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From: henry@utzoo.UUCP (Henry Spencer)
Newsgroups: sci.physics,sci.electronics
Subject: Re: reflective light modulator
Message-ID: <8214@utzoo.UUCP>
Date: Sat, 27-Jun-87 22:36:18 EDT
Article-I.D.: utzoo.8214
Posted: Sat Jun 27 22:36:18 1987
Date-Received: Sat, 27-Jun-87 22:36:18 EDT
References: <845@ssc-bee.ssc-vax.UUCP> <12862@topaz.rutgers.edu>, <320@aoa.UUCP>
Organization: U of Toronto Zoology
Lines: 14

> >How about liquid crystals?...
> 
> Can this work? I'm worried ...
> ... I hear LCD's can't run DC, so need to pulse the beam
> on&off at some rep rate, which may not be acceptable.

The excitation signals to LCDs can't be DC (or an AC signal with much of a
DC component) for any length of time without damaging the LCD.  But as I
understand it, this does not imply that the LCD's optical properties pulse
in time with the signal.  LCDs don't care about polarity, and their response
time is quite slow, so the AC signal produces pretty much a DC result.
-- 
Mars must wait -- we have un-         Henry Spencer @ U of Toronto Zoology
finished business on the Moon.     {allegra,ihnp4,decvax,pyramid}!utzoo!henry