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`THOMAS SWAN 2007
`Finisar v. Thomas Swan
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`THOMAS SWAN 2007
`Finisar v. Thomas Swan
`IPR2014-00461
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`LIQUID CRYSTALS
`Applications
`and Uses _.
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`V01. 3
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`Edited by
`BIrendra Bahadur
`Display Systems Engineering
`Ufion Syflems Canada Ud.
`Eiabicoke, Ontario M9W 5A7
`Canada
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`Sinaogp Neerstethmmd HongKong
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`\‘:°World Scientific
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`Published by
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`World Scientific Publishing Co. Pte. Ltd.
`P O Box 128, Farrer Road, Singapore 912805
`USA ofiice: Suite 13, 1060 Main Street, River Edge, NJ 07661
`UK office: 57 Shelton Street, Covent Garden, London WC2H 9HE
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`Cover Design: By Amlr Novin, Kam Wan and Joy Tunnoch.
`' Microscope photograph ofa polymer dispersed liquid crystal display in
`quiescent mode between crossedpolarizers.
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`First published 1992
`First reprint 1994
`Second reprint (pbk) 1996
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`LIQUID CRYSTALS — APPLICATIONS AND USES (Vol.3)
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`Copyright © 1992 by World Scientific Publishing Co. Pte. Ltd.
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`All rights reserved. This book, or parts thereof, may not be reproduced in anyform
`orbyany means, electronicormechanical, includingphotocopying, recording orany
`information storage and retrieval system now known or to be invented, without
`written permission from the Publisher.
`
`For photocopying of material in this volume, please pay a copying fee through
`the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923,
`USA.
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`ISBN 981-02-2952-6 (pbk)
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`Printed in Singapore.
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`17. Applications of Liquid Crystals in Optical Computing 211
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`It is evident that these three characteristics will also be important in the use of LC's for
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`optical computing. One may say, in fact, that they already are being used to advantage. As
`Will be discussed below, active matrix twisted nematic LC television (LCTV) displays are
`pulled from their cases and peeled apart for use as electrooptic light valve arrays in optical
`connection prototypes5, and LC' 5 are already being used in an amazing variety of ways as
`electro--optic light valves to implement optical computing ideas7 Thus we predict that LC
`devices will have a major impact on optical computing and that commercial optical computing
`applications, optical inspecn'on, for example, will employ LC spatial light modulators In this
`review we highlight the first stirrings of what someday will be a rich and useful technology.
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`This chapter will focus on the conceived, prototyped, and potential uses of liquid
`crystals in Parallel Optical Processing (POP) and related technologies, and on the relevant
`operational characteristics of the LC devices used The minimum will be said about the internal
`liquid crystal details of the electro--optic devices themselves as these topics are adequately
`coveredin the other chapters of these Volumes and the citations therein. Rather, we focus on
`the role and operation of spatial light modulators, the basic parallel optical processing devices,
`and their implementation with liquid crystals. We provide a variety of examples of parallel
`optical processing devices and systems built around liquid crystal electro-optics.
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`17.2 LIQUID CRYSTAL SPATIAL LIGHT MODULATORS
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`In this section we review the LC devices useful'in parallel optical processing applica-
`tions and present some of the optical computing demonstrations and prototypes employing
`them, emphasizing the principal types: LC electrically addressed spatial light modulators
`including LC television-based devices, LC optically addressed spatial light modulators, and
`devices employing ferroelectric liquid crystals.
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`17.2.1 Spatial Light Modulators (ma
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`An important theme in optical computing is the exploitation of the intrinsic parallelism
`of optics to do processing and it is in this area that liquid crystals are especially useful. A
`particularly elegant and ancient realization of this idea is optical Fourier transformation,
`wherein the optical electric field distribution in the Fraunhofer diffraction plane is the Fourier
`transform of an image field8 The ready availability of coherent light sources has made Fourier
`optics a powerful1mage filtering and processing technique9 The basic advantage of optics in
`this application derives from its intrinsic parallelism, the ability of light rays of differing wave
`vector to occupy the same space and to pass through each other, and from the analog nature of
`light. To take advantage of this parallelism in a processing application, the positional
`dependencein one or two dimensions of the electric field of an optical wave front muSt be
`manipulatedin a way that can be easily and quickly changed, leading to the requirement for
`Spatial Light Modulators (SLMs) dynamically changeable devices which modify the
`amplitude phase and/or polarization of an optical wave front as a function of time and position
`across it Although, as the example of Fourier optics shows,ssome fundamental ideas of
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