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Library of Congress Cataloging-in-Publication Data Daniels, Arnold. Field guide to infrared systems / Arnold Daniels. p. cm.-- (The Field guide series ; no. 1:9) Includes bibliographical references and index. ISBN 0-8194-6361-2 (alk. paper) 1. Infrared technology--Handbooks, manuals, etc. I. Title. II. Series: Field guide series (Bellingham, Wash.) ; no. 1:9. TA1570.D36 2006 621.36'2--dc22 2006015467 Published by SPIE—The International Society for Optical Engineering P.O. Box 10 Bellingham, Washington 98227-0010 USA Phone: +1 360 676 3290 Fax: +1 360 647 1445 Email: spie@spie.org Web: http://spie.org The content of this book reflects the work and thought of the author. 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. Introduction to the SeriesWelcome to the SPIE Field Guides —a series of publications written directly for the practicing engineer or scientist. Many textbooks and professional reference books cover optical principles and techniques in depth. The aim of the SPIE Field Guides is to distill this information, providing readers with a handy desk or briefcase reference that provides basic, essential information about optical principles, techniques, or phenomena, including definitions and descriptions, key equations, illustrations, application examples, design considerations, and additional resources. Asig-nificant effort will be made to provide a consistent notation and style between volumes in the series. Each SPIE Field Guide addresses a major field of optical science and technology. The concept of these Field Guides is a format-intensive presentation based on figures and equations supplemented by concise explanations. In most cases, this modular approach places a single topic on a page, and provides full coverage of that topic on that page. Highlights, insights, and rules of thumb are displayed in sidebars to the main text. The appendices at the end of each Field Guide provide additional information such as related material outside the main scope of the volume, key mathematical relationships, and alternative methods. While complete in their coverage, the concise presentation may not be appropriate for those new to the field. The SPIE Field Guides are intended to be living documents. The modular page-based presentation format allows them to be easily updated and expanded. We are interested in your suggestions for new Field Guide topics as well as what material should be added to an individual volume to make these Field Guides more useful to you. Please contact us at fieldguides@SPIE.org. John E. Greivenkamp, Series Editor Optical Sciences Center The University of Arizona The Field Guide SeriesKeep information at your fingertips with all of the titles in the Field Guide Series: Field Guide to Geometrical Optics, John E. Greivenkamp (FG01) Field Guide to Atmospheric Optics, Larry C. Andrews (FG02) Field Guide to Adaptive Optics, Robert K. Tyson and Benjamin W. Frazier (FG03) Field Guide to Visual and Ophthalmic Optics, Jim Schwiegerling (FG04) Field Guide to Polarization, Edward Collett (FG05) Field Guide to Optical Lithography, Chris A. Mack (FG06) Field Guide to Optical Thin Films, Ronald R. Willey (FG07) Field Guide to Spectroscopy, David W. Ball (FG08) Field Guide to Infrared Systems, Arnold Daniels (FG09) Field Guide to Interferometric Optical Testing,EricP. Goodwin and James C. Wyant (FG10) Field Guide to Infrared SystemsField Guide to Infrared Systems is written to clarify and summarize the theoretical principles of infrared technology. It is intended as a reference work for the practicing engineer and/or scientist who requires effective practical information to design, build, and/or test infrared equipment in a wide variety of applications. This book combines numerous engineering disciplines necessary for the development of an infrared system. It describes the basic elements involving image formation and image quality, radiometry and flux transfer, and explains the figures of merit involving detector performance. It considers the development of search infrared systems, and specifies the main descriptors used to characterize thermal imaging systems. Furthermore, this guide clarifies, identifies, and evaluates the engineering tradeoffs in the design of an infrared system. I would like to acknowledge and express my gratitude to my professor and mentor Dr. Glenn Boreman for his guidance, experience, and friendship. The knowledge that he passed on to me during my graduate studies at CREOL ultimately contributed to the creation of this book. Thanks are extended to Merry Schnell for her hard work and dedication on this project. I voice a special note of gratitude to my kids Becky and Alex for their forbearance, and to my wife Rosa for her love and support. Lastly, I would particularly like to thank you, the reader, for selecting this book and taking the time to explore the topics related to this motivating and exciting field. I truly hope that you will find the contents of this book interesting and informative. This Field Guide is dedicated to the memory of my father and brothers. Arnold Daniels Table of ContentsGlossary x Introduction 1 Electromagnetic Spectrum 1 Infrared Concepts 2 Optics 3 Imaging Concepts 3 Magnification Factors 4 Thick Lenses 5 Stop and Pupils 6 F -number and Numerical Aperture 7 Field-of-View 8 Combination of Lenses 9 Afocal Systems and Refractive Telescopes 10 Cold-Stop Efficiency and Field Stop 11 Image Quality 12 Image Anomalies in Infrared Systems 14 Infrared Materials 15 Material Dispersion 19 Atmospheric Transmittance 21 Radiometry and Sources 22 Solid Angle 22 Radiometry 23 Radiometric Terms 24 Flux Transfer 26 Flux Transfer for Image-Forming Systems 27 Source Configurations 28 Blackbody Radiators 30 Planck's Radiation Law 31 Stefan-Boltzmann and Wien's Displacement Laws 33 Rayleigh-Jeans and Wien's Radiation Laws 34 Exitance Contrast 35 Emissivity 36 Kirchhoff's Law 37 Emissivity of Various Common Materials 38 Radiometric Measure of Temperature 39 Collimators 41 Performance Parameters for Optical Detectors 42 Infrared Detectors 42 Primary Sources of Detector Noise 43 Noise Power Spectral Density 44 White Noise 45 Noise-Equivalent Bandwidth 46 Shot Noise 48 Signal-to-Noise Ratio: Detector and BLIP Limits 49 Generation-Recombination Noise 50 Johnson Noise 51 1/f Noise and Temperature Noise 52 Detector Responsivity 53 Spectral Responsivity 55 Blackbody Responsivity 56 Noise Equivalent Power 57 Specific or Normalized Detectivity 58 Photovoltaic Detectors or Photodiodes 59 Sources of Noise in PV Detectors 60 Expressions for , , and 61 Photoconductive Detectors 62 Sources of Noise in PC Detectors 63 Pyroelectric Detectors 64 Bolometers 66 Bolometers: Immersion Optics 68 Thermoelectic Detectors 69 Infrared Systems 70 Raster Scan Format: Single-Detector 70 Multiple-Detector Scan Formats: Serial Scene Dissection 72 Multiple-Detector Scan Formats: Parallel Scene Dissection 73 Staring Systems 74 Search Systems and Range Equation 75 Noise Equivalent Irradiance 78 Performance Specification: Thermal-Imaging Systems 79 MTF Definitions 80 Optics MTF: Calculations 83 Electronics MTF: Calculations 85 MTF Measurement Setup and Sampling Effects 86 MTF Measurement Techniques: PSF and LSF 87 MTF Measurement Techniques: ESF and CTF 88 MTF Measurement Techniques: Noiselike Targets 90 MTF Measurement Techniques: Interferometry 92 Noise Equivalent Temperature Difference 93 NETD Measurement Technique 94 Minimum Resolvable Temperature Difference 95 MRTD: Calculation 96 MRTD Measurement Technique 97 MRTD Measurement: Automatic Test 98 Johnson Criteria 99 Infrared Applications 101 Appendix Equation Summary 103 Notes 112 Bibliography 113 Index 116 GlossaryA Area Ad Detector area Aenp Area of an entrance-pupil Aexp Area of an exit-pupil Afootprint Footprint area Aimg Area of an image Alens Lens area Aobj Area of an object Aopt Area of an optical component As Source area B 3-db bandwidth c Speed of light in vacuum Cd Detector capacitance CTF Contrast transfer function ddiff Diameter of a diffraction-limited spot D* Normalized detectivity of a detector D-star under BLIP conditions D** Angle-normalized detectivity Denp Diameter of an entrance-pupil Dexp Diameter of an exit-pupil Dimg Image diameter Din Input diameter Dlens Lens diameter Dout Output diameter Dobj Object diameter Dopt Optics diameter e Energy-based unit subscript Ebkg Background irradiance Eimg Image irradiance Esource Source irradiance ESF Edge spread function ε Energy of a photon feff Effective focal length f Focal length b.f .l Back focal length f .f .l Front focal length f (x, y) Object function FB Back focal point FF Front focal point F(ξ, η) Object spectrum fo Center frequency of an electrical filter FOV Full-angle field-of-view FOVhalf-angle Half-angle field-of-view F/# F-number g(x, y) Image function G(ξ, η) Image spectrum G Gain of a photoconductive detector h(x, y) Impulse response H(ξ, η) Transfer function h Planck's constant H Heat capacity HIFOV Horizontal instantaneous field-of-view HFOV Horizontal field-of-view himg Image height hobj Object height i Electrical current Mean current iavg Average electrical current ibkg Background rms current idark Dark current ij rms Johnson noise current i1/f rms 1 /f-noise current iG/R Generation-recombination noise rms current inoise Noise current ioc Open circuit current ipa Preamplifier noise rms current irms rms current isc Short circuit current ishot Shot noise rms current isig Signal current J Current density k Boltzmann's constant κ(ξf) Spatial-frequency dependant MRTD pro-portionality factor K Thermal conductance L Radiance LSF Line spread function Lbkg Back round radiance Lλ Spectral radiance M Exitance Mmeas Measured exitance Mobj Exitance of an object Mλ Spectral exitance MRTD Minimum resolvable temperature difference MTF Modulation transfer function MTFd Detector MTF ℳ Magnification ℳang Angular magnification n Refractive index nd Number of detectors ne Number of photogenerated electrons nlines Number of lines NEI Noise-equivalent irradiance NEP Noise-equivalent power NEΔf Noise-equivalent bandwidth OTF Optical transfer function Pavg Average power p Object distance PSD Power spectral density PSF Point spread function q Image distance R Resistance Rd Detector resistance Req Equivalent resistance Rin Input resistance RL Load resistance Rout Output resistance SNR Signal-to-noise ratio SR Strehl-intensity ratio 𝓡 Responsivity 𝓡i Current responsivity 𝓡υ Voltage responsivity 𝓡(λ) Spectral responsivity 𝓡(T) Blackbody responsivity t Time T Temperature TB Brightness temperature Tbkg Background temperature TC Color temperature Td Detector temperature Tload Load temperature Trad Radiation temperature Tsource Source temperature Ttarget Target temperature VIFOV Vertical instantaneous field-of-view VFOV Vertical field-of-view Mean voltage υin Input voltage υj Johnson noise rms voltage υn rms noise voltage υoc Open-circuit voltage υout Output voltage υsc Short-circuit voltage υs Shot-noise rms voltage υscan Scan velocity υsig Signal voltage V Abbe number W W proportionality factor α Coefficient of absorption β Blur angle caused by diffraction ε Emissivity Δf Electronic frequency bandwidth Δt Time interval ΔT Temperature difference Δλ Wavelength interval θ Angle variable θmax Maximum angle subtense η Quantum efficiency ηscan Scan efficiency λ Wavelength λcut Cutoff wavelength λmax Maximum wavelength λmax-cont Maximum contrast wavelength λpeak Peak wavelength λo Fixed wavelength ν Optical frequency σ2 Variance σ Standard deviation σe Stefan-Boltzmann constant in energy units σP Stefan-Boltzmann constant in photon units ρ Reflectance τ Transmittance τatm Atmospheric transmittance τdwell Dwell time τext External transmittance τint Internal transmittance τframe Frame time τline Line time τopt Optical transmittance Φ Flux Φλ Spectral flux Φabs Absorbed flux Φbkg Background flux Φd Detector flux Φimg Flux incident on an image Φinc Incident flux Φobj Flux radiated by an object Φref Reflected flux φsig Signal flux Φtrans Transmitted flux ξ Spatial frequency in x-direction ξcutoff Spatial cutoff frequency η Spatial frequency in y-direction Ω Solid angle Ωd Detector solid angle Ωs Source solid angle Ωbkg Background solid angle Ωexp Exit pupil solid angle Ωenp Entrance pupil solid angle Ωimg Image solid angle Ωlens Lens solid angle Ωobj Object solid angle |
CITATIONS
Thermography
Infrared radiation
Signal to noise ratio
Interference (communication)
Infrared imaging
Modulation transfer functions
Imaging systems
