’ FUNDAMENTALS
`
`' OF OPTICS
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`)ICGRAW-HILL
`BOOK COMPANY
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`
`
`
`FRANCIS A. JENKINS
`Late Professor of Physics
`Unircrsily of California, Berkeley
`
`HARVEY E. WHITE
`
`Professor of Physics, Emeritus
`Director of I/Ic Lawrence Hall
`of Science, Emcrims
`University of California, Berkeley
`
`Fundamentals
`of Optics
`
`FOURTH EDITION
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`This book was set in Times Roman.
`The editors were Robert A. Fry and Anne T. Vinnicombe;
`the cover was designed by Pencils Portfolio, Inc.;
`the production supervisor was Dennis J. Conroy.
`The new drawings were done by ANCO Technical Services.
`Kingsport Press, Inc., was printer and binder.
`
`Library of Congress Cataloging in Publication Data
`Jenkins, Francis Arthur, dates
`Fundamentals of optics.
`First ed. published in 1937 under title: Funda-
`mentals of physical optics.
`Includes index.
`1. Optics.
`1. White, Harvey Elliott, date
`joint author.
`ll. Title.
`QC355.2.J46
`1976
`ISBN 0-07-032330-5
`
`75-26989
`
`535
`
`Prefa.
`
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`
`FUNDAMENTALS
`OF OPTICS
`Copyright © 1957, 1976 by McGraw-Hill, Inc. All rights reserved.
`Copyright 1950 by McGraw-Hill, Inc. All rights reserved.
`Formerly published under the title of FUNDAMENTALS OF
`PHYSICAL OPTICS, copyright 1937 by McGraw-Hill, Inc.
`Copyright renewed 1965 by Francis A. Jenkins and Harvey E. White.
`Printed in the United States of America. No part ofthis publication may be reproduced,
`stored in a retrieval system, or transmitted, in any form or by any means,
`electronic, mechanical, photocopying, recording, or otherwise,
`without the prior written permission of the publisher.
`8 910 KPKP
`83:2
`
`‘
`
`Part One
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`46 FUNDAMENTALS OF OPTICS
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`FIGURE 3B
`The focal points Fand F’ and focal lengths fand f’ associated with a single
`spherical refracting surface of radius r separating two media of index n and n’.
`
`In optical diagrams it is common practice to show incident light rays traveling
`from left to right. A convex surface therefore is one in which the center of curvature
`C lies to the right of the vertex, while a concave surface is one in which C lies to the
`left of the vertex.
`
`If we apply the principle of the reversibility of light rays to the diagrams in
`Fig. 3B, we should turn each diagram end-for-end. Diagram (a), for example, would
`then become a concave surface with converging properties, while diagram (b) would
`become a convex surface with diverging properties. Note that we would then have the
`incident rays in the denser medium, i.e., the medium of greater refractive index.
`
`3.2
`
`IMAGE FORMATION
`
`A diagram illustrating image formation by a single refracting surface is given in Fig.
`3D.
`It has been drawn for the case in which the first medium is air with an index
`
`n = l and the second medium is glass with an index n’ = 1.60. The focal lengthsf
`and f’ therefore have the ratio 1:1.60 [see Eq. (3a)]. Experimentally it is observed
`that ifthe object is moved closer to the primary focal plane, the image will be formed
`farther to the right away from F’ and will be larger, i.e., magnified.
`If the object is
`moved to the left, farther away from F, the image will be found closer to F' and will
`be smaller in size.
`
`All rays coming from the object point Q are shown brought to a focus at Q.
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`Rays from any of:
`ponding image psi:
`
`The elimination cf.
`treated in detail in
`
`Ifthe rays 2::
`monochromatic [5
`5'
`
`angles wit/z [/25 :3:5.
`image (see Sec. 2
`to images formed .
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`3.3 VIRTUAL
`
`The image .11 Q ::
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`SPHERICAL SURFACES 47
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`plane of a single spherical surface.
`
`FIGURE 3C
`How parallel incident rays are brought
`to a focus at Q' in the secondary focal
`
`Rays from any other object point like M will also be brought to a focus at a corres-
`ponding image point like M’. This idea] condition never holds exactly for any actual
`case. Departures from it give rise to slight defects of the image known as aberrations.
`The elimination of aberrations is the major problem of geometrical optics and will be
`treated in detail in Chap. 9.
`If the rays considered are restricted to pat-axial rays, 21 good image is formed with
`monochromatic light. Paraxiol rays are defined as those rays which make very small
`angles with the axis and lie close to the axis throughout the distance from object to
`image (see Sec. 2.12). The formulas given in this chapter are to be taken as applying
`to images formed only by paraxial rays.
`
`3.3 VIRTUAL IMAGES
`
`The image M’Q’ in Fig. 3D is a real image in the sense that if a flat screen is located
`there, a sharply defined image of the object MQ will be formed on the screen. Not
`all images, however, can be formed on a screen, as is illustrated in Fig. 3E. Light
`rays from an object point Q are shown refracted by a concave spherical surface
`separating the two media of index n = 1.0 and n’ = 1.50, respectively. The focal
`lengths have the ratio 1 : 1.50.
`Since the refracted rays are diverging, they will not come to a focus at any point.
`To an observer‘s eye located at the right, however, such rays will appear to be coming
`from the common point Q’.
`In other words, Q’ is the image point corresponding to
`the object point Q. Similarly M’ is the image point corresponding to the object point
`M. Since the refracted rays do not come from Q’ but only appear to do so, no image
`can be formed on a screen placed at M’. For this reason such an image is said to be
`virtual.
`
`3.4 CONJUGATE POINTS AND PLANES
`
`The principle of the reversibility of light rays has the consequence that if Q'M’ in
`Fig. 3D were an object, an image would be formed at QM. Hence, if any object is
`placed at the position previously occupied by its image, it will be imaged at the
`position previously occupied by the object. The object and image are thus inter-
`changeable, or conjugate. Any pair of object and image points such as M and M’
`
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