`
`
`
`
`
`
`THOMAS SWAN 2005
`Finisar v. Thomas Swan
`|PR2014-00465
`
`1
`
`THOMAS SWAN 2005
`Finisar v. Thomas Swan
`IPR2014-00465
`
`

`

`
`
`LIQUID CRYSTALS
`Applications
`and Uses _.
`
`V01. 3
`
`Edited by
`BIrendra Bahadur
`Display Systems Engineering
`Ufion Syflems Canada Ud.
`Eiabicoke, Ontario M9W 5A7
`Canada
`
`
`
`
`
`Sinaogp Neerstethmmd HongKong
`
`\‘:°World Scientific
`
`2
`
`

`

`
`
`Published by
`
`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
`
`Cover Design: By Amlr Novin, Kam Wan and Joy Tunnoch.
`' Microscope photograph ofa polymer dispersed liquid crystal display in
`quiescent mode between crossedpolarizers.
`
`,,
`9 ~~~~~~~
`
`‘
`
`‘
`
`‘
`
`I
`
`First published 1992
`First reprint 1994
`Second reprint (pbk) 1996
`
`LIQUID CRYSTALS — APPLICATIONS AND USES (Vol.3)
`
`Copyright © 1992 by World Scientific Publishing Co. Pte. Ltd.
`
`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.
`'
`
`~
`;
`'
`
`
`ISBN 981-02-2952-6 (pbk)
`
`Printed in Singapore.
`
`
`
`
`
`
`
`3
`
`

`

`
`”W,
`
`
`
`
`
`17. Applications of Liquid Crystals in Optical Computing 211
`
`It is evident that these three characteristics will also be important in the use of LC's for
`
`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.
`
`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.
`
`17.2 LIQUID CRYSTAL SPATIAL LIGHT MODULATORS
`
`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.
`
`17.2.1 Spatial Light Modulators (ma
`
`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
`
`
`
`
`
`4
`
`