Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!cs.utexas.edu!wuarchive!texbell!attctc!thrax
From: thrax@attctc.Dallas.TX.US (Dan Dezelle)
Newsgroups: sci.electronics
Subject: electronics
Keywords: electronics laser radio-electronics
Message-ID: <9953@attctc.Dallas.TX.US>
Date: 30 Oct 89 22:29:35 GMT
Organization: The Unix(R) Connection, Dallas, Texas
Lines: 24

Does anyone remember an old 86 or 87 or maybe earlier version of
Radio-Electronics when they posted schematics and articles on
"laser listening" devices?  The laser would hit a pane of glass
and deflect the vibrations from voices in the room.  Then another
device would convert this code to english and could hear the
conversation through a set of headphones or what.. I dont have
this article anymore, but I was wondering how successful development
of these types of listening devices have become over the past
few years?  I remember the laser had problems with certian enviroments
because things like clouds would weaken or distort the ray from the
laser and it would have to be virtually a clear day (with no sun
spots) and a straight strong signal between the target and the laser.

I've seen other devices that you simply hook to a speaker or a radio
and point at the target and you can recieve conversations etc.. 

I was interested on what types of these systems exist and what kind
of range and clarity they offer?

Thanks for the help in advance.. 

Dan Dezelle