Xref: utzoo rec.autos:25809 sci.electronics:8805 misc.consumers:15138
Path: utzoo!utgpu!watmath!watserv1!watsci!batman
From: batman@watsci.uwaterloo.ca (Marcell Stoer)
Newsgroups: rec.autos,sci.electronics,misc.consumers
Subject: Re: the laser speed measuring device
Message-ID: <226@watserv1.waterloo.edu>
Date: 28 Nov 89 20:36:18 GMT
References: <89325.164006BHB3@PSUVM.BITNET> <1517@nosc.NOSC.MIL> <89331.143306BHB3@PSUVM.BITNET>
Sender: daemon@watserv1.waterloo.edu
Reply-To: batman@watsci.UUCP (Marcell Stoer)
Organization: University of Waterloo, Waterloo Ontario, Canada
Lines: 16



The laser beam will probably be modulated ( ie chopped). This will make
jamming difficult, since you don't know the chopping frequency.  This in
turn increases the sensitivity of the measurement (phase sensitive detection)
.   0.9 microns is near IR and can be seen by the human eye if the beam is
scattered by a medium (ie glass does it all the time).  You'd be
able to see the beam with an IR viewer  ( they cost about $2K pre-built) if
you're interested in watching those kind of things.  Currently, radar is not
a perfect  speed detection technique either,  and can be fooled by a moving cop car or when multiple cars are being scanned.  The question is, is there less
noise at 0.91 microns +/- a bit than at radar wavelengths.  And is that
sufficient to make this technique a superior one ?

Marcell Stoer
Centre for Molecular Beams And Laser Chemistry
.


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