🚀 go-pugleaf

Your assumption that the device was hand held might be wrong.  If the beam 
were properly collimated it could have come from a great distance where even a 
tripod mount would have considerable jitter.  

More than likely, what you had was someone listening on your conversation 
through an amateur reflectance or interference device.  This would use a laser 
(professional devices would use an infra-red laser) to produce a reflection 
from your window which would be detected and amplified, or compared to a 
reference beam, to produce an audio output.  These devices are easily built, 
and often mounted to a small telescope or binoculars for an optical system for 
detection.  Since the glass in your windows will vibrate from any noise in the 
room, these devices can be quite sensitive.

Laser gun sites are usually only useful on side-arms which have a useful range 
that would be far smaller than the range required to produce a 1" beam 
divergence.  Long distance firearms would require so many adjustments for 
using a laser site at various distances that it would be impractical to use 
one.  A professional would just as soon use a standard telescopic site - an 
amateur would simply miss.


In article <4urchf$m16@news.rhrz.uni-bonn.de> UZSD78@IBM.RHRZ.Uni-Bonn.DE 
(Thorsten Franz) writes:>From: UZSD78@IBM.RHRZ.Uni-Bonn.DE (Thorsten Franz)
>Subject: Question: Curious Laser Beam
>Date: Wed, 14 Aug 1996 02:03:58 GMT

>Hello,

>when I was sitting in my living room tonight, a spot of red light (at
>most one inch in diameter) appeared on the wall and wandered over it,
>coming to rest on the back of the head of my girlfriend. I wasn't able
>to determine the exact size because it was obviously steered by a
>shaking hand.

>I thought it might have to do with a construction site across the
>street and went downstairs to check, but found noone. From down there
>it was clear that the angle wasn't right anyway and that the beam must
>have come from one of the dark windows in a nearby administration
>building, probably 5th or 6th floor.

>A laser pointer, as used for presentations on blackboards, would have
>been too unprecise over the estimated distance of 100 meters. I don't
>know of lab lasers with in-built magnifying glasses, and when you play
>with measuring devices you don't aim them at people's head because you
>are probably professional enough to know about the danger of blinding.
>You would also use a stand.

>So I figure someone might have been playing with the aiming device of
>a rifle, especially considering how restless the spot was. I will go
>to the police tomorrow and report the scary incident. If anyone can
>give me information that might be useful, confirm my suspicion (so I
>have something at hand when talking to a lazy officer), or calm me
>down, I will certainly appreciate it. :-)

>Maybe a physicist can draw conclusions from the estimated distance and
>approximate diameter of the beam, or you know what else portable,
>aimable lasers without a stand/tripod are made for.

>Thank you very much,
>kind regards

>-- 
>uzsd78@uni-bonn.de


Allen R. Sampson

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