worked in industrial positions at Hoffman Electronics Corporation and Centralab, Semiconductor Division of Globe Union, Inc. Over a career spanning more than 40 years, he authored or coauthored more than 60 technical papers on many aspects of radiometry and photometry, and he was named Fellow of SPIE in 2003. Other awards include a NASA Group Achievement award for his work on the Pioneer Venus Mission (1979), a Tau Beta Pi Teacher of the Year Award (1992), and a Non-Traditional Student Teaching Award from the University of Arizona (1993). He taught numerous short courses at SPIE conferences, CIE meetings, and conferences of the Optical Society of America. He served as a consultant on commercial and government projects. Dr. Palmer was a brilliant lecturer whose former students, worldwide, have expressed gratitude for the knowledge they gained under his tutelage. Barbara G. Grant received her BA in mathematics from San Jose State University in 1983, and her MS in optical sciences from the University of Arizona in 1989, where her graduate research focused on the absolute radiometric calibration of spaceborne imaging sensors. She was subsequently employed at Lockheed Missiles and Space Company, Sunnyvale, California, where supported by excellent management, she pursued problems in infrared sensor calibration and postflight data analysis of electro-optical payloads. She also worked as a NASA contractor, overseeing integration and test of imager and sounder payloads on the GOES weather satellite, for which she received two NASA awards. She is the author of two book-length volumes of market research for process spectroscopy instruments. Since 1995, her consultancy, Lines and Lights Technology, has addressed problems in systems engineering, infrared imaging and data analysis, UV measurement, and spectroradiometry, among other areas.
