Geometrical and Visual Optics

382 Pages·2013·3.04 MB·English

by  Steven Schwartz

Geometrical and
Visual Optics
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Geometrical and
Visual Optics
A Clinical Introduction
SECOND EDITION
Steven H. Schwartz, OD, PhD
Professor
Department of Biological and Vision Sciences
College of Optometry
State University of New York
New York, New York
New York Chicago San Francisco Athens London Madrid
Mexico City Milan New Delhi Singapore Sydney Toronto
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Contents
Preface .......................................................................................................................xi
1. Basic Terms and Concepts ..................................................................................1
Sources, Light Rays, and Pencils .......................................................................3
Vergence .............................................................................................................4
Refraction and Snell’s Law .................................................................................7
Summary ..........................................................................................................10
Self-Assessment Problems ...............................................................................13
2. Refraction at Spherical Surfaces ....................................................................15
Converging and Diverging Spherical Surfaces ...............................................15
A Word on Sign Conventions ..........................................................................19
Primary and Secondary Focal Points ...............................................................19
A Very Handy Formula ....................................................................................21
Image Formation by Spherical Surfaces ..........................................................24
Real Images ..................................................................................................24
Virtual Images ..............................................................................................26
Summary ..........................................................................................................27
Self-Assessment Problems ...............................................................................28
3. The Vergence Relationship ..............................................................................29
More on Vergence ............................................................................................29
Linear Sign Convention...................................................................................33
Vergence Relationship .....................................................................................34
Sample Problems ..............................................................................................35
Sample Problem 1: Converging Surface ......................................................36
Sample Problem 2: Diverging Surface ........................................................38
Sample Problem 3: Locating the Object .....................................................40
Sample Problem 4: A Flat (Plane) Refracting Surface ................................41
Summary ..........................................................................................................44
Self-Assessment Problems ...............................................................................45
v
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vi Contents
4. Thin Lenses ......................................................................................................47
Ray Tracing ......................................................................................................49
Vergence Relationship .....................................................................................54
Newton’s Relation ............................................................................................59
Summary ..........................................................................................................60
Self-Assessment Problems ...............................................................................60
5. Optical Systems with Multiple Surfaces .........................................................63
Multiple Thin Lens Systems............................................................................63
Virtual Objects .................................................................................................68
Thick Lenses ....................................................................................................70
Summary ..........................................................................................................75
Self-Assessment Problems ...............................................................................75
6. Thick Lenses .....................................................................................................77
Definitions ........................................................................................................77
Back and Front Vertex Power ..........................................................................79
Equivalent Lenses ............................................................................................81
Equivalent Power .........................................................................................81
Locating the Principal Planes ......................................................................81
Sample Problem ...........................................................................................83
Nodal Points .................................................................................................85
Summary ..........................................................................................................86
Self-Assessment Problems ...............................................................................87
7. Ametropia ........................................................................................................89
Myopia ..............................................................................................................91
Hyperopia .........................................................................................................95
Lens Effectivity ................................................................................................98
Correction of Ametropia with Laser and Surgical Procedures .....................103
Summary ........................................................................................................105
Self-Assessment Problems .............................................................................105
8. Accommodation ............................................................................................107
Vergence Relationship for Accommodation ..................................................109
Accommodation in Ametropia .......................................................................110
Near Point of Accommodation ......................................................................114
Accommodation when Ametropia is Corrected with Spectacles ..................117
Correction of Presbyopia ...............................................................................122
Summary ........................................................................................................124
Self-Assessment Problems .............................................................................124
9. Cylindrical Lenses and the Correction of Astigmatism ................................127
Lens Crosses ...................................................................................................127
Lens Formulae/Prescriptions ........................................................................130
Image Formation: Point Sources ...................................................................133
Image Formation: Extended Sources ............................................................135
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Contents vii
Power in an Oblique Meridian of a Cylindrical Lens ...................................136
Astigmatism: Definitions and Classifications ................................................138
Jackson Crossed-Cylinder Test ......................................................................141
Spherical Equivalency ....................................................................................144
What Does a Person with Astigmatism See? ................................................145
Summary ........................................................................................................146
References ......................................................................................................147
Self-Assessment Problems .............................................................................147
10. Prisms ............................................................................................................149
Thick and Thin Prisms ..................................................................................149
Prism Diopters ...............................................................................................151
Prismatic Effects of Lenses ............................................................................151
Clinical Applications ......................................................................................158
Summary ........................................................................................................162
Reference ........................................................................................................162
Self-Assessment Problems .............................................................................162
11. Depth of Field ................................................................................................165
Blur Circles, Visual Acuity, and Pinholes ......................................................165
Diffraction Caused by Apertures ...................................................................168
Depth of Field and Depth of Focus ...............................................................171
Hyperfocal Distance ......................................................................................176
Summary ........................................................................................................178
Self-Assessment Problems .............................................................................178
12. Magnification and Low Vision Devices ........................................................179
Angular Magnification Produced by Plus Lenses .........................................180
Use of Plus Lenses for Low Vision ................................................................183
Magnifying Lens and Bifocal Add
in Combination ..........................................................................................186
Fixed-Focus Stand Magnifiers ...................................................................187
Effective Magnification ..............................................................................191
Electronic Magnifiers for Near .....................................................................193
Telescopes .......................................................................................................194
Galilean Telescopes ....................................................................................194
Keplerian Telescopes ..................................................................................196
An Alternative Formula to Determine a Telescope’s
Angular Magnification ...............................................................................197
A Convenient Clinical Method to Determine a Telescope’s
Angular Magnification ...............................................................................197
Telescope Use in Ametropia ......................................................................199
Telemicroscopes .........................................................................................201
Summary ........................................................................................................203
Further Reading .............................................................................................204
Self-Assessment Problems .............................................................................204
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viii Contents
13. Retinal Image Size ........................................................................................207
Spectacle Magnification .................................................................................207
Retinal Image Size in Uncorrected Ametropia .............................................210
Retinal Image Size in Corrected Ametropia .................................................211
Summary ........................................................................................................215
Self-Assessment Problems .............................................................................215
14. Reflection .......................................................................................................217
Ray Tracing: Concave, Convex, and Plane Mirrors ......................................217
Concave Mirrors ........................................................................................217
Convex Mirrors ..........................................................................................220
Plane Mirrors .............................................................................................220
Power of Mirrors ............................................................................................221
The Vergence Relationship ...........................................................................225
Reflections and Antireflection Coatings ........................................................231
Purkinje Images ..............................................................................................233
Corneal Topography ......................................................................................237
Summary ........................................................................................................239
Self-Assessment Problems .............................................................................240
15. Aberrations ....................................................................................................241
The Paraxial Assumption and Seidel Aberrations .........................................241
Longitudinal Spherical Aberration ............................................................242
Coma ..........................................................................................................245
Oblique Astigmatism ..................................................................................246
Curvature of Field ......................................................................................249
Distortion ...................................................................................................250
Wavefront Sensing and Adaptive Optics .......................................................250
Measurement of the Eye’s Monochromatic Aberrations ..........................250
Supernormal Vision ....................................................................................253
Imaging the Fundus ...................................................................................256
Chromatic Aberration ....................................................................................257
Dispersive Power and Constringence ........................................................257
Lateral (Transverse) Chromatic Aberration ..............................................258
Longitudinal Chromatic Aberration ..........................................................260
Chromatic Aberration in the Human Eye .................................................261
The Red–Green Refraction Technique .....................................................263
Summary ........................................................................................................264
References ......................................................................................................265
Self-Assessment Problems .............................................................................266
Answers to Self-Assessment Problems ................................................................267
Chapter 1: Basic Terms and Concepts .........................................................267
Chapter 2: Refraction at Spherical Surfaces ................................................268
Chapter 3: The Vergence Relationship .......................................................270
Chapter 4: Thin Lenses ...............................................................................275
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Contents ix
Chapter 5: Optical Systems with Multiple Surfaces ...................................279
Chapter 6: Thick Lenses ..............................................................................284
Chapter 7: Ametropia ..................................................................................290
Chapter 8: Accommodation .........................................................................292
Chapter 9: Cylindrical Lenses and the Correction of Astigmatism ...........298
Chapter 10: Prisms .........................................................................................302
Chapter 11: Depth of Field ............................................................................304
Chapter 12: Magnification and Low Vision Devices ....................................305
Chapter 13: Retinal Image Size .....................................................................308
Chapter 14: Reflection ...................................................................................309
Chapter 15: Aberrations .................................................................................314
Appendix A: Entrance and Exit Pupils of Telescopes ..........................................317
Appendix B: Location of Purkinje Image III ........................................................323
Appendix C: Fluid Lenses .....................................................................................329
Appendix D: Javal’s Rule .....................................................................................335
Appendix E: Derivation of the Paraxial Relationship .........................................337
Appendix F: Correction of Chromatic Aberration ...............................................339
Longitudinal Chromatic Aberration .............................................................339
Lateral (Transverse) Chromatic Aberration ..................................................343
Practice Examinations ..........................................................................................345
Practice Examination 1 ..................................................................................345
Practice Examination 2 ..................................................................................349
Answers to Practice Examinations .......................................................................355
Practice Examination 1 ..................................................................................355
Practice Examination 2 ..................................................................................357
Index .......................................................................................................................361
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