Spie Press BookMounting Optics in Optical Instruments, 2nd Edition
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Expand your knowledge of Optics in Optical Instruments by taking the SPIE course Introduction to Optomechanical Design, with instructor Daniel Vukobratovich.Click here to register.
Be sure to take the SPIE course Mounting Optical Components, with instructor Keith Kasunic. The contents of the course are based on this book! Click here to register.
Entirely updated to cover the latest technology, this second edition gives optical designers and optomechanical engineers a thorough understanding of the principal ways in which optical components--lenses, windows, filters, shells, domes, prisms, and mirrors of all sizes--are mounted in optical instruments.
Along with new information on tolerancing, sealing considerations, elastomeric mountings, alignment, stress estimation, and temperature control, two new chapters address the mounting of metallic mirrors and the alignment of reflective and catadioptric systems.
The updated accompanying supplemental material offers a convenient spreadsheet of the many equations that are helpful in solving problems encountered when mounting optics in instruments.
- Preface to 2nd Edition
- Preface to 1st Edition
- Terms and Symbols
- 1. Introduction/1
- 1.1 Applications of Optical Components/ 1
- 1.2 Key Environmental Considerations/ 2
- 1.2.1 Temperature/ 3
- 1.2.2 Pressure/ 4
- 1.2.3 Vibration/ 5
- 22.214.171.124 Single frequency periodic/6
- 126.96.36.199 Random frequencies/ 8
- 1.2.4 Shock/ 9
- 1.2.5 Moisture, contamination, and corrosion/11
- 1.2.6 High-energy radiation/12
- 1.2.7 Laser damage to optics/12
- 1.2.8 Abrasion and erosion/13
- 1.2.9 Fungus/13
- 1.3 Extreme service environments/14
- 1.3.1 Near Earth's surface/14
- 1.3.2 In outer space/14
- 1.4 Environmental Testing/16
- 1.4.1 Guidelines/16
- 1.4.2 Methods/16
- 1.5 Key Material Properties/18
- 1.5.1 Optical glasses/19
- 1.5.2 Optical plastics/26
- 1.5.3 Optical crystals/26
- 1.5.4 Mirror materials/26
- 1.5.5 Materials for mechanical components/27
- 1.5.6 Adhesives and sealants/28
- 1.6 Dimensional Instability/29
- 1.7 Tolerancing Optical and Mechanical Components/32
- 1.8 Cost Aspects of Tightened Tolerances on Optics/32
- 1.9 Manufacturing Optical and Mechanical Components/36
- 2. The Optic-to-Mount Interface/45
- 2.1 Mechanical Constraints/45
- 2.1.1 General considerations/45
- 2.1.2 Centering a lens element/46
- 2.1.3 Lens interfaces/55
- 188.8.131.52 The rim contact interface/55
- 184.108.40.206 The surface contact interface/57
- 220.127.116.11 Contacting flat bevels/59
- 2.1.4 Prism interfaces/59
- 2.1.5 Mirror interfaces/62
- 2.1.6 Interfaces with other optical components/63
- 2.2 Consequences of Mounting Forces/63
- 2.3 Sealing Considerations/63
- 3. Mounting Individual Lenses/67
- 3.1 Preload Requirements/67
- 3.2 Weight and Center of Gravity Calculations/70
- 3.3 Spring Mountings for Lenses and Filters/75
- 3.4 Burnished Cell Mountings/77
- 3.5 Snap and "Interference Fit" Rings/78
- 3.6 Retaining Ring Constraints/85
- 3.6.1 Threaded retaining rings/85
- 3.6.2 Clamping (flange) ring/89
- 3.7 Constraining the Lens with Multiple Spring Clips/93
- 3.8 Geometry of the Lens-to-Mount Interface/96
- 3.8.1 The sharp corner interface/96
- 3.8.2 The tangential (conical) interface/97
- 3.8.3 The toroidal interface/100
- 3.8.4 The spherical interface/103
- 3.8.5 Interfaces with bevels on optics/104
- 3.9 Elastomeric Mountings/107
- 3.10 Flexure Mountings for Lenses/115
- 3.11 Mounting Plastic Lenses/120
- 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/146
- 4.8 Modular Construction and Assembly/153
- 4.9 Catoptric and Catadioptric Assemblies/158
- 4.10 Assemblies with Plastic Housings and Lenses/162
- 4.11 Internal Mechanisms/166
- 4.11.1 Focus mechanisms/166
- 4.11.2 Zoom mechanisms/174
- 4.12 Sealing and Purging Lens Assemblies/177
- 5. Mounting Optical Windows, Filters, Shells, and Domes/181
- 5.1 Simple Window Mountings/181
- 5.2 Mounting "Special" Windows/185
- 5.3 Conformal Windows/188
- 5.4 Windows Subject to Pressure Differential/192
- 5.4.1 Survival/192
- 5.4.2 Optical effects/197
- 5.5 Filter Mountings/197
- 5.6 Mounting Shells and Domes/201
- 6. Prism Design/207
- 6.1 Principal functions/207
- 6.2 Geometric Considerations/207
- 6.2.1 Refraction and reflection/207
- 6.2.2 Total internal reflection/213
- 6.3 Aberration Contributions of Prisms/215
- 6.4 Typical Prism Configurations/215
- 6.4.1 Right-angle prism/216
- 6.4.2 Beamsplitter (or beamcombiner) cube prism/216
- 6.4.3 Amici prism/216
- 6.4.4 Porro prism/219
- 6.4.5 Porro erecting system/219
- 6.4.6 Abbe version of the Porro prism/221
- 6.4.7 Abbe erecting system/221
- 6.4.8 Rhomboid prism/222
- 6.4.9 Dove prism/222
- 6.4.10 Double dove prism/224
- 6.4.11 Reversion, Abbe type A, Abbe type B prisms/226
- 6.4.12 Pechan prism/227
- 6.4.13 Penta prism/228
- 6.4.14 Roof penta prism/228
- 6.4.15 Amici/penta erecting system/230
- 6.4.16 Delta prism/231
- 6.4.17 Schmidt roof prism/234
- 6.4.18 45-deg Bauernfeind prism/234
- 6.4.19 Frankford arsenal prisms Nos. 1 and 2/235
- 6.4.20 Leman prism/235
- 6.4.21 Internally-reflecting axicon prism/236
- 6.4.22 Cube corner prism/237
- 6.4.23 Ocular prism for a coincidence rangefinder/241
- 6.4.24 Biocular prism system/242
- 6.4.25 Dispersing prisms/243
- 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/250
- 6.4.30 Anamorphic prism systems/266
- 7. Techniques for Mounting Prisms/255
- 7.1 Kinematic Mountings/255
- 7.2 Semikinematic Mountings/256
- 7.3 The Use of Pads on Cantilevered and Straddling Springs/266
- 7.4 Mechanically Clamped Nonkinematic Mountings/272
- 7.5 Bonded Prism Mountings/276
- 7.5.1 General considerations/276
- 7.5.2 Examples of bonded prisms/277
- 7.5.3 Double-sided prism support techniques/280
- 7.6 Flexure Mountings for Prisms/286
- 8. Mirror Design/291
- 8.1 General Considerations/291
- 8.2 Image Orientation/292
- 8.3 First- and Second-Surface Mirrors/296
- 8.4 Ghost Image Formation with Second-Surface Mirrors/298
- 8.5 Approximation of Mirror Aperture/302
- 8.6 Weight Reduction Techniques/303
- 8.6.1 Contoured-back configurations/305
- 8.6.2 Cast ribbed substrate configurations/313
- 8.6.3 Built-up structural configurations/317
- 18.104.22.168 Egg crate construction/317
- 22.214.171.124 Monolithic construction/319
- 126.96.36.199 Frit bonded construction/321
- 188.8.131.52 Hextek construction/322
- 184.108.40.206 Machined core construction/324
- 220.127.116.11 Foam Core construction/327
- 18.104.22.168 Internally machined mirror construction/331
- 8.7 Thin Facesheet Configurations/333
- 8.8 Metallic Mirrors/334
- 8.9 Metallic Foam Core Mirrors/343
- 8.10 Pellicles/345
- 9. Techniques for Mounting Smaller Nonmetallic Mirrors/353
- 9.1 Mechanically Clamped Mirror Mountings/353
- 9.2 Bonded Mirror Mountings/365
- 9.3 Compound Mirror Mountings/369
- 9.4 Flexure Mountings for Smaller Mirrors/379
- 9.5 Central and Zonal Mountings/388
- 9.6 Gravitational Effects on Smaller Mirrors/390
- 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/414
- 10.4 Plating of Metal Mirrors/422
- 10.5 Interfacing Metallic Mirrors for Assembly and Alignment/424
- 11. Techniques for Mounting Larger Nonmetallic Mirrors/431
- 11.1 Mounts for Axis Horizontal Applications/431
- 11.1.1 V-mounts/432
- 11.1.2 Multipoint edge supports/439
- 11.1.3 The "ideal" radial mount/441
- 11.1.4 Strap and roller chain supports/444
- 11.1.6 Mercury tube supports/450
- 11.2 Mounts for Axis Vertical Applications/451
- 11.2.1 General considerations/451
- 11.2.2 Air bag axial supports/451
- 11.2.3 Metrology mounts/455
- 11.3 Mounts for Axis Variable Applications/464
- 11.3.1 Counterweighted lever type mountings/464
- 11.3.2 Hindle mounts for large mirrors/469
- 11.3.3 Pneumatic and hydraulic mountings/482
- 11.4 Supports for Large, Space Borne Mirrors/499
- 11.4.1 The Hubble Space Telescope/499
- 11.4.2 The Chandra X-Ray Telescope/503
- References 505
- 12. Aligning Refracting, Reflecting and Catadioptric Systems/506
- 12.1 Aligning the Individual Lens/509
- 12.1.1 Simple techniques for aligning a lens/510
- 12.1.2 Rotating spindle techniques/512
- 12.1 3 Techniques using a "Point Source Microscope"/518
- 12.2 Aligning Multiple Lens Assemblies/520
- 12.2 1 Using an alignment telescope/521
- 12.2.2 Aligning microscope objectives/524
- 12.2.3 Aligning multiple lenses on a precision spindle/531
- 12.2.4 Aberration compensation at final assembly/533
- 12.2.5 Selecting aberration compensators/541
- 12.3 Aligning Reflecting Systems/543
- 12.3.1 Aligning a simple Newtonian telescope/543
- 12.3.2 Aligning a simple Cassegrain telescope/545
- 12.3.3 Aligning a simple Schmidt camera/547
- 13. Estimation of Mounting Stresses in Optical Components/551
- 13.1 General Considerations/551
- 13.2 Statistical Prediction of Optic Failure/552
- 13.3 Rule-of-Thumb Stress Tolerances/557
- 13.4 Stress Generation at Point, Line, and Area Contacts/559
- 13.5 Peak Contact Stress in an Annular Interface/567
- 13.5.1 Stress with a sharp corner interface/568
- 13.5.2 Stress with a tangential interface/569
- 13.5.3 Stress with a toroidal interface/571
- 13.5.4 Stress with a spherical interface/572
- 13.5.5 Stress with a flat bevel interface/572
- 13.5.6 Parametric comparisons of interface types/572
- 13.6 Bending Effects in Asymmetrically Clamped Optics/576
- 13.6.1 Bending stress in the optic/576
- 13.6.2 Change in surface sagittal depth of a bent optic/578
- 14. Effects of Temperature Changes/581
- 14.1 Athermalization Techniques for Reflective Systems/581
- 14.1.1 Same material designs/581
- 14.1.2 Metering rods and trusses/582
- 14.2 Athermalization Techniques for Refractive Systems/585
- 14.2.1 Passive compensation /587
- 14.2.2 Active compensation/592
- 14.3 Effects of Temperature Change on Axial Preload/598
- 14.3.1 Axial dimension changes/598
- 14.3.2 Quantifying K3/600
- 22.214.171.124 Considering bulk effects only/601
- 126.96.36.199 Considering other contributing factors/604
- 14.3.3 Advantages of athermalization and compliance/606
- 14.4 Radial Effects in Rim Contact Optics/614
- 14.4.1 Radial stress in the optic/614
- 14.4.2 Tangential (hoop) stress in the mount wall/614
- 14.4.3 Growth of radial clearance at high temperatures/615
- 14.5 Effects of Temperature Gradients/617
- 14.5 1 Radial gradients/621
- 14.5.2 Axial gradients/623
- 14.6 Thermally Induced Stresses in Bonded Optics/624
- 15. Hardware Examples/629
- 15.1 Infrared Sensor Lens Assembly/629
- 15.2 A Family of Commercial Mid-Infrared Lenses/630
- 15.3 Using SPDT to Mount and Align Poker Chip Subassemblies/631
- 15.4 A Dual Field IR Tracker Assembly/636
- 15.5 A Dual Field IR Camera Lens Assembly/639
- 15.6 A Passively Stabilized 10:1 Zoom Lens Objective/641
- 15.7 A 90 mm, f/2 Projection Lens Assembly/641
- 15.8 A Solid Catadioptric Lens Assembly/643
- 15.9 An All Aluminum Catadioptric Lens Assembly/645
- 15.10 A Catadioptric Star Mapping Objective Assembly/646
- 15.11 A 150 in., f/10 Catadioptric Camera Objective/650
- 15.12 The Camera Assembly for the DEIMOS Spectrograph/654
- 15.13 Mountings for Prisms in a Military Articulated Telescope/657
- 15.14 A Modular Porro Prism Erecting System for a Binocular/661
- 15.15 Mounting Large Dispersing Prisms in a Spectrograph Imager/665
- 15.16 Gratings for the FUSE Spectrograph /669
- 15.17 The Spitzer Space Telescope/673
- 15.18 A Modular Dual Collimator/677
- Appendix A Unit Conversion Factors/685
- Appendix B Mechanical Properties of Materials/687
- Table B1 Optomechanical properties of 50 Schott optical glasses /688
- Table B2 Optomechanical properties of radiation resistant Schott glasses/691
- Table B3 Selected optomechanical characteristics of optical plastics/692
- Table B4 Optomechanical properties of selected alkali halides and alkaline earth halides/694
- Table B5 Optomechanical properties of selected IR-transmitting glasses and other oxides/693
- Table B6 Optomechanical properties of diamond and selected IR-transmitting semiconductor materials/696
- Table B7 Mechanical properties of selected IR-transmitting chalcogenide materials/697
- Table B8a Mechanical properties of selected nonmetallic mirror substrate materials/698
- Table B8b Mechanical properties of selected metallic and composite mirror substrate materials/699
- Table B9 Comparison of material figures of merit for mirror design/700
- Table B10a Characteristics of aluminum alloys used in mirrors/701
- Table B10b Common temper conditions for aluminum alloys/702
- Table B10c Characteristics of aluminum matrix composites/703
- Table B10d Beryllium grades and some of their properties/704
- Table B10e Characteristics of major silicon carbide types/705
- Table B11 Techniques for machining, finishing, and coating materials for optical applications/706
- Table B12 Mechanical properties of selected metals used for mechanical parts in optical instruments/708
- Table B13 Typical characteristics of optical cements/711
- Table B14 Typical characteristics of representative structural Adhesives/712
- Table B15 Typical physical characteristics of representative elastomeric sealants/715
- Table B16 Fracture strength SF of infrared materials/717
- Appendix C Torque-Preload Relationship for a Threaded Retaining Ring/719
- Appendix D Summary of Methods for Testing Optical Components and Optical Instruments Under Adverse Environmental Conditions/721
PREFACE TO THE SECOND EDITION
This second edition of Mounting Optics in Optical Instruments updates and expands the prior discussions of pertinent technologies for interfacing optics with their mechanical surrounds in optical instruments. The general format of the first edition is maintained, but some topics are repositioned to fit better into the contexts of the various chapters. For example, a section of a chapter in the previous edition dealing with the design, fabrication, and mounting of metallic mirrors has been expanded and elevated to a separate chapter and a new chapter on aligning single and multiple lenses and reflecting optical systems has been added.
The entire text of the book has been rewritten to help clarify many technical details, to correct some misleading statements in the earlier version, and to add new material. All equations that carry over from the first edition have been checked and a few corrections made. New equations have been added as appropriate to enhance the technical content of the new edition. As Jacobs1 once said: "it is not possible to make drawings that clearly show the functioning of optical instruments without exaggeration of some details. In some cases, these exaggerations lead to technical absurdities." I also believe that, in a work of this sort, the primary purpose of a drawing is to instruct rather than to be an exact representation of an original. For this reason, I have not hesitated to exaggerate drawing details whenever appropriate for the sake of clarity. The total number of figures is increased by more than one-third over the prior edition to help the reader visualize details in the designs being discussed.
Specific major improvements in this edition are as follows:
- In Chapter 1 (Introduction), useful information regarding stress-induced birefringence and radiation effects in glasses has been added. Discussions of environmental effects on optics and on optical instruments are expanded. A basic procedure for tolerancing optics is outlined and selected effects of tightening tolerances for typical component parameters on costs of those components are indicated. Key techniques for making mechanical parts for optical instruments are summarized. The number of pages is doubled and the number of figures has grown four-fold.
- In Chapter 2 (Optic/Mount Interface), the important topic of how to center lenses in their mounts is significantly expanded. Various techniques that can be used to measure lens centration errors are explained. Basic techniques for sealing instruments statically and dynamically are illustrated. The number of pages and the number of figures are each nearly doubled.
- In Chapter 3 (Mounting Single Lenses), a new method is suggested for estimating the appropriate axial preload on lenses when those lenses are not otherwise constrained radially and are exposed to transverse accelerations. Techniques for estimating the weights and the locations of centers of gravity for lenses of different configurations are outlined and illustrated with examples. Methods for determining the appropriate annular thicknesses in athermal elastomeric ring mountings for circular optics are outlined and the significance of the elastomer's Poisson's ratio in these calculations is explained. The size of the chapter and the number of figures have remained essentially constant, but the number of equations has increased by one-third.
- Chapter 4 (Mounting Multiple Lenses) now includes descriptions of hardware designs for a large astrographic objective, assemblies featuring lenses mounted in poker-chip fashion, and optomechanical designs for high acceleration applications. Details are added regarding photographic lenses, all-plastic lens assemblies, and mechanisms used to focus lenses and to change (i.e., zoom) their focal lengths. Page and figure counts have increased by about one-third.
- In Chapter 5 (Mounting Windows, Filters, Shells and Domes) we now include a brief summary of new techniques for reducing aerodynamic problems associated with use of domes on high-speed aircraft and missile applications by contouring the dome into the adjacent airframe skin. A design for a fail-safe dual-pane window suitable for photographic use in a commercial aircraft also is summarized. The size of this chapter is about the same as that in the prior edition.
- Chapter 6 (Prism Design) once again shows designs for various prisms and includes some types not previously mentioned. The page count and the number of figures have increased by approximately one-fourth.
- Chapter 7 (Mounting Prisms) remains basically unchanged from the corresponding chapter in the first edition.
- Chapter 8 (Mirror Design) now includes additional information on image orientation control, the layout of simple two-mirror periscopes, silicon and metallic foam-core mirrors, the adaptive secondary mirrors for the Large Binocular Telescopes, the beryllium secondary for the Very Large Telescope, and the James Webb Space Telescope segmented primary. Page count, the number of figures, and the number of equations have all increased by about one-half.
- In Chapter 9 (Mounting Smaller Mirrors), we have added descriptions of mountings for small circular mirrors with multiple discrete bond joints to structure on the mirror's back surface and on its rim. Equations given previously for design of a 9-point Hindle mount for axial support of circular solid mirrors have been augmented to allow the nominal design of an 18-point mount. Page and figure counts are essentially unchanged, as is the number of equations presented.
- Chapter 10 (Mounting Metallic Mirrors) is expanded significantly as compared to the treatment of this subject as a section of Chapter 9 in the first edition. A much more detailed treatment of the use of single point diamond turning (SPDT) fabrication techniques is now included. Several additional examples of hardware designs are described. Many of these designs feature flexures that isolate the optical surface from forces delivered by the mounting. Published developments of platings for metallic mirror surfaces are summarized briefly and some effects of key types on mirror performance under temperature changes are indicated. Subject matter coverage, as measured by either page count or the number of figures, has tripled.
- Chapter 11 (Mounting Larger Mirrors) has been reformatted to group designs into axis-horizontal, axis-vertical, axis-variable, and space applications. Many of the included designs depict key developments that have allowed significant performance enhancement and size growth in astronomical telescope systems. The page count and number of figures for this important topic are both increased by about one-third.
- Chapter 12 (Aligning Lens and Mirror Systems) is a new chapter amplifying the material previously in brief sections of Chapters 3 and 4. New topics include the use of a modified alignment telescope and of a Point Source Microscope* to align individual and multiple lenses. Also added are descriptions of an extremely precise method for aligning very high performance microscope objectives and of a method for determining which components to adjust during final assembly to optimize performance of complex systems. Page count and the number of figures are increased three-fold and four-fold respectively.
- In Chapter 13 (Estimating Mounting Stresses), research leading to the now generally accepted rule-of-thumb limit, or tolerance, of 1000 lb/in.2 (6.89 MPa) for tensile stress created in a typical glass optic by applied mounting force is summarized. The effects of surface flaws, such as scratches or subsurface cracks, on this tolerance also are indicated. If the worst-case condition of the surfaces on the optic is known or can be estimated, the useful lifetime of the optic can be predicted statistically. As in the prior edition, computational methods, many utilizing equations developed by Roark2 for peak compressive stresses generated in the contacting optical and mechanical members, are applied to various types of mechanical interfaces with optical components. These computations are extended in this edition by utilizing theory from Timoshenko and Goodier3 to quantify the corresponding tensile stresses in the optic. We then show how the suitability of a given optomechanical mounting design can be determined by comparison of these stress levels with the rule-of-thumb tolerance. The scope of the subject matter treatment in this edition (measured by page count and numbers of figures and equations) is essentially the same as that in the prior edition.
- In Chapter 14 (Temperature Effects), we have extended the previously published discussion of how temperature changes affect axial and transverse mounting forces. Several pertinent factors not considered in the first edition are defined. Some, but not all, of these can be quantified using available theory. In the absence of a complete methodology for quantifying temperature effects on any given hardware design, we now advocate the provision of a controlled amount of compliance in the mechanical design of that hardware so as to minimize these temperature effects. Several typical practical design examples are considered. The page count and the number of figures in this chapter have grown by about one-half.
- Chapter 15 (Hardware Examples) continues the practice established in the first edition of discussing the optomechanical designs of selected hardware items to illustrate many of the topics considered in the text. In this edition, twenty-one such examples are given while, in the prior edition, there were thirty. This, however, does not represent a reduction in the book's total technical scope because five new examples have been added to this chapter and fifteen of the previous examples are now discussed in the context of the pertinent technology in earlier chapters.
- Appendices A and B to the new edition provide unit conversion factors and numerous updated values for mechanical properties and other characteristics of key materials used in optical instrument design. As before, Appendix C derives the torque-preload relationship for a threaded retaining ring. A summary of methods for environmental testing of optical components and instruments is now provided as Appendix D.
- Once again, a CD-ROM is provided with this book so the reader can access Microsoft Excel worksheets that use the 679 equations given in the text to solve the 100 numerical examples intermingled with the technical discussions as well to design 24 types of prisms and prism assemblies that are described here. The worksheets are configured so new input data can be inserted to create new designs or to conduct parametric analyses.
I acknowledge the contributions of the many friends and associates who provided new information to this book or helped me clarify confusing matters previously presented. In particular, I thank Daniel Vukobratovich and Alson Hatheway who have helped me understand many pertinent intricacies of optomechanical design. On the editorial side, I sincerely thank Merry Schnell who copy-edited the manuscript, resolved editorial issues and kept the production schedule moving at SPIE Press. While all contributors tried valiantly to help me present the technical material clearly and correctly, I accept total responsibility for any errors that remain. I sincerely hope this book proves useful to all its readers.
1. Jacobs, D.H., Fundamentals of Optical Engineering, McGraw-Hill, New York, 1943.
2. Roark, R.J., Formulas for Stress and Strain, 3rd ed., McGraw-Hill, New York, 1954.
3. Timoshenko, S.P. & Goodier, J.N., Theory of Elasticity, 3rd ed., McGraw-Hill, New York, 1970.
Paul R. Yoder, Jr.
PREFACE TO THE FIRST EDITION
This work is intended to provide practitioners in the fields of optical engineering and optomechanical design with a comprehensive understanding of the principal ways in which optical components such as lenses, windows, filters, shells, domes, prisms, and mirrors of all sizes typically are mounted in optical instruments. It also addresses the advantages and disadvantages of various mounting arrangements and provides some analytical tools that can be used to evaluate and compare different optomechanical designs. The presentation includes the theoretical background for some of these tools and cites the sources for the most of the equations listed. Each section contains an illustrated discussion of the technology involved and, wherever feasible, one or more worked-out practical examples.
Two chapters deal with the fundamentals of design for optical components. These are Chapters 6 on prism design and Chapter 8 on mirror design. These topics are considered appropriate, and indeed necessary, as background for considering how best to mount these very important types of optics.
The book is based, in part, on short courses entitled Precision Optical Component Mounting Techniques and Principles for Mounting Optical Components offered by SPIEThe International Society for Optical Engineeringthat I have had the privilege of teaching over a period of several years. Many, but not all, of the techniques for mounting optics covered here have been presented previously in the tutorial texts Mounting Lenses in Optical Instruments1 and Design and Mounting of Prisms and Small Mirrors in Optical Instruments2 as well as in my earlier reference book Opto-Mechanical Systems Design.3 Several recent designs for mounting optics are included here to broaden the coverage and to bring the material more nearly up to date. Coverage of window-type optics and of large mirrors has been expanded over the previous works.
Wherever possible, numerical values given in this book are expressed in both the metric or Système International (SI) units and the units in customary use in the United States and Canada. The latter are abbreviated in this book as "USC" as in some recent textbooks. Examples taken directly from the literature may be expressed only in the system used by the original author. Units can be easily changed from one system to the other through use of the conversion factors given in Appendix A.
All the designs discussed here are drawn from the literature, my own experiences in optical instrument design and development, and the work of colleagues. I acknowledge with my deepest thanks the contributions of others, including the many participants in the above-mentioned SPIE short courses and the readers of my previous books, and sincerely hope that I have accurately recorded and explained the information they have given to me. I acknowledge and thank Donald O'Shea and Daniel Vukobratovich, who reviewed the manuscript for this book and suggested many improvements. I also thank Mary Haas, Rick Hermann, and Sharon Streams for their outstanding copy editing and editorial suggestions. While these people helped me to present the material clearly and correctly, I am solely responsible for and deeply regret any errors that remain. One particularly annoying error is that the headings on even numbered pages differ from the actual title of the book!
The mounting stress theories discussed in Chapter 11 are considered to be conservative approximations. They are intended to indicate whether a given design can be judged to be adequate from a stress viewpoint or if it should be analyzed by more elaborate finite-element and/or statistical techniques. The same is true of the treatment of temperature effects on axial preload in Chapter 12. These topics would benefit greatly from further investigation, refinement, and (it is hoped) verification by other workers based on more precise computational methods, such as finite-element analysis. I would welcome comments, corrections, and suggestions for improvements in the presentations of these topics and/or in any other portion of this book.
A feature included with this book is a CD-ROM containing two Microsoft Excel worksheets that allow convenient use of the many equations given in this text to solve typical optomechanical interface design and analysis problems. Some of these equations are relatively complex, so the worksheets have been developed to facilitate equation use and to reduce the chance of improper parameter application. The 102 files included in each worksheet correspond to designs and/or numerical examples worked out in the text. Input values pertaining specifically to those examples are listed. The two worksheets on the disk are different versions of the same program. In Version 1, data inputs are in U.S. Customary units while in Version 2 inputs are in metric units. In both cases, all data are presented in both sets of units. A table of files (with hyperlinks) is provided in each worksheet to assist in finding the proper file for a specific computation. The examples in the text are cross-referenced to the applicable worksheet files. Custom solutions to problems similar to the examples in the text can be obtained by revising the input data in the file as appropriate for the case to be evaluated. The program will then automatically solve the problem using those inputs and the appropriate equations from the text. This tool should be especially useful when parametric analysis of variations of key parameters is needed to obtain an optimum design.
I sincerely wish for the users of this book and of the CD-ROM a deepening understanding of the technologies discussed and success in the application of the concepts, designs, and analysis techniques presented here.
1. Yoder, P.R., Jr., Mounting Lenses in Optical Instruments, TT21, SPIE Press, Bellingham, 1995.
2. Yoder, P.R., Jr., Design and Mounting of Prisms and Small Mirrors in Optical Instruments, TT32, SPIE Press, Bellingham, 1998.
3. Yoder, P.R., Jr., Opto-Mechanical Systems Design, 2nd ed., Marcel Dekker, New York, 1993.
Paul R. Yoder, Jr.