introduction to radiometry and photometry, second edition 2014
TRANSCRIPT
Introduction to Radiometry and Photometry
Second Edition
William Ross McCluney
ARTECH
HOUSE BOSTON LONDON
a rte c h house. corn
Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the U.S. Library of Congress.
British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library.
Cover design by John Gomes
ISBN 13: 978-1-60807-833-2
© 2014 ARTECH HOUSE 685 Canton Street Norwood, MA 02062
All rights reserved. Printed and bound in the United States of America. No part of this book may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permission in writing from the publisher.
All terms mentioned in this book that are known to be trademarks or service marks have been appropriately capitalized. Artech House cannot attest to the accuracy of this information. Use of a term in this book should not be regarded as affecting the validity of any trademark or service mark.
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Contents
Introduction xiii
End Notes xviii
Acknowledgments xxi
1 Fundamental Concepts of Radiometry 1
1.1 Electromagnetic Radiation 1
1.2 Terminology Conventions 4
1.3 Wavelength Notations and Solid Angle 4
1.4 Fundamental Definitions 7
1.5 Lambertian Radiators and Lambert's Cosine Jaw 13
1.6 Radiance, Irradiance, Intensity, and Flux Relationships 16
1.7 Connection with Electromagnetic Theory 20
1.8 Polarization 22
1.9 Photon Flux 25
1.10 Radiometric Information 28
End Notes 36
V
Vi Introduction to Radiometry and Photometry
2 Fundamental Concepts of Photometry 39
2.1 Light 39
2.2 Photometric Definitions 43
2.2.1 Radiation Luminous Efficacy, K and the V-lambda
Function 47-
2.2.2 Lighting System Luminous Efficacy, K 50
2.3 Luminance and Brightness 51
2.4 Luminance and Vision 54
2.5 Disability Glare 57
2.6 Discomfort Glare 59
2.7 Illumination 60
2.7.1 Illuminance Selection 62
End Notes 68
3
Blackbodies and Other Sources 11
3.1
Blackbody Radiation 71
3.2
Planck's Law 73
3.3
Wien Displacement Law 77
3.4
Luminous Efficacy of Blackbody Radiation 78
3.5
Color and Distribution Temperatures
79
3.6
Emission Into an Imperfect Vacuum 81
3.7
Radiation Exchange 81
3.8
Experimental Approximation of a Blackbody 82
3.9
Other Real Sources 83
End Notes .10
96
4
Source/Receiver Flux Transfer Calculations
99
4.1
Introduction 99
Contents VII
4.2 Geometry and Definitions 100
4.2.1 Case 1 102 4.2.2 Case 2 104 4.2.3 Case 3 104 4.2.4 Case 4 105 4.2.5 Case 5 108 4.2.6 Case 6 109 4.2.7 Case 110
4.3 Configuration Factor 111
4.4 Net Exchange of Radiation 113
4.5 Summary 114
End Notes 125
5 The Invariance of Radiance and the Limits of Optical Concentration 127
5.1 Introduction 127
5.2 Radiance Is a Field Quantity 128
5.3 Pencils of Rays 128
5.4 Elementary Beam Of Radiation 129
5.5 Radiance Invariance 131
5.6 Radiance Invariance at an Interface 132
5.7 Radiance Through a Lens 134
5.8 Radiance in Absorbing and Scattering Media 135
5.9 Concentrating Radiance Meter 136
5.10 The Limits of Optical Concentration 141
End Notes 145
6 Optical Prop ertiesof Materials 147
6.1 Introduction 147
6.2 Terminology 148
VIII Introduction to Radiometry and Photometry
6.3 Surface and Interface Optical Properties
6.3.1 Conductor Optical Properties 6.3.2 Nonconductor Optical Properties 6.3.3 Surface Emission Properties
6.3.4 Angular Dependence of Dielectric Optical Properties
6.3.5 Rough Surfaces
6.4 Bulk Medium Optical Properties
6.5 Properties of Plane Parallel Plates
6.5.1 Nonscattering Media 6.5.2 Scattering Media
6.6 Angular Dependence
6.7 Broadband Angle Properties
6.7.1 Transmittance and Reflectance Equations
6.7.2 Specular and Diffuse Optical Properties
6.8 Spectral Dependence
6.9 Broadband Spectral Properties
6.10 Spectral Selectivity
End Notes
1 The Detection of Radiation 201
7.1 Introduction 201
7.2 Basic Concepts 202
7.3 Classification of Detectors 208
7.3.1 Thermal Detectors 208
7.3.2 Photemissive Detectors 213
7.3.3 Semiconductor Devices 218
7.3.4 Multielement Detectors, Charge Transfer Devices, and Imagers 227
7.4 Detector Noise 231
7.5 Signal Modulation and Radiation Chopping 234
7.6 Characterization of Detector Performance 237
7.6.1 Responsivity, R 238
Contents
ix
7.6.2 Quantum Efficiency, 71 238 7.6.3 Noise Equivalent Power, NEP 239 7.6.4 Detectivity, D 240 7.6.5 Photon Noise-Limited Performance 240
7.7 Flux Conditoning Prior to the Detector 242
7.7.1 Cosine Response Correction 242 7.7.2 Photopic Correction 245 7.7.3 Spectral Filtering 246
7.8 Signal Conditioning Affer the Detector 249
7.9 Detector Calibration 249
7.10 Example Detectors and Their Characteristics 251
End Notes 259
8 Optical Systems 263
8.1 Introduction 263
8.2 Optical Axis 264
8.3 Idealized (Thin) Lens Theory 265
8.4 Radiance and Irradiance of Images 270
8.5 Vignetting 273
8.6 Aberrations 273
8.6.1 Spherical Aberration 273 8.6.2 Chromatic Aberration 276 8.6.3 Distortion 277 8.6.4 Coma 277 8.6.5 Astigmatism 278 8.6.6 Field Curvature 279 8.6.7 Correctiug Aberrations 280 8.6.8 The Diffraction Limit 280
8.7 Image Quality 282
8.8 Flux Distribution 283
8.9 Nonimaging Optical Systems 285
x Introduction to Radiometry and Photometry
8.10 Throughput 287
8.11 Integrating Spheres 289
8.11.1 Cosine Correction 292
8.11.2 Transmissometers and Reflectometers 293
8.12 Monochromators 297
8.12.1 Spectral Filters 297
8.12.2 Scanning Monochromators 304
8.13 Windows 310
8.14 Sources 311
8.15 Goniometers 312
8.16 Transmissometers/Reflectometers 313
8.17 Scattering Meters, Nephelometers, Turbidimeters, and Haze Meters 313
End Notes 320
9 Radiometers and Photometers 325
9.1 Introduction 325
9.2 General Design Factors 327
9.3 Broadband Irradiance and Radiance Meters 329
9.4 Restricted Spectral Band Irradiance Meters for the Ultraviolet through the Infrared 333
9.5 Illuminance and Luminance Meters 333
9.6 Spectro radiometers 334
9.7 Calibration of Radiometers and Photometers 338
9.7.1 Transfer Standards 340
9.7.2 Broadband Irradiance Standard Sources 343
9.7.3 Standard Sources for Spectral'Irradiance and Spectral Radiance 344
9.7.4 Absolute Radiometry 346
9.7.5 Standard Illuminance and Luminance Sources 351
Contents Xi
9.7.6 Radiometer/Photometer Calibration Using Standard Sources 351
9.7.7 Spectroradiometer Calibration 352 9.7.8 National Standards Laboratories and Other, Labs
and Instrument Organizations 353
End Notes 355
10 Metric Primer and Additional Radiometric and Photometric Quantities and Units 359
10.1 Introduction ' " 359
10.2 The SI System of Units 360
10.2.1 Basic Metric Principles 360 10.2.2 Metric Units for Radiometry and Photometry 363
10.3 The I-P System of Units 364
10.4 Photon Flux Units 364
10.5 Other Quantities and Units 365
End Notes 368
11 Virtual Measurement: Computerized Optical Ray Trace Analysis 371
11.1 Introduction 371
11.2 Ray Tracing in Radiometry and Photometry 374
11.3 Rays and Their Limitations in Ray Tracing Programs 374
11.4 Computerized Optical Ray Tracing Methodology 377
11.5 The Ray Tracing Process 378
11.6 Analysis of Results 383
End Notes 391
12 Basic Concepts of Colpr Science 393
12.1 Introduction 393
12.2 Basic Concepts And Definitions 394
xii Introduction to Radiometry and Photometry
12.3 Systems of Color Specification 399
12.3.1 Munsell Color System 400
12.3.2 CIE 1976 (L*a*b) Color Space 402
12.3.3 Tristimulus Colorimetry 402
12.4 CIE 1931 Color System 404
12.5 CIE 1964 Supplementary Observer Color System 409
12.6 CIE 1976 Uniform Color Space 411
12.7 Color Temperature 414
12.8 Standard Illuminants and Reflection Colorimetry 415
12.8.1 Blackbody Illuminants 417
12.8.2 Daylight Illuminants 419
12.8.3 Reflection Colorimetry 421
12.9 Color Rendering Index 422
12.10 Color Software 425
End Notes 427
Appendix A: Correspondence Between Finite
Elements and the Calculus 431
A. 1 Introduction 431
A.2 Definition of the Derivative 432
A.3 Definition of the Integral 434
A.4 Integrals As Sums 436
A.5 Sums over Solid Angles 437
End Notes 441
Appendix B Table of Physical and Mathematical Constants 443
About the Author 445
Index 447
Introduction Radiometry is a system of language, mathematics, and instrumentation used to describe and measure the propagation of electromagnetic radiation, including the effects on that radiation of reflection, refraction, absorption, transmission, and scattering by material substances in their solid, liquid, and gaseous phases.
Photometry is a system used for the same purpose when the radiation is to be detected by the human eye, so it applies to a more restricted portion of the electromagnetic spectrum.
Having the languages of radiometry and photometry helps make the definitions and explanations of various descriptive quantities precise and meaningful.
Evolution of the subject and the units used. Radiometry and photometry have evolved considerably over the long history of civilization's development of science and engineering. In the beginning, the terminology used was invented by early scientists attempting to make sense of the visible world around them. Thus, many of the early terms and units predated the more logical and consis-tent international systems of units and terminology used today, infusing the early development of this field with a possibly confusing set of names as well as units for the quantities presented in this book.
For example, the Anglo-Saxon period in England used the North German foot (335 mm or 12.2 inches in current units) as the basis unit of length and it was divided into 4 palms or 12 thumbs. A cubit was set to be 2 feet and an elne to 4 ft. The rod 05 Anglo-Saxon ft) was used for the measurement of larger distances, including the furlong (10 rods). An acre became 160 square rods and 36,000 Anglo-Saxon feet [1].
From the early English system of physical units there evolved what is currently known variously as the "inch-pound," "British imperial," and "U.S.
XIII