Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!ll-xn!husc6!bbn!aoa!carl
From: carl@aoa.UUCP (Carl Witthoft)
Newsgroups: sci.physics,sci.electronics
Subject: Re: reflective light modulator
Message-ID: <319@aoa.UUCP>
Date: Thu, 25-Jun-87 07:37:50 EDT
Article-I.D.: aoa.319
Posted: Thu Jun 25 07:37:50 1987
Date-Received: Sat, 27-Jun-87 09:39:46 EDT
References: <845@ssc-bee.ssc-vax.UUCP>
Reply-To: carl@aoa.UUCP (Carl Witthoft)
Organization: Adaptive Optics Assoc., Cambridge, Mass. USA
Lines: 31
Xref: mnetor sci.physics:1778 sci.electronics:859

In article <845@ssc-bee.ssc-vax.UUCP> thornton@ssc-vax.UUCP (Ken Thornton) writes:
>Is there a material whose reflectivity can be modulated electronically?
>
>Earl Kirchner
>(I'm borrowing use of this account)
This is klugey, but quick:
IF you happen to have a polarized beam or at least a well-collimated and
coherent beam, 
	1) put a retro behind a pockels cell. Whack the drive voltage to
adjust cell transmission, and retro will reflect light back thru system. 
This has problems w/ holding appropriate xmsn. Forget it.
	2) If an acousto-optic cell is useable, then you can control the
diffraction efficiency of the cell and place the retro optics in the diffracted
beam path. Thus, if cell is off, R=0 ; if on R --> 1 .

What might be interesting,too, if you have a grad student to beat on, is
investigating some piezo-electric material in an evanascent (sp) wave
setup. My weird idea is: in "off"state, piezo is "far" from second prism
element, and total internal reflection takes place. In "on" state, piezo 
expands and contacts the second element, so transmission takes place.
Hmmm.. has anybody ever done anything like this?


-- 

Alix's Dad ( Carl Witthoft @ Adaptive Optics Associates)
{ima,harvard}!bbn!aoa!carl
{wjh12,mit-vax}!biomed!aoa!carl
54 CambridgePark Drive, Cambridge,MA 02140 617-864-0201
" If you're not afraid you're going to die on your windsurfer,
the wind isn't high enough to have a good time."