Electro-Optical System. Analysis and Design. A Radiometry Perspective. Cornelius J. Willers SPIE PRESS. Bellingham, Washington USA

Transcription

1 Electro-Optical System Analysis and Design A Radiometry Perspective Cornelius J Willers SPIE PRESS Bellingham, Washington USA

2 Nomenclature xvii Preface xxiii 1 Electro-Optical System Design 1 11 Introduction 1 12 The Principles of Systems Design Definitions The design process 123 Prerequisites for design Product development approaches Lifecycle phases Parallel activities during development Specifications Performance measures and figures of merit Value systems and design choices Assumptions during design The design process revisited Electro-Optical Systems and System Design Definition of an electro-optical system Designing at the electro-optical-system level Electro-optical systems modeling and simulation Conclusion Introduction to Radiometry Notation Introduction Radiometry 231 Definition of quantities 23 Nomenclature Nature of radiometric quantities Spectral quantities Material properties Linear Angle 27 2 vii

3 25 Solid Angle Geometric and projected solid angle Geometric solid angle of a cone Projected solid angle of a cone Geometric solid angle of a flat rectangular surface 255 Projected solid angle of a flat rectangular surface Approximation of solid angle Projected area of a sphere Projected solid angle of a sphere Radiance and Flux Transfer Conservation of radiance Flux transfer through a lossless medium 37 medium Flux transfer through a lossy 264 Sources and receivers of arbitrary shape Multi-spectral flux transfer Lambertian Radiators and the Projected Solid Angle 28 Spatial View Factor or Configuration Factor Shape of the Radiator A disk A sphere Photometry and Color Photometry units Eye spectral response 2103 Conversion to photometric units Brief introduction to color coordinates Color-coordinate sensitivity to source spectrum Problems 53 3 Sources Planck Radiators Planck's radiation law Wien's displacement law Stefan-Boltzmann law Summation approximation of Planck's law Summary of Planck's law Thermal radiation from common objects Emissivity Kirchhoff's law Flux transfer between a source and receiver Grey bodies and selective radiators Radiation from low-emissivity 325 Emissivity surfaces 73 of cavities 74

4 ix 33 Aperture Plate in front of a Blackbody Directional Surface Reflectance Roughness and scale Reflection geometry Reflection from optically smooth surfaces Fresnel reflectance Bidirectional reflection distribution function Directional Emissivity Directional Reflectance and Emissivity in Nature The Sun Problems 91 4 Optical Media Overview Optical Mediums Lossy mediums Path radiance General law of contrast reduction Optical thickness Gas radiator sources Inhomogeneous Media and Discrete Ordinates Effective Transmittance Transmittance as Function of Range The Atmosphere as Medium Atmospheric composition and attenuation Atmospheric molecular absorption Ill 463 Atmospheric aerosols and scattering Atmospheric transmittance windows Atmospheric path radiance Practical consequences of path radiance Looking up at and looking 468 Atmospheric water-vapor down on the earth 121 content Contrast transmittance in the atmosphere Meteorological range and aerosol scattering Atmospheric Radiative Transfer Codes Overview Modtran Problems Optical Detectors Historical Overview 135

5 X 52 Overview of the Detection Process Thermal detectors Photon detectors Normalizing responsivity Detector configurations Noise Noise power spectral density Johnson noise Shot noise Generation-recombination noise //noise Temperature-fluctuation noise Interface electronics noise Noise considerations in imaging systems Signal flux fluctuation noise Background flux fluctuation noise Detector noise equivalent power and detectivity Combining power spectral densities Noise equivalent bandwidth Time-bandwidth product Thermal Detectors Principle of operation Thermal detector responsivity Resistive bolometer Pyroelectric detector Thermoelectric detector Photon-noise-limited operation Temperature-fluctuation-noise-limited operation 55 Properties of Crystalline 163 Materials Crystalline structure Occupation of electrons in energy 553 Electron density in energy bands 165 bands Semiconductor band structure Conductors, semiconductors, and insulators Intrinsic and extrinsic semiconductor materials Photon-electron interactions Light absorption in semiconductors Physical parameters for important semiconductors 56 Overview of the Photon Detection Process Photon detector operation Carriers and current flow in semiconductor material Photon absorption and majority/minority carriers 180

6 xi 564 Quantum efficiency Detector Cooling Photoconductive Detectors Introduction Photoconductive detector signal Bias circuits for photoconductive detectors Frequency response of photoconductive detectors Noise in photoconductive detectors Photovoltaic Detectors Photovoltaic detector operation Diode current-voltage relationship Bias configurations for photovoltaic detectors 594 Frequency response of a photovoltaic detector Noise in photovoltaic detectors Detector performance modeling Impact of Detector Technology on Infrared Systems 212 Problems Sensors Overview Anatomy of a Sensor Introduction to Optics Optical elements First-order ray tracing Pupils, apertures, stops, and/-number Optical sensor spatial angles Extended and point target objects Optical 637 Optical point spread aberrations 232 function Optical systems Aspheric 6310 Radiometry 64 Spectral 65 A Simple lenses 237 of a collimator 238 Filters 240 Sensor Model Sensor Signal Calculations Detector signal Source area variations Complex sources Signal Noise Reference Planes Sensor Optical Throughput Problems 250

7 7 Radiometry Techniques 71 Performance Measures Role of performance measures General definitions Commonly used performance 72 Normalization measures Solid angle spatial normalization Effective value normalization Peak normalization Weighted mapping 73 Spectral Mismatch Spectral Convolution The Range Equation 76 Pixel Irradiance in an Image Difference Contrast Pulse Detection and False Alarm Rate Validation Techniques 275 Problems Optical Signatures Model for Optical Signatures General Notes on Signatures Reflection Signatures Modeling 841 Emissivity estimation Thermal Radiators Area estimation Temperature estimation Measurement Data Analysis Case Study: High-Temperature 87 Case Study: Low-Emissivity Flame Measurement Surface Measurement Case Study: Cloud Modeling Measurements Model Relative contributions to the cloud signature Case Study: Contrast Inversion/Temperature Cross-Over Case Study: Thermally Transparent Paints Case Study: Sun-Glint Problems Electro-Optical System Analysis Case Study: Flame Sensor 309

8 xiii 92 Case Study: Object Appearance in an Image Case Study: Solar Cell Analysis Observations Analysis Case Study: Laser Rangefinder Range Equation Noise equivalent irradiance Signal irradiance Lambertian target reflectance Lambertian targets against the sky Lambertian targets against terrain Detection range Example calculation Specular reflective surfaces Case Study: Thermal Imaging Sensor Model Electronic parameters Noise expressed as D* Noise in the entrance aperture Noise in the object plane Example calculation Case Study: Atmosphere and Thermal Camera Sensitivity Case Study: Infrared Sensor Radiometry Flux on the detector Focused optics Out-of-focus optics Case Study: Bunsen Burner Flame Characterization Data analysis workflow Instrument calibration Measurements Imaging-camera 985 Imaging-camera radiance results 350 flame-area results Flame dynamics Thermocouple flame temperature results Problems Golden Rules Best Practices in Radiometric Calculation Start from First Principles Understand Radiance, Area, and Solid Angle Build Mathematical Models Work in Base SI Units Perform Dimensional Analysis Draw Pictures 368

9 the xjv 108 Understand the Role of n Simplify Spatial Integrals Graphically Plot Intermediate Results Follow Proper Coding Practices Verify and Validate Do It Right First Time! A Reference Information 375 B Infrared Scene Simulation 385 Bl Overview 385 B2 Simulation as Knowledge-Management Tool 386 B3 Simulation Validation Framework 386 B4 Optical Signature Rendering 387 B41 Image rendering 391 B42 Rendering equation 393 B5 The Effects of Super-Sampling and Aliasing 396 B6 Solar Reflection, Sky Background, and Color Ratio C Multidimensional Ray Tracing D Techniques for Numerical Solution 407 Dl Introduction 407 D2 The Requirement 407 D3 Matlab and Python as Calculators 409 D31 Matlab 410 D32 Numpy and Scipy 410 D33 Matlab and Python for radiometry calculations 410 D34 The pyradi toolkit 411 D4 Helper Functions 411 D41 Planck exitance functions 412 D42 Spectral filter function 413 D43 Spectral detector function 415 D5 Fully Worked Examples 417 D51 Flame sensor in Matlab 417 D52 Flame detector in Python 421 D53 Object appearance in an image in Python 424 D54 Color-coordinate calculations in Python 430 D55 Flame-area calculation in Matlab 434 D56 The range equation solved in Python 435

10 xv D57 Pulse detection and false alarm rate calculation 436 D58 Spatial integral of a flat plate in Matlab E Solutions to Selected Problems 441 El Solid Angle Definition 441 E2 Solid Angle Approximation 441 E3 Solid Angle Application (Problem 24) 448 E4 Flux Transfer Application 448 E5 Simple Detector System (Problem 62) 450 E6 InSb Detector Observing a Cloud (Problem 82) 451 E 7 Sensor Optimization (Problem 91) 459 F Additional Reading and Credits 471 F l Additional Reading 471 F2 Credits Index 477