MiclHAEl P. KEATINQ
`
`CEOMETRic, PlnysicAi,
`d VisuAl Opiics
`AN
`
`SECONCI EdiiiON
`
`EVERLIGHT ELECTRONICS CO., LTD. ET AL.
`Exhibit 1016
`
`

`

`GEOMETRIC,
`PHYSICAL, AND
`VISUAL OPTICS
`
`Second Edition
`Michael P. Keating, Ph.D.
`Professor, Michigan College of Optometry,
`Ferris State University,
`Big Rapids, Michigan
`
`1^ U T T E R W O R T H
`GF N E M A N
`
`BOSTON OXFORD AUCKLAND JOHANNESBURG MELBOURNE NEW DELHI
`
`EVERLIGHT ELECTRONICS CO., LTD. ET AL.
`Exhibit 1016
`
`

`

`Copyright © 2002 by Butterworth-Heinemann
`
`A member of the Reed Elsevier group
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`All rights reserved.
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`No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any
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`publisher.
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`Every effort has been made to ensure that the drug dosage schedules within this text are accurate and conform to
`standards accepted at time of publication. However, as treatment recommendations vary in the light of continuing
`research and clinical experience, the reader is advised to verify drug dosage schedules herein with information found
`on product information sheets. This is especially true in cases of new or infrequently used drugs.
`Recognizing the importance of preserving what has been written, Butterworth-Heinemann prints its books on acid-
`free paper whenever possible.
`
`Library of Congress Cataloging-in-Fublication Data
`
`Keating, Michael P.
`Geometric, physical, and visual optics
`1. Optics 2. Optometry
`I. Title
`617.7'5
`ISBN: 0-7506-7262-5
`
`British Library Cataloguing-in-Publication Data
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`Printed in the United States of America
`
`EVERLIGHT ELECTRONICS CO., LTD. ET AL.
`Exhibit 1016
`
`

`

`6
`
`Geometric, Physical, and Visual Optics
`
`wavelength 530 nm is referred'to as green light, mono­
`chromatic light of vacuum wavelength 650 nm is
`referred to as red light, and monochromatic light of
`vacuum wavelength 460 nm is referred to as blue light.
`
`1.8 ABSORPTION
`Different materials have different absorption strengths
`for visible light. In many cases, the absorption strength
`of a material is also a function of the incident wave­
`length. A material may absorb the long (or red) wave­
`lengths more than the short (or blue) wavelengths.
`Wavelength-dependent absorption is called selective
`absorption.
`The total amount of light absorbed in a medium
`depends on the absorption strength and on the dis­
`tance that the light travels in the medium. A strong
`absorber is usually opaque, but when made thin
`enough it can transmit a significant percentage of the
`incident light.
`Gold, like other metals, is a strong absorber and is
`opaque for a typical thickness. However, a thin film of
`gold, deposited by vacuum evaporation techniques,
`transmits a significant percentage of light. The trans­
`mission of the thin gold film is actually a selective
`transmission. Gold absorbs more strongly in the red
`part of the spectrum. Thus, the transmitted light is
`greenish-blue.
`At the other extreme are weak absorbers. Weak
`absorbers are usually transparent, but even a weak
`absorber can become opaque if the thickness is great
`enough. Water absorbs red light weakly. In typical
`quantities, such as in fishbowls, bathtubs, and swim­
`ming pools, water is transparent for all wavelengths
`including red. However, in oceans illuminated by sun­
`light, the red light fails to penetrate deeper than 30 m.
`Clear glass is evenly transparent for a normal thick­
`ness. Tinted glass, as in stained glass windows, has a
`reduced transmission for the absorbed wavelengths.
`
`1.9 REFLECTION
`Transmission of light through a medium is decreased
`by any absorption that may be present. In addition to
`absorption, the amount of transmitted light can be
`reduced by surface reflection. The word reflection
`comes from the Latin word reflectere, which means to
`bend hack. Reflection is a surface or boundary phenom­
`enon. In general, whenever light is incident on a sur­
`face or a boundary between two different mediums,
`some of the incident light is reflected or bent back. The
`percent of the light reflected, and the wavelength
`dependence of that percentage, depends on the mater-
`
`ials involved and the angle of incidence of the incident
`light.
`level, the reflection process
`On a molecular
`involves an interaction of the incident light with the
`electrons in the atoms and molecules of the surface
`layers. There is a connection between a material's
`absorption properties and its reflection properties.
`Strong absorbers, such as metals, are strong reflectors.
`Weak absorbers, such as water and clear glass, are
`weak reflectors.
`Reflection is classified as either specular or diffuse.
`The word specular means mirror-like. Specular reflec­
`tion occurs when the surface is smooth and is the
`reflection involved in the formation of images by mir­
`rors or other smooth surfaces such as a pond of water.
`Diffuse reflection occurs when the surface is rough.
`Let us consider specular reflection first. Under
`rectilinear propagation conditions, the direction that
`light is traveling can be represented by straight lines
`called rays. Figure 1.4a shows a ray incident on a
`smooth surface. The line perpendicular to the surface
`is called the normal to the surface. The angle of incidence
`of the ray is defined as the angle 0-, that the ray makes
`with the normal. The angle of reflection is defined
`as the angle 9S that the reflected ray makes with the
`normal. The law of reflection states that the angle of
`reflection 9S is equal to the angle of the incidence 0t,
`or mathematically.
`
`6»i = es
`
`(1.1)
`
`The law of reflection is easy to determine and was
`known by the ancient Greeks. The law of reflection is
`independent of the wavelength of the incident light.
`Figure 1.4b shows three parallel rays incident on
`the smooth surface. The law of reflection applies to
`each ray so the three reflected rays are still parallel.
`Figure 1.4c shows three rays diverging from a point
`source of light. Again, the law of reflection applies to
`each ray. A scaled drawing easily shows that the
`reflected rays appear to be diverging away from a
`point below the surface. This is the image point that
`an observer looking at the reflected light would see.
`Flat bathroom mirrors as well as smooth water sur­
`faces form reflected images in this manner.
`Now let us consider diffuse reflection. Figure 1.5
`shows four parallel rays incident on a rough surface.
`Here the law of reflection still applies for each ray;
`however, the incident angles of each ray are different
`and, consequently, the reflected light is diffused in all
`directions. In diffuse reflection, the information car­
`ried by the incident light beam is lost and no reflected
`image of the original source can be seen. Instead, the
`diffusing surface itself becomes a secondary source.
`
`EVERLIGHT ELECTRONICS CO., LTD. ET AL.
`Exhibit 1016
`
`