Preface to 2nd Edition ......................................... xv
Preface to 1st Edition ........................................ xix
Terms and Symbols ............................................. xxi
1. Introduction ................................................ 1
1.1 Applications of Optical Components ...................... 1
1.2 Key Environmental Considerations ........................ 3
1.2.1 Temperature ...................................... 3
1.2.2 Pressure ......................................... 5
1.2.3 Vibration ........................................ 6
1.2.3.1 Single frequency periodic ............... 6
1.2.3.2 Random frequencies ...................... 8
1.2.4 Shock ........................................... 10
1.2.5 Moisture, contamination, and corrosion .......... 11
1.2.6 High-energy radiation ........................... 13
1.2.7 Laser damage to optics .......................... 13
1.2.8 Abrasion and erosion ............................ 14
1.2.9 Fungus .......................................... 14
1.3 Extreme Service Environments ........................... 14
1.3.1 Near Earth's surface ............................ 14
1.3.2 In outer space .................................. 15
1.4 Environmental Testing .................................. 16
1.4.1 Guidelines ...................................... 17
1.4.2 Methods ......................................... 17
1.5 Key Material Properties ................................ 18
1.5.1 Optical glasses ................................. 19
1.5.2 Optical plastics ................................ 26
1.5.3 Optical crystals ................................ 27
1.5.4 Mirror materials ................................ 27
1.5.5 Materials for mechanical components ............. 27
1.5.6 Adhesives and sealants .......................... 29
1.6 Dimensional Instability ................................ 30
1.7 Tolerancing Optical and Mechanical Components .......... 30
1.8 Cost Aspects of Tightened Tolerances on Optics .... 33
1.9 Manufacturing Optical and Mechanical Components ... 36
1.10 References ........................................ 40
2 The Optic-to-Mount Interface ................................ 43
2.1 Mechanical Constraints ................................. 43
2.1.1 General considerations .......................... 43
2.1.2 Centering a lens element ........................ 44
2.1.3 Lens interfaces ................................. 54
2.1.3.1 The rim contact interface .............. 54
2.1.3.2 The surface contact interface .......... 55
2.1.3.3 Contacting flat bevels ................. 57
2.1.4 Prism interfaces ................................ 57
2.1.5 Mirror interfaces ............................... 60
2.1.6 Interfaces with other optical components ........ 61
2.2 Consequences of Mounting Forces ........................ 61
2.3 Sealing Considerations ................................. 61
2.4 References ............................................. 64
3 Mounting Individual Lenses .................................. 65
3.1 Preload Requirements ................................... 65
3.2 Weight and Center of Gravity Calculations .............. 68
3.3 Spring Mountings for Lenses and Filters ................ 74
3.4 Burnished Cell Mountings ............................... 75
3.5 Snap and "Interference Fit" Rings ...................... 77
3.6 Retaining Ring Constraints ............................. 84
3.6.1 Threaded retaining rings ........................ 84
3.6.2 Clamping (flange) ring .......................... 88
3.7 Constraining the Lens with Multiple Spring Clips ....... 92
3.8 Geometry of the Lens-to-Mount Interface ................ 95
3.8.1 The sharp-corner interface ...................... 95
3.8.2 The tangential (conical) interface .............. 97
3.8.3 The toroidal interface .......................... 99
3.8.4 The spherical interface ........................ 102
3.8.5 Interfaces with bevels on optics ............... 103
3.9 Elastomeric Mountings ................................. 106
3.10 Flexure Mountings for Lenses .......................... 115
3.11 Mounting Plastic Lenses ............................... 120
3.12 References ............................................ 123
4 Multiple-Component Lens Assemblies ......................... 127
4.1 Spacer Design and Manufacture ......................... 127
4.2 Drop-In Assembly ...................................... 134
4.3 Lathe Assembly ........................................ 135
4.4 Elastomeric Mountings ................................. 137
4.5 Poker-Chip Assembly ................................... 141
4.6 Assemblies Designed for High-Shock Environments ....... 142
4.7 Photographic Objective Lenses ......................... 145
4.8 Modular Construction and Assembly ..................... 152
4.9 Catoptric and Catadioptric Assemblies ................. 156
4.10 Assemblies with Plastic Housings and Lenses ........... 160
4.11 Internal Mechanisms ................................... 165
4.11.1 Focus mechanisms ............................... 165
4.11.2 Zoom mechanisms ................................ 173
4.12 Sealing and Purging Lens Assemblies .............. 176
4.13 References ....................................... 177
5 Mounting Optical Windows, Filters, Shells, and Domes ....... 179
5.1 Simple Window Mountings ............................... 179
5.2 Mounting "Special" Windows ............................ 183
5.3 Conformal Windows ..................................... 186
5.4 Windows Subject to Pressure Differential .............. 190
5.4.1 Survival ....................................... 190
5.4.2 Optical effects ................................ 195
5.5 Filter Mountings ...................................... 197
5.6 Mounting Shells and Domes ............................. 199
5.7 References ............................................ 203
6 Prism Design ............................................... 205
6.1 Principal Functions ................................... 205
6.2 Geometric Considerations .............................. 205
6.2.1 Refraction and reflection ...................... 205
6.2.2 Total internal reflection ...................... 211
6.3 Aberration Contributions of Prisms .................... 214
6.4 Typical Prism Configurations .......................... 214
6.4.1 Right-angle prism .............................. 215
6.4.2 Beamsplitter (or beamcombiner) cube prism ...... 215
6.4.3 Amici prism .................................... 216
6.4.4 Porro prism .................................... 216
6.4.5 Porro erecting system .......................... 217
6.4.6 Abbe version of the Porro prism ................ 220
6.4.7 Abbe erecting system ........................... 221
6.4.8 Rhomboid prism ................................. 221
6.4.9 Dove prism ..................................... 222
6.4.10 Double Dove prism .............................. 223
6.4.11 Reversion, Abbe Type A, and Abbe Type В
prisms ......................................... 225
6.4.12 Pechan prism ................................... 227
6.4.13 Pentaprism ..................................... 227
6.4.14 Roof penta prism ............................... 228
6.4.15 Amici/penta erecting system .................... 228
6.4.16 Delta prism .................................... 230
6.4.17 Schmidt roof prism ............................. 232
6.4.18 The 45-deg Bauernfeind prism ................... 234
6.4.19 Frankford Arsenal prisms nos. 1 and 2 .......... 234
6.4.20 Leman prism .................................... 236
6.4.21 Internally-reflecting axicon prism ............. 237
6.4.22 Cube corner prism .............................. 238
6.4.23 An ocular prism for a coincidence
rangefinder .................................... 239
6.4.24 Biocular prism system .......................... 242
6.4.25 Dispersing prisms .............................. 242
6.4.26 Thin wedge prisms .............................. 245
6.4.27 Risley wedge system ............................ 246
6.4.28 Sliding wedge .................................. 248
6.4.29 Focus-adjusting wedge system ................... 248
6.4.30 Anamorphic prism systems ....................... 250
6.5 References ............................................ 251
7 Techniques for Mounting Prisms ............................. 253
7.1 Kinematic Mountings ................................... 253
7.2 Semikinematic Mountings ............................... 254
7.3 The Use of Pads on Cantilevered and Straddling
Springs ............................................... 265
7.4 Mechanically Clamped Nonkinematic Mountings ........... 270
7.5 Bonded Prism Mountings ................................ 274
7.5.1 General considerations ......................... 274
7.5.2 Examples of bonded prisms ...................... 276
7.5.3 Double-sided prism support techniques .......... 279
7.6 Flexure Mountings for Prisms .......................... 285
7.7 References ............................................ 287
8 Mirror Design .............................................. 289
8.1 General Considerations ................................ 289
8.2 Image Orientation ..................................... 290
8.3 First- and Second-Surface Mirrors ..................... 294
8.4 Ghost Image Formation with Second-Surface Mirrors ..... 296
8.5 Approximation of Mirror Aperture ...................... 301
8.6 Weight Reduction Techniques ........................... 303
8.6.1 Contoured-back configurations .................. 304
8.6.2 Cast ribbed substrate configurations ........... 314
8.6.3 Built-up structural configurations ............. 315
8.6.3.1 Egg crate construction ................ 318
8.6.3.2 Monolithic construction ............... 319
8.6.3.3 Frit-bonded construction .............. 323
8.6.3.4 Hextek construction ................... 323
8.6.3.5 Machined core construction ............ 325
8.6.3.6 Foam core construction ................ 328
8.6.3.7 Internally machined mirror
construction .......................... 332
8.7 Thin Facesheet Configurations ......................... 334
8.8 Metallic Mirrors ...................................... 336
8.9 Metallic Foam Core Mirrors ............................ 343
8.10 Pellicles ............................................. 346
8.11 References ............................................ 348
9 Techniques for Mounting Smaller Nonmetallic Mirrors ........ 353
9.1 Mechanically Clamped Mirror Mountings ................. 353
9.2 Bonded Mirror Mountings ............................... 366
9.3 Compound Mirror Mountings ............................. 371
9.4 Flexure Mountings for Smaller Mirrors ................. 380
9.5 Central and Zonal Mountings ........................... 388
9.6 Gravitational Effects on Smaller Mirrors .............. 390
9.7 References ............................................ 396
10 Techniques for Mounting Metallic Mirrors ................... 399
10.1 Single Point Diamond Turning of Metallic Mirrors ...... 399
10.2 Integral Mounting Provisions .......................... 412
10.3 Flexure Mountings for Metallic Mirrors ................ 413
10.4 Plating of Metal Mirrors .............................. 422
10.5 Interfacing Metallic Mirrors for Assembly and
Alignment ............................................. 424
10.6 References ............................................ 429
11 Techniques for Mounting Larger Nonmetallic Mirrors ......... 433
11.1 Mounts for Axis-Horizontal Applications ............... 433
11.1.1 V-mounts ....................................... 434
11.1.2 Multipoint edge supports ....................... 441
11.1.3 The "ideal" radial mount ....................... 442
11.1.4 Strap and roller chain supports ................ 445
11.1.5 Comparison of dynamic relaxation and FEA
methods of analysis ............................ 449
11.1.6 Mercury tube supports .......................... 451
11.2 Mounts for Axis Vertical Applications ................. 452
11.2.1 General considerations ......................... 452
11.2.2 Air bag axial supports ......................... 453
11.2.3 Metrology mounts ............................... 457
11.3 Mounts for Axis Variable Applications ................. 465
11.3.1 Counterweighted lever-type mountings ........... 465
11.3.2 Hindle mounts for large mirrors ................ 471
11.3.3 Pneumatic and hydraulic mountings .............. 483
11.4 Supports for Large, Space-borne Mirrors ............... 500
11.4.1 The Hubble Space Telescope ..................... 500
11.4.2 The Chandra X-Ray Telescope .................... 503
11.5 References ............................................ 506
12 Aligning Refracting, Reflecting and Catadioptric Systems ... 511
12.1 Aligning the Individual Lens .......................... 511
12.1.1 Simple techniques for aligning a lens .......... 512
12.1.2 Rotating spindle techniques .................... 514
12.1.3 Techniques using a "Point Source Microscope" ... 520
12.2 Aligning Multiple Lens Assemblies ..................... 524
12.2 1 Using an alignment telescope ................... 525
12.2.2 Aligning microscope objectives ................. 527
12.2.3 Aligning multiple lenses on a precision
spindle ........................................ 533
12.2.4 Aberration compensation at final assembly ...... 535
12.2.5 Selecting aberration compensators .............. 543
12.3 Aligning Reflecting Systems ........................... 545
12.3.1 Aligning a simple Newtonian telescope .......... 545
12.3.2 Aligning a simple Cassegrain telescope ......... 547
12.3.3 Aligning a simple Schmidt camera ............... 549
12.4 References ............................................ 550
13 Estimation of Mounting Stresses ............................ 553
13.1 General Considerations ................................ 553
13.2 Statistical Prediction of Optic Failure ............... 554
13.3 Rule-of-Thumb Stress Tolerances ....................... 559
13.4 Stress Generation at Point, Line, and Area Contacts ... 562
13.5 Peak Contact Stress in an Annular Interface ........... 570
13.5.1 Stress with a sharp corner interface ........... 571
13.5.2 Stress with a tangential interface ............. 572
13.5.3 Stress with a toroidal interface ............... 574
13.5.4 Stress with a spherical interface .............. 576
13.5.5 Stress with a flat bevel interface ............. 576
13.5.6 Parametric comparisons of interface types ...... 576
13.6 Bending Effects in Asymmetrically Clamped Optics ...... 580
13.6.1 Bending stress in the optic .................... 580
13.6.2 Change in surface sagittal depth of a bent
optic .......................................... 582
13.7 References ............................................ 583
14 Effects of Temperature Changes ............................. 585
14.1 Athermalization Techniques for Reflective Systems ..... 585
14.1.1 Same material designs .......................... 585
14.1.2 Metering rods and trusses ...................... 586
14.2 Athermalization Techniques for Refractive Systems ..... 589
14.2.1 Passive athermalization ........................ 591
14.2.2 Active compensation ............................ 598
14.3 Effects of Temperature Change on Axial Preload ........ 602
14.3.1 Axial dimension changes ........................ 602
14.3.2 Quantifying K3 ................................. 605
14.3.2.1 Considering bulk effects only ......... 606
14.3.2.2 Considering other contributing
factors ............................... 609
14.3.3 Advantages of athermalization and compliance ... 612
14.4 Radial Effects in Rim Contact Mountings ............... 617
14.4.1 Radial stress in the optic ..................... 618
14.4.2 Tangential (hoop) stress in the mount wall ..... 620
14.4.3 Growth of radial clearance at high
temperatures ................................... 621
14.4.4 Adding radial compliance to maintain lens
centration ..................................... 622
14.5 Effects of Temperature Gradients ...................... 623
14.5 1 Radial temperature gradients ................... 627
14.5.2 Axial temperature gradients .................... 629
14.6 Temperature Change-Induced Stresses in Bonded
Optics ................................................ 630
14.7 References ............................................ 639
15 Hardware Examples .......................................... 641
15.1 Infrared Sensor Lens Assembly ......................... 641
15.2 A Family of Commercial Mid-Infrared Lenses ............ 642
15.3 Using SPDT to Mount and Align Poker Chip
Subassemblies ......................................... 643
15.4 A Dual Field IR Tracker Assembly ...................... 649
15.5 A Dual Field IR Camera Lens Assembly .................. 651
15.6 A Passively Stabilized 10:1 Zoom Lens Objective ....... 653
15.7 A 90 mm, ƒ/2 Projection Lens Assembly ................. 653
15.8 A Solid Catadioptric Lens Assembly .................... 655
15.9 An All-Aluminum Catadioptric Lens Assembly ............ 657
15.10 A Catadioptric Star Mapping Objective Assembly ....... 658
15.11 A 150-in., ƒ/10 Catadioptric Camera Objective ........ 662
15.12 The Camera Assembly for the DEIMOS Spectrograph ...... 666
15.13 Mountings for Prisms in a Military Articulated
Telescope ............................................ 668
15.14 A Modular Porro Prism Erecting System for
a Binocular .......................................... 673
15.15 Mounting Large Dispersing Prisms in a Spectrograph
Imager ............................................... 676
15.16 Mounting Gratings in the FUSE Spectrograph ........... 681
15.17 The Spitzer Space Telescope .......................... 685
15.18 A Modular Dual Collimator Assembly ................... 689
15.19 Lens Mountings for the JWST's NIRCam ................. 694
15.19.1 Concept for axial constraint of the LIF
lens ......................................... 695
15.19.2 Concept for radial constraint of the LIF
lens ......................................... 695
15.19.3 Analytical and experimental verification of
the Prototype lens mount ..................... 696
15.19.4 Design and initial testing of flight
hardware ..................................... 697
15.19.5 Long-term stability tests .................... 699
15.19.6 Further developments ......................... 699
15.20 A Double-Arch Mirror Featuring Silicon-Foam-Core-
Technology ........................................... 699
15.21 References ........................................... 704
Appendix A. Unit Conversion Factors ........................... 709
Appendix B. Mechanical Properties of Materials ................ 711
Table В1 Optomechanical properties of 50 Schott optical
glasses ............................................ 712
Table B2 Optomechanical properties of radiation resistant
Schott glasses ..................................... 715
Table B3 Selected optomechanical characteristics of
optical plastics ................................... 716
Table B4 Optomechanical properties of selected alkali
halides and alkaline earth halides ................. 717
Table B5 Optomechanical properties of selected
IR-transmitting glasses and other oxides ........... 719
Table B6 Optomechanical properties of diamond and selected
IR-transmitting semiconductor materials ............ 720
Table B7 Mechanical properties of selected IR-transmitting
chalcogenide materials ............................. 721
Table B8a Mechanical properties of selected nonmetallic
mirror substrate materials ......................... 722
Table B8b Mechanical properties of selected metallic and
composite mirror substrate materials ............... 723
Table B9 Comparison of material figures of merit for mirror
design ............................................. 724
Table В10a Characteristics of aluminum alloys used in
mirrors ............................................ 725
Table В10b Common temper conditions for aluminum alloys ....... 726
Table В10c Characteristics of aluminum matrix composites ...... 726
Table Bl0d Beryllium grades and some of their properties ...... 727
Table Bl0e Characteristics of major silicon carbide types ..... 727
Table Bll Comparison of metal matrix and polymer matrix
composites ......................................... 728
Table В12 Mechanical properties of selected metals used for
mechanical parts in optical instruments ............ 729
Table В13 Typical characteristics of a generic optical
cement ............................................. 731
Table B14 Typical characteristics of representative
structural adhesives ............................... 732
Table В15 Typical physical characteristics of
representative elastomeric sealants ................ 734
Table В16 Fracture strength SF of infrared materials ......... 736
Appendix C.Torque-Preload Relationship for a Threaded
Retaining Ring ..................................... 737
Appendix D.Summary of Methods for Testing Optical Components
and Optical Instruments under Adverse
Environmental Conditions ........................... 741
Index ......................................................... 747
CD-ROM (2nd edition) ............................ Inside back cover
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