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`lérafik [.CPearofii, .SJ.
`Leno S. Pedrottl
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`7 3:; ..
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`IMMERVISION Ex. 2012
`LG v. ImmerVision
`|PR2020-00179
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`

`
`
`
`
`Second Edition
`
`to Optics
`
`
`
`FRANK L. PEDROTTI, S.J.
`Marquette University
`Milwaukee, Wisconsin
`
`Vatican Radio,
`Rome
`
`LENO S. PEDROTTI
`
`Center for Occupational
`Research and Development
`Waco, Texas
`
`Emeritus Professor of Physics
`Air Force Institute of Technology
`Dayton, Ohio
`
`In troduction
`
`Prentice Hall, Upper Saddle River, New Jersey 07458
`
`

`

`
`
`Library of Congress Catalaging-in-Publication Data
`Pedrotti, Frank L., (date)
`2 anyuction to optics/Frank L. Pedrotti, Leno S. Pedrotti.—
`n
`.
`.
`cm.
`Incpludes bibliographical references and index.
`ISBN 0-13-501545—6
`l. Optics.
`1. Pedroni, Lem 5.. (date) H. Title.
`QC355.2.P43
`1993
`92-33626
`535—dc20
`CIP
`
`Acquisitions Editor: Ray Henderson
`Editorial/ Production Supervision
`and Interior Design: Kathleen M. Lafferzy
`Cover Designer: Joe DiDomenico
`Prepress Buyer: Paula Massenaro
`Manufacturing Buyer: Lori Bulwin
`Proofreader: Bruce D. Colegrove
`
`© 1993, 1987 by Prentice—Hall, Inc.
`Upper Saddle River, New Jersey 07458
`
`All rights reserved. No part of this book
`may be reproduced, in any form or by any means,
`without permission in writing from the publishers
`
`W
`ISBN D-lB-SDLSHS-E
`
`9
`
`“W“
`80135‘
`
`1III III
`
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`

`

`of the beam is also the radiance of the source, at the initial point of the beam, or
`1 = L2 = Lo.
`Suppose, referring to Figure 2-6, that we wish to know the quantity of radiant
`power reaching an element of area (1143 on surface 52 due to the source element (M;
`on surface S1
`. The line joining the elemental areas, of length r12, makes angles of 01
`
`
`
`Figure 2-6 General case of the illumination of
`one surface by another radiating surface. Each
`elemental radiating area dAl contributes to each
`elemental irradiated area dAz.
`
`and 03 with the respective normals to the surfaces, as shown. The radiant power is
`d2(1)”, a second-order differential because both the source and receptor are elemen—
`tal areas. By Eq. (2-7) or Eq. (2-8),
`
`d2©12 =
`
`
`LdAldAz cos 0] cos 0;
`2
`1'12
`
`and the total radiant power at the entire second surface due to the entire first surface
`is, by integration,
`
` 2
`
`r12
`
`(23)
`q)” = I] L cos (9I cos (92 dA, dAz
`By adding powers rather than amplitudes in this integration, we have tacitly assumed
`that the radiation source emits incoherent radiation. We shall say more about coher-
`ent and incoherent radiation later.
`
`Al A2
`
`2-3 PHOTOMETRY
`
`Radiometry applies to the measurement of all radiant energy. Photometry, on the
`other hand, applies only to the visible portion of the optical spectrum. Whereas ra-
`diometry involves purely physical measurement, photometry takes into account the
`response of the human eye to radiant energy at various wavelengths and so involves
`psycho-physical measurements. The distinction rests on the fact that the human eye,
`as a detector, does not have a “flat” spectral rsponse; that is, it does not respond
`with equal sensitivity at all wavelengths. If three sources of light of equal radiant
`power but radiating blue, yellow, and red light, respectively, are observed visually,
`the yellow source will appear to be far brighter than the others. When we use photo-
`metric quantities, then, we are measuring the properties of visible radiation as they
`appear to the normal eye, rather than as they appear to an “unbiased” detector.
`Since not all human eyes are identical, a standard response has been determined by
`the International Commission on Illumination (CIE) and is reproduced in Figure
`2-7. The relative response or sensation of brightness for the eye is plotted versus
`wavelength, showing that peak sensitivity occurs at the “yellow-green” wavelength
`of 555 nm. Actually the curve shown is the luminous efficiency of the eye for pho-
`topic vision, that is, when adapted for day vision. For lower levels of illumination,
`when adapted for night or scotopic vision, the curve shifts toward the green, peaking
`at 510 nm. It is interesting to note that human color sensation is a function of illumi-
`
`Sec. 2-3
`
`Photometry
`
`13
`
`
`
`

`

`
`
`
`E 500
`x
`3
`g
`g 400
`E
`.1
`5 300
`
`———————————————————
`
`___________
`
`
`——— 342|m
`——————
`
`
`_________
`— 274|m
`
`
`0.7
`
`0-5
`
`a
`g
`32
`““5,
`g
`E
`0.5 3
`0A
`
`Vlkk
`
`0.3
`
`0.2
`
`OJ
`
` 200 ———————————————
`
`———~—
`
`‘0
`
`100
`
`———————
`
`400
`
`450
`
`500
`
`550
`
`600
`
`650
`
`700
`
`750
`
`Figure 2-7 CIE luminous efficiency curve. The luminous flux corresponding to
`l W of radiant power at any wavelength is given by the product of 685 1m and the
`luminous efficiency at the same wavelength: (I).()l) = 685V(,\) for each watt of ra-
`diant power.
`
`lower levels of illumination. One way to
`nation and is almost totally absent at
`confirm this is to compare the color of stars, as they appear visually, to their photo—
`graphic images made on color film using a suitable time exposure. Another, very
`dramatic way to demonstrate human color dependence on illumination is to project a
`35-mm color slide of a scene onto a screen with a low current in the projector bulb.
`At sufficiently low currents, the scene appears black and white. As the current is in-
`creased, the full colors in the scene gradually emerge. On the other hand, very in-
`tense radiation may be visible beyond the limits of the CIE curve. The reflection of
`an intense laser beam of wavelength 694.3 nm from a ruby laser is easily seen. Even
`the infrared radiation around 900 nm from a gallium-arsenide semiconductor laser
`can be seen as a deep red.
`Radiometric quantities are now related to photometric quantities through the
`luminous efficiency curve of Figure 2-7 in the following way: Corresponding to a ra-
`diant flux of 1 W at the peak wavelength of 555 nm, where the luminous efficiency
`is maximum,
`the luminous flux is defined to be 6851m. Then, for example, at
`A = 610 nm, in the range where the luminous efficiency is 0.5 or 50%, 1 W of radi-
`ant flux would produce only 0.5 X 685 or 3421m of luminous flux. The curve
`shows that again at A = 510 nm, in the blue-green, the brightness has dropped to
`50%.
`
`Photometric units, in terms of their definitions, parallel radiometric units. This
`is amply demonstrated in the summary and comparison provided in Table 2-1. In
`general, analogous units are related by the following equation:
`
`
`
`photometric unit = K (A) X radiometric unit
`
`(2-10)
`
`Where K (A) is called the luminous efficacy. If V(/\) is the luminous efficiency, as
`given on the CIE curve, then
`
`14
`
`Production and Measurement of Light
`5/5
`
`
`Chap. 2
`
`5/5
`
`