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Preface xxi Glossary xxv About the Companion Website xxix

1 1 1.1 Geometrical Optics – and Wave Optics 1 1.2 Fermat’s Principle and the Eikonal Equation 2 1.3 Sequential Geometrical Optics – A Generalised Description 3 1.3.1 Conjugate Points and Perfect Image Formation 4 1.3.2 Infinite Conjugate and Focal Points 4 1.3.3 Principal Points and Planes 5 k 1.3.4 System Focal Lengths 6 k 1.3.5 Generalised Ray Tracing 6 1.3.6 Angular Magnification and Nodal Points 7 1.3.7 Cardinal Points 8 1.3.8 Object and Image Locations - Newton’s Equation 8 1.3.9 Conditions for Perfect Image Formation – Helmholtz Equation 9 1.4 Behaviour of Simple Optical Components and Surfaces 10 1.4.1 General 10 1.4.2 Refraction at a Plane Surface and Snell’s Law 10 1.4.3 Refraction at a Curved (Spherical) Surface 11 1.4.4 Refraction at Two Spherical Surfaces () 12 1.4.5 Reflection by a Plane Surface 13 1.4.6 Reflection from a Curved (Spherical) Surface 14 1.5 Paraxial Approximation and Gaussian Optics 15 1.6 Matrix Ray TracingCOPYRIGHTED16 MATERIAL 1.6.1 General 16 1.6.2 Determination of Cardinal Points 18 1.6.3 Worked Examples 18 1.6.4 Spreadsheet Analysis 21 Further Reading 21

2 Stops and Simple Instruments 23 2.1 Function of Apertures and Stops 23 2.2 Stops, Chief, and Marginal Rays 23 2.3 and Exit Pupil 25 2.4 Telecentricity 27 2.5 27 2.6 Field Stops and Other Stops 28

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2.7 Tangential and Sagittal Ray Fans 28 2.8 Two Dimensional Ray Fans and Anamorphic Optics 28 2.9 Optical Invariant and Lagrange Invariant 30 2.10 Eccentricity Variable 31 2.11 Image Formation in Simple Optical Systems 31 2.11.1 Magnifying Glass or Eye Loupe 31 2.11.2 The Compound Microscope 32 2.11.3 Simple Telescope 34 2.11.4 Camera 35 Further Reading 36

3 Monochromatic Aberrations 37 3.1 Introduction 37 3.2 Breakdown of the Paraxial Approximation and Third Order Aberrations 37 3.3 Aberration and Optical Path Difference 41 3.4 General Third Order Aberration Theory 46 3.5 Gauss-Seidel Aberrations 47 3.5.1 Introduction 47 3.5.2 Spherical Aberration 48 3.5.3 Coma 49 3.5.4 Field Curvature 51 3.5.5 Astigmatism 53 3.5.6 Distortion 54 3.6 Summary of Third Order Aberrations 55 k k 3.6.1 OPD Dependence 56 3.6.2 Transverse Aberration Dependence 56 3.6.3 General Representation of Aberration and Seidel Coefficients 57 Further Reading 58

4 Aberration Theory and 59 4.1 General Points 59 4.2 Aberration Due to a Single Refractive Surface 60 4.2.1 Aplanatic Points 61 4.2.2 Astigmatism and Field Curvature 63 4.3 Reflection from a Spherical 64 4.4 Refraction Due to Optical Components 67 4.4.1 Flat Plate 67 4.4.2 Aberrations of a Thin 69 4.4.2.1 Conjugate Parameter and Lens Shape Parameter 70 4.4.2.2 General Formulae for Aberration of Thin Lenses 71 4.4.2.3 Aberration Behaviour of a at Infinite Conjugate 72 4.4.2.4 Aplanatic Points for a Thin Lens 75 4.5 The Effect of Pupil Position on Element Aberration 78 4.6 Abbe Sine Condition 81 4.7 Chromatic Aberration 83 4.7.1 Chromatic Aberration and Optical Materials 83 4.7.2 Impact of Chromatic Aberration 84 4.7.3 The Abbe Diagram for Glass Materials 87 4.7.4 The Achromatic Doublet 87 4.7.5 Optimisation of an Achromatic Doublet (Infinite Conjugate) 89

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4.7.6 Secondary Colour 90 4.7.7 Spherochromatism 92 4.8 Hierarchy of Aberrations 92 Further Reading 94

5 Aspheric Surfaces and Zernike Polynomials 95 5.1 Introduction 95 5.2 Aspheric Surfaces 95 5.2.1 General Form of Aspheric Surfaces 95 5.2.2 Attributes of Conic 96 5.2.3 Conic Refracting Surfaces 98 5.2.4 Optical Design Using Aspheric Surfaces 99 5.3 Zernike Polynomials 100 5.3.1 Introduction 100 5.3.2 Form of Zernike Polynomials 101 5.3.3 Zernike Polynomials and Aberration 103 5.3.4 General Representation of Wavefront Error 107 5.3.5 Other Zernike Numbering Conventions 108 Further Reading 109

6 Diffraction, Physical Optics, and Image Quality 111 6.1 Introduction 111 6.2 The Eikonal Equation 112 k 6.3 Huygens Wavelets and the Diffraction Formulae 112 k 6.4 Diffraction in the Fraunhofer Approximation 115 6.5 Diffraction in an Optical System – the Airy Disc 116 6.6 The Impact of Aberration on System Resolution 120 6.6.1 The Strehl Ratio 120 6.6.2 The Maréchal Criterion 121 6.6.3 The Huygens Point Spread Function 122 6.7 Laser Beam Propagation 123 6.7.1 Far Field Diffraction of a Gaussian Laser Beam 123 6.7.2 Gaussian Beam Propagation 124 6.7.3 Manipulation of a Gaussian Beam 126 6.7.4 Diffraction and Beam Quality 127 6.7.5 Hermite Gaussian Beams 128 6.7.6 Bessel Beams 129 6.8 Fresnel Diffraction 130 6.9 Diffraction and Image Quality 132 6.9.1 Introduction 132 6.9.2 Geometric Spot Size 133 6.9.3 Diffraction and Image Quality 134 6.9.4 Modulation Transfer Function 135 6.9.5 Other Imaging Tests 137 Further Reading 138

7 Radiometry and Photometry 139 7.1 Introduction 139 7.2 Radiometry 139

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7.2.1 Radiometric Units 139 7.2.2 Significance of Radiometric Units 140 7.2.3 Ideal or Lambertian Scattering 141 7.2.4 Spectral Radiometric Units 142 7.2.5 Blackbody Radiation 142 7.2.6 Étendue 145 7.3 Scattering of Light from Rough Surfaces 146 7.4 Scattering of Light from Smooth Surfaces 147 7.5 Radiometry and Object Field Illumination 151 7.5.1 Köhler Illumination 151 7.5.2 Use of Diffusers 151 7.5.3 The Integrating Sphere 152 7.5.3.1 Uniform Illumination 152 7.5.3.2 Integrating Sphere Measurements 154 7.5.4 Natural Vignetting 154 7.6 Radiometric Measurements 155 7.6.1 Introduction 155 7.6.2 Radiometric Calibration 156 7.6.2.1 Substitution Radiometry 156 7.6.2.2 Reference Sources 156 7.6.2.3 Other Calibration Standards 157 7.7 Photometry 158 7.7.1 Introduction 158 k 7.7.2 Photometric Units 158 k 7.7.3 Illumination Levels 160 7.7.4 Colour 161 7.7.4.1 Tristimulus Values 161 7.7.4.2 RGB Colour 163 7.7.5 Astronomical Photometry 164 Further Reading 166

8 Polarisation and Birefringence 169 8.1 Introduction 169 8.2 Polarisation 170 8.2.1 Plane Polarised Waves 170 8.2.2 Circularly and Elliptically Polarised Light 170 8.2.3 Jones Vector Representation of Polarisation 172 8.2.4 Stokes Vector Representation of Polarisation 172 8.2.5 Polarisation and Reflection 175 8.2.6 Directional Flux – Poynting Vector 178 8.3 Birefringence 178 8.3.1 Introduction 178 8.3.2 The Index Ellipsoid 180 8.3.3 Propagation of Light in a Uniaxial Crystal – Double Refraction 182 8.3.4 ‘Walk-off’ in Birefringent Crystals 184 8.3.5 Uniaxial Materials 186 8.3.6 Biaxial Crystals 187 8.4 Polarisation Devices 187 8.4.1 Waveplates 187

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8.4.2 Polarising Crystals 188 8.4.3 Polarising Beamsplitter 190 8.4.4 Wire Grid Polariser 190 8.4.5 Dichroitic Materials 191 8.4.6 The Faraday Effect and Polarisation Rotation 191 8.5 Analysis of Polarisation Components 191 8.5.1 Jones Matrices 191 8.5.2 Müller Matrices 195 8.6 Stress-induced Birefringence 196 Further Reading 197

9 Optical Materials 199 9.1 Introduction 199 9.2 Refractive Properties of Optical Materials 200 9.2.1 Transmissive Materials 200 9.2.1.1 Modelling Dispersion 200 9.2.1.2 Temperature Dependence of 203 9.2.1.3 Temperature Coefficient of Refraction for Air 205 9.2.2 Behaviour of Reflective Materials 206 9.2.3 Semiconductor Materials 210 9.3 Transmission Characteristics of Materials 212 9.3.1 General 212 9.3.2 Glasses 213 k 9.3.3 Crystalline Materials 213 k 9.3.4 Chalcogenide Glasses 214 9.3.5 Semiconductor Materials 214 9.3.6 Polymer Materials 214 9.3.7 Overall Transmission Windows for Common Optical Materials 215 9.4 Thermomechanical Properties 215 9.4.1 Thermal Expansion 215 9.4.2 Dimensional Stability Under Thermal Loading 216 9.4.3 Annealing 216 9.4.4 Material Strength and Fracture Mechanics 217 9.5 Material Quality 219 9.5.1 General 219 9.5.2 Refractive Index Homogeneity 220 9.5.3 Striae 220 9.5.4 Bubbles and Inclusions 220 9.5.5 Stress Induced Birefringence 220 9.6 Exposure to Environmental Attack 221 9.6.1 Climatic Resistance 221 9.6.2 Stain Resistance 221 9.6.3 Resistance to Acid and Alkali Attack 221 9.7 Material Processing 221 Further Reading 222

10 Coatings and Filters 223 10.1 Introduction 223 10.2 Properties of Thin Films 223

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10.2.1 Analysis of Thin Film Reflection 223 10.2.2 Single Layer Antireflection Coatings 225 10.2.3 Multilayer Coatings 226 10.2.4 Thin Metal Films 229 10.2.5 Protected and Enhanced Metal Films 231 10.3 Filters 232 10.3.1 General 232 10.3.2 Antireflection Coatings 233 10.3.3 Edge Filters 233 10.3.4 Bandpass Filters 236 10.3.5 Neutral Density Filters 237 10.3.6 Polarisation Filters 238 10.3.7 Beamsplitters 240 10.3.8 Dichroic Filters 241 10.3.9 Etalon Filters 241 10.4 Design of Thin Film Filters 244 10.5 Thin Film Materials 246 10.6 Thin Film Deposition Processes 247 10.6.1 General 247 10.6.2 Evaporation 248 10.6.3 Sputtering 248 10.6.4 Thickness Monitoring 249 Further Reading 250 k k 11 Prisms and Dispersion Devices 251 11.1 Introduction 251 11.2 Prisms 251 11.2.1 Dispersive Prisms 251 11.2.2 Reflective Prisms 254 11.3 Analysis of Diffraction Gratings 257 11.3.1 Introduction 257 11.3.2 Principle of Operation 258 11.3.3 Dispersion and Resolving Power 259 11.3.4 Efficiency of a Transmission Grating 261 11.3.5 Phase Gratings 262 11.3.6 Impact of Varying Angle of Incidence 262 11.3.7 Reflection Gratings 264 11.3.8 Impact of Polarisation 268 11.3.9 Other Grating Types 269 11.3.9.1 Holographic Gratings 269 11.3.9.2 Echelle Grating 270 11.3.9.3 Concave Gratings – The Rowland Grating 270 11.3.9.4 Grisms 271 11.4 Diffractive Optics 273 11.5 Grating Fabrication 274 11.5.1 Ruled Gratings 274 11.5.2 Holographic Gratings 275 Further Reading 276

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12 Lasers and Laser Applications 277 12.1 Introduction 277 12.2 Stimulated Emission Schemes 279 12.2.1 General 279 12.2.2 Stimulated Emission in Ruby 279 12.2.3 Stimulated Emission in Neon 280 12.2.4 Stimulated Emission in Semiconductors 282 12.3 Laser Cavities 284 12.3.1 Background 284 12.3.2 Longitudinal Modes 285 12.3.3 Longitudinal Mode Phase Relationship – Mode Locking 287 12.3.4 Q Switching 288 12.3.5 Distributed Feedback 289 12.3.6 Ring Lasers 289 12.3.7 Transverse Modes 290 12.3.8 Gaussian Beam Propagation in a Laser Cavity 291 12.4 Taxonomy of Lasers 293 12.4.1 General 293 12.4.2 Categorisation 293 12.4.2.1 Gas Lasers 293 12.4.2.2 Solid State Lasers 293 12.4.2.3 Fibre Lasers 294 12.4.2.4 Semiconductor Lasers 294 k 12.4.2.5 Chemical Lasers 294 k 12.4.2.6 Dye Lasers 295 12.4.2.7 Optical Parametric Oscillators and Non-linear Devices 295 12.4.2.8 Other Lasers 296 12.4.3 Temporal Characteristics 297 12.4.4 Power 297 12.5 List of Laser Types 298 12.5.1 Gas Lasers 298 12.5.2 Solid State Lasers 298 12.5.3 Semiconductor Lasers 298 12.5.4 Chemical Lasers 298 12.5.5 Dye Lasers 299 12.5.6 Other Lasers 300 12.6 Laser Applications 301 12.6.1 General 301 12.6.2 Materials Processing 301 12.6.3 Lithography 303 12.6.4 Medical Applications 303 12.6.5 Surveying and Dimensional Metrology 304 12.6.6 Alignment 305 12.6.7 Interferometry and Holography 306 12.6.8 Spectroscopy 306 12.6.9 Data Recording 307 12.6.10 Telecommunications 307 Further Reading 308

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13 Optical Fibres and Waveguides 309 13.1 Introduction 309 13.2 Geometrical Description of Fibre Propagation 310 13.2.1 Step Index Fibre 310 13.2.2 Graded Index Optics 311 13.2.2.1 Graded Index Fibres 311 13.2.2.2 Gradient Index Optics 313 13.2.3 Fibre Bend Radius 316 13.3 Waveguides and Modes 317 13.3.1 Simple Description – Slab Modes 317 13.3.2 Propagation Velocity and Dispersion 320 13.3.3 Strong and Weakly Guiding Structures 323 13.4 Single Mode Optical Fibres 324 13.4.1 Basic Analysis 324 13.4.2 Generic Analysis of Single Mode Fibres 326 13.4.3 Impact of Fibre Bending 328 13.5 Optical Fibre Materials 329 13.5.1 General 329 13.5.2 Attenuation 329 13.5.3 Fibre Dispersion 330 13.6 Coupling of Light into Fibres 330 13.6.1 General 330 13.6.2 Coupling into Single Mode Fibres 332 k 13.6.2.1 Overlap Integral 332 k 13.6.2.2 Coupling of Gaussian Beams into Single Mode Fibres 332 13.7 Fibre Splicing and Connection 334 13.8 Fibre Splitters, Combiners, and Couplers 335 13.9 Polarisation and Polarisation Maintaining Fibres 335 13.9.1 Polarisation Mode Dispersion 335 13.9.2 Polarisation Maintaining Fibre 336 13.10 Focal Ratio Degradation 336 13.11 Periodic Structures in Fibres 336 13.11.1 Photonic Crystal Fibres and Holey Fibres 336 13.11.2 Fibre Bragg Gratings 337 13.12 Fibre Manufacture 338 13.13 Fibre Applications 339 Further Reading 339

14 Detectors 341 14.1 Introduction 341 14.2 Detector Types 341 14.2.1 Photomultiplier Tubes 341 14.2.1.1 General Operating Principle 341 14.2.1.2 Dynode Multiplication 343 14.2.1.3 Spectral Sensitivity 343 14.2.1.4 Dark Current 344 14.2.1.5 Linearity 345 14.2.1.6 Photon Counting 345

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14.2.2 Photodiodes 345 14.2.2.1 General Operating Principle 345 14.2.2.2 Sensitivity 346 14.2.2.3 Dark Current 348 14.2.2.4 Linearity 348 14.2.2.5 Breakdown 348 14.2.3 Avalanche Photodiode 349 14.2.4 Array Detectors 350 14.2.4.1 Introduction 350 14.2.4.2 Charged Coupled Devices 350 14.2.4.3 CMOS (Complementary Metal Oxide Semiconductor) Technology 350 14.2.4.4 Sensitivity 351 14.2.4.5 Dark Current 351 14.2.4.6 Linearity 352 14.2.5 Photoconductive Detectors 352 14.2.6 Bolometers 353 14.3 Noise in Detectors 354 14.3.1 Introduction 354 14.3.2 Shot Noise 355 14.3.3 Gain Noise 356 14.3.4 Background Noise 356 14.3.5 Dark Current 357 14.3.6 Johnson Noise 357 k 14.3.6.1 General 357 k 14.3.6.2 Johnson Noise in Array Detectors 359 14.3.7 Pink or ‘Flicker’ Noise 361 14.3.8 Combining Multiple Noise Sources 362 14.3.9 Detector Sensitivity 363 14.4 Radiometry and Detectors 364 14.5 Array Detectors in Instrumentation 365 14.5.1 Flat Fielding of Array Detectors 365 14.5.2 Image Centroiding 366 14.5.3 Array Detectors and MTF 367 Further Reading 368

15 Optical Instrumentation – Imaging Devices 369 15.1 Introduction 369 15.2 The Design of Eyepieces 370 15.2.1 Underlying Principles 370 15.2.2 Simple Eyepiece Designs – Huygens and Ramsden Eyepieces 371 15.2.3 Kellner Eyepiece 372 15.2.4 Plössl Eyepiece 374 15.2.5 More Complex Designs 375 15.3 Microscope Objectives 378 15.3.1 Background to Objective Design 378 15.3.2 Design of Microscope Objectives 380 15.4 Telescopes 381 15.4.1 Introduction 381

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15.4.2 Refracting Telescopes 382 15.4.3 Reflecting Telescopes 383 15.4.3.1 Introduction 383 15.4.3.2 Simple Reflecting Telescopes 383 15.4.3.3 Ritchey-Chrétien Telescope 385 15.4.3.4 Three Mirror Anastigmat 388 15.4.3.5 Quad Mirror Anastigmat 391 15.4.4 Catadioptric Systems 391 15.5 Camera Systems 392 15.5.1 Introduction 392 15.5.2 Simple Camera Lenses 394 15.5.3 Advanced Designs 395 15.5.3.1 Cooke Triplet 395 15.5.3.2 Variations on the Cooke Triplet 398 15.5.3.3 Double Gauss Lens 398 15.5.3.4 Zoom Lenses 401 Further Reading 405

16 Interferometers and Related Instruments 407 16.1 Introduction 407 16.2 Background 407 16.2.1 Fringes and Fringe Visibility 407 16.2.2 Data Processing and Wavefront Mapping 409 k 16.3 Classical Interferometers 409 k 16.3.1 The Fizeau Interferometer 409 16.3.2 The Twyman Green Interferometer 410 16.3.3 Mach-Zehnder Interferometer 411 16.3.4 Lateral Shear Interferometer 412 16.3.5 White Light Interferometer 413 16.3.6 Interference Microscopy 416 16.3.7 Vibration Free Interferometry 416 16.4 Calibration 418 16.4.1 Introduction 418 16.4.2 Calibration and Characterisation of Reference Spheres 418 16.4.3 Characterisation and Calibration of Reference Flats 419 16.5 Interferometry and Null Tests 420 16.5.1 Introduction 420 16.5.2 Testing of Conics 421 16.5.3 Null Lens Tests 422 16.5.4 Computer Generated Holograms 424 16.6 Interferometry and Phase Shifting 425 16.7 Miscellaneous Characterisation Techniques 426 16.7.1 Introduction 426 16.7.2 Shack-Hartmann Sensor 427 16.7.3 Knife Edge Tests 428 16.7.4 Fringe Projection Techniques 429 16.7.5 Scanning Pentaprism Test 431 16.7.6 Confocal Gauge 432 Further Reading 433

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17 Spectrometers and Related Instruments 435 17.1 Introduction 435 17.2 Basic Spectrometer Designs 436 17.2.1 Introduction 436 17.2.2 Grating Spectrometers and Order Sorting 436 17.2.3 Czerny Turner Monochromator 436 17.2.3.1 Basic Design 436 17.2.3.2 Resolution 438 17.2.3.3 Aberrations 439 17.2.3.4 Flux and Throughput 442 17.2.3.5 Instrument Scaling 443 17.2.4 Fastie-Ebert Spectrometer 444 17.2.5 Offner Spectrometer 444 17.2.6 Imaging Spectrometers 445 17.2.6.1 Introduction 445 17.2.6.2 Spectrometer Architecture 446 17.2.6.3 Spectrometer Design 447 17.2.6.4 Flux and Throughput 449 17.2.6.5 Straylight and Ghosts 450 17.2.6.6 2D Object Conditioning 450 17.2.7 Echelle Spectrometers 452 17.2.8 Double and Triple Spectrometers 453 17.3 Time Domain Spectrometry 454 k 17.3.1 Fourier Transform Spectrometry 454 k 17.3.2 Wavemeters 456 Further Reading 457

18 Optical Design 459 18.1 Introduction 459 18.1.1 Background 459 18.1.2 Tolerancing 459 18.1.3 Design Process 460 18.1.4 Optical Modelling – Outline 460 18.1.4.1 Sequential Modelling 460 18.1.4.2 Non-Sequential Modelling 461 18.2 Design Philosophy 461 18.2.1 Introduction 461 18.2.2 Definition of Requirements 462 18.2.3 Requirement Partitioning and Budgeting 463 18.2.4 Design Process 465 18.2.5 Summary of Design Tools 465 18.3 Optical Design Tools 467 18.3.1 Introduction 467 18.3.2 Establishing the Model 467 18.3.2.1 Lens Data Editor 467 18.3.2.2 System Parameters 471 18.3.2.3 Co-ordinates 471 18.3.2.4 Merit Function Editor 472 18.3.3 Analysis 473

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18.3.4 Optimisation 476 18.3.5 Tolerancing 478 18.3.5.1 Background 478 18.3.5.2 Tolerance Editor 479 18.3.5.3 Sensitivity Analysis 480 18.3.5.4 Monte-Carlo Simulation 481 18.3.5.5 Refining the Tolerancing Model 482 18.3.5.6 Default Tolerances 483 18.3.5.7 Registration and Mechanical Tolerances 485 18.3.5.8 Sophisticated Modelling of Form Error 486 18.4 Non-Sequential Modelling 487 18.4.1 Introduction 487 18.4.2 Applications 488 18.4.3 Establishing the Model 488 18.4.3.1 Background and Model Description 488 18.4.3.2 Lens Data Editor 489 18.4.3.3 Wavelengths 491 18.4.3.4 Analysis 491 18.4.4 Baffling 493 18.5 Afterword 495 Further Reading 495

19 Mechanical and Thermo-Mechanical Modelling 497 k 19.1 Introduction 497 k 19.1.1 Background 497 19.1.2 Tolerancing 498 19.1.3 Athermal Design 498 19.1.4 Mechanical Models 498 19.2 Basic Elastic Theory 498 19.2.1 Introduction 498 19.2.2 Elastic Theory 499 19.3 Basic Analysis of Mechanical Distortion 501 19.3.1 Introduction 501 19.3.2 Optical Bench Distortion 501 19.3.2.1 Definition of the Problem 501 19.3.2.2 Application of External Forces 503 19.3.2.3 Establishing Boundary Conditions 504 19.3.2.4 Modelling of Deflection under Self-Loading 505 19.3.2.5 Modelling of Deflection Under ‘Point’ Load 506 19.3.2.6 Impact of Optical Bench Distortion 507 19.3.3 Simple Distortion of Optical Components 508 19.3.3.1 Introduction 508 19.3.3.2 Self-Weight Deflection 509 19.3.3.3 Vacuum or Pressure Flexure 510 19.3.4 Effects of Component Mounting 512 19.3.4.1 General 512 19.3.4.2 Degrees of Freedom in Mounting 512 19.3.4.3 Modelling of Mounting Deformation in Mirrors 513 19.3.4.4 Modelling of Mounting Stresses in Lens Components 515

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19.4 Basic Analysis of Thermo-Mechanical Distortion 517 19.4.1 Introduction 517 19.4.2 Thermal Distortion of Optical Benches 518 19.4.3 Impact of Focal Shift and Athermal Design 520 19.4.4 Differential Expansion of a Component Stack 521 19.4.5 Impact of Mounting and Bonding 521 19.4.5.1 Bonding 521 19.4.5.2 Mounting 522 19.5 Finite Element Analysis 525 19.5.1 Introduction 525 19.5.2 Underlying Mechanics 526 19.5.2.1 Definition of Static Equilibrium 526 19.5.2.2 Boundary Conditions 527 19.5.3 FEA Meshing 527 19.5.4 Some FEA Models 529 Further Reading 529

20 Optical Component Manufacture 531 20.1 Introduction 531 20.1.1 Context 531 20.1.2 Manufacturing Processes 531 20.2 Conventional Figuring of Optical Surfaces 532 20.2.1 Introduction 532 k 20.2.2 Grinding Process 533 k 20.2.3 Fine Grinding 535 20.2.4 Polishing 535 20.2.5 Metrology 537 20.3 Specialist Shaping and Polishing Techniques 539 20.3.1 Introduction 539 20.3.2 Computer-Controlled Sub-Aperture Polishing 539 20.3.3 Magneto-rheological Polishing 540 20.3.4 Ion Beam Figuring 541 20.4 Diamond Machining 541 20.4.1 Introduction 541 20.4.2 Basic Construction of a Diamond Machine Tool 543 20.4.3 Machining Configurations 544 20.4.3.1 Single Point Diamond Turning 544 20.4.3.2 Raster Flycutting 545 20.4.4 Fixturing and Stability 546 20.4.5 Moulding and Replication 547 20.5 Edging and Bonding 547 20.5.1 Introduction 547 20.5.2 Edging of Lenses 548 20.5.3 Bonding 549 20.6 Form Error and Surface Roughness 550 20.7 Standards and Drawings 551 20.7.1 Introduction 551 20.7.2 ISO 10110 552 20.7.2.1 Background 552

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20.7.2.2 Material Properties 552 20.7.2.3 Surface Properties 553 20.7.2.4 General Information 555 20.7.3 Example Drawing 557 Further Reading 557

21 System Integration and Alignment 559 21.1 Introduction 559 21.1.1 Background 559 21.1.2 Mechanical Constraint 559 21.1.3 Mounting Geometries 560 21.2 Component Mounting 561 21.2.1 Lens Barrel Mounting 561 21.2.2 Optical Bench Mounting 563 21.2.2.1 General 563 21.2.2.2 Kinematic Mounts 563 21.2.2.3 Gimbal Mounts 565 21.2.2.4 Flexure Mounts 565 21.2.2.5 Hexapod Mounting 567 21.2.2.6 Linear Stages 567 21.2.2.7 Micropositioning and Piezo-Stages 570 21.2.3 Mounting of Large Components and Isostatic Mounting 570 21.3 Optical Bonding 573 k 21.3.1 Introduction 573 k 21.3.2 Material Properties 574 21.3.3 Adhesive Curing 575 21.3.4 Applications 575 21.3.5 Summary of Adhesive Types and Applications 577 21.4 Alignment 577 21.4.1 Introduction 577 21.4.2 Alignment and Boresight Error 578 21.4.3 Alignment and Off-Axis Aberrations 579 21.4.4 Autocollimation and Alignment 579 21.4.5 Alignment and Spot Centroiding 581 21.4.6 Alignment and Off-Axis Aberrations 582 21.5 Cleanroom Assembly 583 21.5.1 Introduction 583 21.5.2 Cleanrooms and Cleanroom Standards 583 21.5.3 Particle Deposition and Surface Cleanliness 584 Further Reading 586

22 Optical Test and Verification 587 22.1 Introduction 587 22.1.1 General 587 22.1.2 Verification 587 22.1.3 Systems, Subsystems, and Components 587 22.1.4 Environmental Testing 588 22.1.5 Optical Performance Tests 589 22.2 Facilities 589

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22.3 Environmental Testing 591 22.3.1 Introduction 591 22.3.2 Dynamical Tests 592 22.3.2.1 Vibration 592 22.3.2.2 Mechanical Shock 593 22.3.3 Thermal Environment 593 22.3.3.1 Temperature and Humidity Cycling 593 22.3.3.2 Thermal Shock 595 22.4 Geometrical Testing 595 22.4.1 Introduction 595 22.4.2 and Cardinal Point Determination 595 22.4.3 Measurement of Distortion 599 22.4.4 Measurement of Angles and Displacements 599 22.4.4.1 General 599 22.4.4.2 Calibration 601 22.4.4.3 Co-ordinate Measurement Machines 602 22.5 Image Quality Testing 603 22.5.1 Introduction 603 22.5.2 Direct Measurement of Image Quality 603 22.5.3 Interferometry 604 22.6 Radiometric Tests 604 22.6.1 Introduction 604 22.6.2 Detector Characterisation 605 k 22.6.2.1 General 605 k 22.6.2.2 Pixelated Detector Flat Fielding 605 22.6.3 Measurement of Spectral Irradiance and Radiance 606 22.6.4 Characterisation of Spectrally Dependent Flux 607 22.6.5 Straylight and Low Light Levels 607 22.6.6 Polarisation Measurements 608 22.7 Material and Component Testing 609 22.7.1 Introduction 609 22.7.2 Material Properties 609 22.7.2.1 Measurement of Refractive Index 609 22.7.2.2 Bubbles and Inclusions 610 22.7.3 Surface Properties 610 22.7.3.1 Measurement of Surface Roughness 610 22.7.3.2 Measurement of Cosmetic Surface Quality 611 Further Reading 612

Index 613

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