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From: yerazuws@rpics.UUCP
Newsgroups: sci.electronics,sci.physics
Subject: Re: Laser eavesdropping
Message-ID: <1049@rpics.RPI.EDU>
Date: Fri, 27-Mar-87 09:16:08 EST
Article-I.D.: rpics.1049
Posted: Fri Mar 27 09:16:08 1987
Date-Received: Sat, 28-Mar-87 13:08:32 EST
References: <499@sw1e.UUCP>
Lines: 14
Keywords: modulation
Xref: utgpu sci.electronics:427 sci.physics:973
Summary: Interferometry.

In article <499@sw1e.UUCP>, uusgta@sw1e.UUCP (uusgta) writes:
> I was thinking about the commonly mentioned electronic snooping technique
> of pasting a reflective dot to a window and listening to conversations in the
> room by bouncing a laser off this vibrating mirror. 
 
The technique works by interferometry.  As the dot moves, the distance
between the dot and the laser changes.  By creating an interference pattern,
it can be determined how far and in which direction it moved.
	
By the way, you really don't need the dot.  A dirty window is enough.

-- 
	-Bill Yerazunis "VAXstation Repo Man"
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