Designing Optics Using Code V

347 Pages·2018·52.316 MB·English

by  Donald C. O'Shea, Julie L. Bentley

Designing Optics
Using CODE V®
Donald C. O'Shea
Julie L. Bentley
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Designing Optics
Using CODE V®
Donald C. O'Shea
Julie L. Bentley
SPIE PRESS
Bellingham, Washington USA
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Library of Congress Cataloging-in-Publication Data
Names: O’Shea, Donald C., author | Bentley, Julie L., author.
Title: Designing optics using CODE V / Donald C. O’Shea and Julie L. Bentley.
Description: Bellingham, Washington, USA : SPIE Press, [2018] | Includes
bibliographical references and index.
Identifiers: ISBN 9781510619739 (soft cover) | ISBN 1510619739 (soft cover) | ISBN
9781510619746 (PDF) | ISBN 1510619747 (PDF) | ISBN 9781510619753 (ePub) |
ISBN 1510619755 (ePub) | ISBN 9781510619760 (Kindle) | ISBN 1510619763
(Kindle)
Subjects: LCSH: Optical design.
LC record available at https://lccn.loc.gov/2018025570
Published by
SPIE
P.O. Box 10
Bellingham, Washington 98227-0010 USA
Phone: [phone]
Fax: [phone]
Email: [email protected]
Web: http://spie.org
Copyright © 2018 Society of Photo-Optical Instrumentation Engineers (SPIE)
All rights reserved. No part of this publication may be reproduced or distributed in any
form or by any means without written permission of the publisher.
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.
Printed in the United States of America.
Last updated 23 July 2018
For updates to this book, visit http://spie.org and type “PM292” in the search field.
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For Helen, master gardener and patient wife.
Don O’Shea

For my dad, for showing me that anything can be
accomplished with hard work (and duct tape).
Julie Bentley

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Contents

Preface xiii
Introduction xv

Chapter 1 The Basics 1
1.1 Ray Calculations 2
1.1.1 Law of refraction: Snell’s law 4
1.1.2 Law of reflection 5
1.1.3 The transfer equation 7
1.2 Lenses 9
1.3 Imaging 12
1.4 Types of Images 15
Exercises 16
Answers 17

Chapter 2 Rays and Ray Sketching 19
2.1 Collimation 19
2.2 Thin Lenses 20
2.3 Ray Sketching 22
2.3.1 Finite object distance 24
2.3.2 Object at infinity 24
2.4 Treating Virtual Images 25
2.5 Mirrors 26
2.6 Planar Optics 30
2.7 Multiple Elements 31
2.8 Beyond Two-Lens Systems 33
Answers 33

First Hiatus: Ledgers to Laptops 35
H1.1 Simulations 35
H1.2 Tracing Rays 36

Chapter 3 How to Put a Lens in a Computer 39
3.1 System Data 41
3.2 Prescription Data 41
3.3 Entering a Single Lens Using Commands 45
3.4 Entering a Single Lens Using the Lens Design Manager 47
3.5 Checking the Lens 51
3.5.1 First-order properties 52
3.5.2 Reduction ratio 54
3.6 Angle Solves 55
3.7 Entering Mirrors 60
vii
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viii Contents
3.8 Design Forms 63
Exercises 63
Answers 66

Chapter 4 To First Order… 71
4.1 Principal Surfaces and Planes 71
4.2 What Does This Get You 74
4.3 Cardinal Points of Lenses and Mirrors 77
4.4 Immersed Systems 79
4.4.1 Nodal points for immersed systems 82
4.4.2 The human eye 84
4.5 A Concluding Remark 87
Exercises 87
Answers 88
Appendix 89

Chapter 5 Stop and Pupils and Windows, Oh My! 91
5.1 Fields 91
5.2 Special Rays 94
5.2.1 Meridional or tangential rays 94
5.2.2 Sagittal rays 95
5.2.3 Skew rays 95
5.2.4 Axial rays 96
5.2.5 Ray for objects at infinity 96
5.2.6 Reference rays 97
5.3 The Aperture Stop and Marginal Rays 97
5.4 Chief Rays and Pupils of a Lens 104
5.5 The Field Stop and its Windows 107
5.6 Pupil and Field Specifications 107
5.6.1 Field of view 108
5.6.2 f-number and numerical aperture 110
5.7 Vignetting 112
5.8 A Final Comment 119
Exercises 119
Answers 120
Appendix 122

Second Hiatus: Rays and Waves 123
H2.1 Rayleigh Criterion 123
H2.2 The Pinhole Camera 125

Chapter 6 Spherical Aberration 127
6.1 Propagating Real Rays 127
6.2 Third-Order Aberrations 128
6.3 On-Axis Ray Errors for a Singlet Lens 130
6.4 Displaying Spherical Aberration 131
6.5 Transverse Ray Plots 133
6.6 Seidel Aberrations 136
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Contents ix
6.7 Lens Bending 138
6.8 Going Off-Axis 142
Exercises 143
Answers 144

Chapter 7 Coma and Astigmatism 147
7.1 Coma 147
7.1.1 Lens modules 149
7.1.2 Coma and lens bending 153
7.2 Aplanatic Lenses 154
7.3 Astigmatism 155
Exercises 158
Answers 158

Chapter 8 Aberrations of the Image Surface 161
8.1 Field Curves 161
8.2 Petzval Curvature 164
8.3 Field Curvature and Third-Order Coefficients 166
8.4 An Astigmatic Lens 169
8.5 Distortion 172
Answers 176

Chapter 9 Chromatic Aberration 179
9.1 Refraction and Dispersion 179
9.2 Longitudinal Chromatic Aberration 183
9.3 Correcting Longitudinal Chromatic Aberration 189
9.4 An Example 191
9.5 Secondary Color and Superchromatism 194
9.6 Lateral Color 197
Answers 201
Appendix 202

Chapter 10 Reducing Aberrations 203
10.1 Defocus 203
10.2 Reducing Spherical Aberration 207
10.3 Reducing Coma 211
10.3.1 Stop shifting 211
10.3.2 Flipping a lens 215
10.4 Reducing Distortion 217
10.5 Reducing Field Curvature 222
10.5.1 Correcting astigmatism 222
10.5.2 Correcting Petzval 225
Exercises 234
Explorations 234
Answers 237

Chapter 11 Analyzing the Performance of a Lens 239
11.1 Sensors 239
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x Contents
11.2 Spot Diagrams 240
11.3 Point Spread Function 243
11.4 Image Simulation 247
11.5 Modulation Transfer Functions 254
Explorations 257

Chapter 12 Designing a Lens 259
12.1 Defining the Problem 259
12.2 Specifying the System 260
12.3 Step 0: The Initial Assessment 261
12.4 Step 1: Bend the Lens 265
12.5 Step 2: Shift the Stop 268
12.6 Step 3: Add a Lens 271
12.6.1 Fictitious glasses 271
12.6.2 Constructing a doublet 272
12.6.3 Optimizing the doublet 274
12.7 Step 4: Add a Field Flattener 277
12.7.1 Optimizing the design 278
12.7.2 Add more field points 280
12.8 Step 5: Return to Real Glasses 284
12.9 Step 6: Open Up the Lens 289
Explorations 293

Third Hiatus: Building a Lens 295
H3.1 Fabricating a Lens Element 295
H3.2 Mounting the Lens 297
H3.3 Testing the Lens 297

Chapter 13 Tolerancing 299
13.1 Statistical Tolerancing 299
13.1.1 TOR 300
13.1.2 Cumulative probability 301
13.2 Default Tolerances in CODE V 302
13.2.1 Element fabrication errors 302
13.2.1.1 Radius of curvature: DLF and DLR 302
13.2.1.2 Thickness: DLT 302
13.2.1.3 Glass: DLN and DLV 303
12.2.1.4 Wedge: TIR (TRX, TRY) 303
12.2.1.5 Cylinder: IRR (CYN, CYD) 304
13.2.2 Lens assembly errors 304
12.2.2.1 Air space: DLT 305
12.2.2.2 Barrel tilt: BTI (BTX, BTY) 305
12.2.2.3 Element decenter: DIS (DSX, DSY) 306
12.2.2.4 Roll: ROL (RLX, RLY) 306
13.3 Design Example 1: OSDsecureCam2 306
13.3.1 Initial tolerancing with sensitivity mode (TOR; SNS) 308
13.3.2 The cumulative probability plot 311
13.3.3 Adding a compensator 313
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Contents xi
13.3.4 Tightening tolerances 316
13.3.5 The lens drawing 318
13.4 Design Example 2: OSDsecureCam6 319
13.4.1 TOR run with default tolerances 322
13.4.2 Tightening tolerances 324
13.4.3 Interactive tolerancing 326
13.4.4 Inverse sensitivity mode (TOR; INV) 328
13.5 Some Final Comments 331

Index 333

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Preface

The purpose of this text is to show you how to design of an optical system, using
the optical design program, CODE V®. The complete design process (from lens
definition to the description and evaluation of lens errors and onto the
improvement of lens performance) will be developed and illustrated using the
program. The text is organized so that a student will be able to (1) reproduce each
step of the process including the plots for evaluating lens performance and (2)
understand their significance in producing a final design. 
We chose CODE V because it is a well-regarded, full-featured optical
design program that has a command line interface. This text is not a user’s manual
for CODE V. Synopsys has a set of online reference books for that. Rather, the text
starts with a single lens to demonstrate the laws of optics and illustrate the basic
optical errors (aberrations) using CODE V. Then, through a series of examples,
demonstrations, and exercises, you can follow each step in the design process using
the CODE V commands to analyze and optimize the system to meet the required
performance specifications. Once the nominal design meets these specs, you can
determine a set of tolerances that permits a large fraction of them to be
manufactured with an acceptable as-built performance. 
Although it is assumed that readers will follow the examples in the text
and reproduce the results, you are encouraged to use them as jumping off points
for an exploration of the designs. In addition to exercises with answers, we have
added toward the end of the text what we call “Explorations”: open-ended
problems with several possible directions to explore the design space. But this
exploration needn’t be confined to the final chapters. If there is a design feature or
strategy that piques your curiosity and you want to find out what happens when
you make a change in the design, go ahead and explore the consequences. You
can’t break anything. However, remember to save your lens before you begin to
tinker with things.
This text is written for a student to continually interact with CODE V.
Although any commercial software can provide the tools to enter and modify
designs, each program has its own interface and command syntax, and it is not
possible to demonstrate important optical principles with every worthwhile
program in a single text. For those who do not have immediate access to CODE V,
there are two possible ways to use this text. If you’re connected with a college or
university, there are arrangements for students to use CODE V for a modest fee
for a limited time. For those who have access to other design programs, the
operations and data entry may differ, but most of them will contain the same
plotting, evaluation, and optimization functions as CODE V. So, with some
translation, it should be possible to demonstrate the same operations as those used
in this text.  
xiii

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