Abstract
This section contains the introduction, table of contents, and list of symbols and acronyms.

Library of Congress Cataloging-in-Publication Data

Schwertz, Katie M.

Field guide to optomechanical design and analysis / Katie M. Schwertz, Jim H. Burge

p. cm. – (The field guide series)

Includes bibliographical references and index.

ISBN 978-0-8194-9161-9

1. Optical instruments--Design and construction--Handbooks, manuals, etc. 2. Optomechanics--Handbooks, manuals, etc. I. Burge, James H. II. Title.

TS513.S385 2012

681.4--dc23

2012013233

Published by

SPIE

P.O. Box 10

Bellingham, Washington 98227-0010 USA

Phone: +1.360.676.3290

Fax: +1.360.647.1445

Email: books@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. For the latest updates about this title, please visit the book's page on our website.

SPIE Terms of Use: This SPIE eBook is DRM-free for your convenience. You may install this eBook on any device you own, but not post it publicly or transmit it to others. SPIE eBooks are for personal use only. For details, see the SPIE Terms of Use. To order a print version, visit SPIE.

Printed in the United States of America.

First printing

cop.jpg

Introduction to the Series

Welcome 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. A significant 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

College of Optical Sciences

The University of Arizona

Field Guide to Optomechanical Design and Analysis

Optomechanics is a field of mechanics that addresses the specific design challenges associated with optical systems. This Field Guide describes how to mount optical components, as well as how to analyze a given design. It is intended for practicing optical and mechanical engineers whose work requires knowledge in both optics and mechanics.

Throughout the text, we describe typical mounting approaches for lenses, mirrors, prisms, and windows; standard hardware and the types of adjustments and stages available to the practicing engineer are also included. Common issues involved with mounting optical components are discussed, including stress, glass strength, thermal effects, vibration, and errors due to motion. A useful collection of material properties for glasses, metals, and adhesives, as well as guidelines for tolerancing optics and machined parts can be found throughout the book.

The structure of the book follows Jim Burge’s optomechanics course curriculum at the University of Arizona. We offer our thanks to all those who helped with the book’s development and who provided content and input. Much of the subject matter and many of the designs are derived from the work of Paul Yoder and Dan Vukobratovich; their feedback is greatly appreciated.

Katie Schwertz

Edmund Optics®

Jim Burge

College of Optical SciencesUniversity of Arizona

Table of Contents

List of Symbols and Acronyms ix

Image Motion and Orientation 1

Optical Effects of Mechanical Motion 1

Lens and Mirror Motion 2

Plane Parallel Plate 3

General Image-Motion Equations 4

Image Motion Example 5

Rigid Body Rotation 6

Quantifying Pointing Error 7

Image Orientation 8

Mirror Matrices 10

Mirror Rotation Matrices 12

Cone Intersecting a Plane 13

Stress, Strain, and Material Strength 14

Stress and Strain 14

Strain-vs-Stress Curve 16

Safety Factor 17

Glass Strength 18

Stress Birefringence 20

Precision Positioning 22

Kinematic Constraint 22

Example Constraints and Degrees of Freedom 23

Semi-Kinematic Design 24

Issues with Point Contacts 25

Precision Motion 27

Stage Terminology 28

Linear Stages 29

Rotation and Tilt Stages 30

Errors in Stage Motion 31

Precision Fastening and Adjustments 32

Standard Hardware 32

Example Screws 33

Fastener Strength 34

Tightening Torque 36

Adjusters 37

Differential Screws and Shims 38

Liquid Pinning 39

Electronic Drivers 40

Flexures 41

Stiffness Relations for Single-Strip Flexures 42

Parallel Leaf Strip Flexures 43

Stiffness Relations for Parallel Leaf Strip Flexures 44

Notch Hinge Flexures 45

Adhesives 46

Adhesive Properties 47

Adhesive Thickness and Shape Factor 48

Thermal Stress 49

Choice of Bond Size and Thickness 50

Mounting of Optical Components 51

Lens Mounts: Off the Shelf 51

Lens Mounting: Custom 53

Calculating Torque and Clearance 54

Potting a Lens with Adhesive 55

Clamped Flange Mount 56

Lens Barrel Assemblies 57

Lens Barrel Assembly Types 58

Surface–Contact Interfaces 60

Prism Types 62

Image-Rotation Prisms 64

Image-Erection Prisms 65

Prism and Beamsplitter Mounting 66

Thin-Wedge Systems 68

Window Mounting 69

Domes 72

Dome Strength 73

Small-Mirror Mounts: Off the Shelf 74

Small-Mirror Mounts: Adhesives and Clamping 75

Small-Mirror Mounts: Tangent Flexure and Hub 76

Mirror Substrates 77

Mirror Substrate Examples 79

Large-Mirror Mounting: Lateral Supports 80

Large-Mirror Mounting: Point Supports 81

Large-Mirror Mounting: Active Supports 82

Self-Weight Deflection: General 83

Self-Weight Deflection: Thin Plates 84

Self-Weight Deflection: Parametric Model 85

Lightweighting Mirrors 86

Flexural Rigidity of Lightweighted Mirrors 88

Design Considerations and Analysis 89

RMS, P–V, and Slope Specifications 89

Finite Element Analysis 90

Vibration 94

Damping Factor 95

Isolation 96

System Acceleration and Displacement 97

Thermal Effects 98

Heat Flow 100

Air Index of Refraction 102

Athermalization 103

Passive Athermalization 104

Active Athermalization 105

Determining Thermally Induced Stress 106

Alignment 107

Optical and Mechanical Axis of a Lens 108

Alignment Tools 109

Tolerancing 110

Geometric Dimensioning and Tolerancing 110

GD&T Terminology 111

GD&T Symbology 112

ISO 10110 Standard 113

Appendices 114

Tolerance Guides 114

Clean-Room Classifications 117

Shipping Environments: Vibration 119

Shipping Environments: Drop Heights 120

Unit Conversions 121

Cost and Performance Tradeoffs for Linear Stages 122

Torque Charts 125

Adhesive Properties 127

Glass Properties 130

Metal Properties 134

Equation Summary 136

Glossary 141

References 144

Biography 148

List of Symbols and Acronyms

%TMC

Percent total mass lost

%CVCM

Percent collected volatile condensable material

a

Acceleration

A

Area

CAD

Computer-aided design

COTS

Commercial off-the-shelf

Cp

Specific heat capacity

CTE

Coefficient of thermal expansion

CVD

Chemical vapor deposition

d

Displacement

d

Distance

D

Diameter

D

Thermal diffusivity

D

flexural rigidity

E

Young’s modulus

f

Focal length

F

Force, load

f0

Natural frequency (Hz)

FEA

Finite element analysis

FEM

Finite element method

g

Gravity (9.8 m/s2)

G

Shear modulus

GD&T

Geometric dimensioning and tolerancing

h

Height, thickness

IR

Infrared

k

Stiffness

K

Bulk modulus

Kc

Fracture toughness

Ks

Stress optic coefficient

l

Length

L

Length

LMC

Least material condition

LOS

Line of sight

m

Magnification

m

Mass

MMC

Maximum material condition

MoS

Margin of safety

n

Index of refraction

NA

Numerical aperture

NIST

National Institute of Standards and Technology

OPD

Optical path difference

P

Preload

p

Pressure

PEL

Precision elastic limit

ppm

Parts per million (1×10−6)

PSD

Power spectral density

psi

Pounds per square inch

P–V

Peak to valley

Q

Heat flux

r

Radius (distance, i.e., 0.5D)

R

Radius (of curvature)

RSS

Root sum square

RTV

Room-temperature vulcanization

t

Thickness

T

Temperature

UTS

Unified thread standard

UV

Ultraviolet

x, y, z

Distances in the x, y, or z axis

α

Coefficient of thermal expansion

β

Therm-optic coefficient (coefficient of thermal defocus)

γ

Shear strain

δ

Deflection

ΔT

Change in temperature

Δx

Change in lateral distance (x axis)

Δy

Change in lateral distance (y axis)

Δz

Change in axial distance

ε

Emissivity

ε

Strain

ζ

Damping factor

θ

Angle

λ

Thermal conductivity

ν

Poisson ratio

ρ

Density

σ

Stress

σys

Yield strength

τ

Shear stress

ω

Frequency

ω0

Natural frequency (rad/s)

TOPIC
9 PAGES

SHARE
Back to Top