Xref: utzoo rec.autos:15751 sci.electronics:5320 misc.consumers:8914
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!tank!kean
From: kean@tank.uchicago.edu (Keane Arase)
Newsgroups: rec.autos,sci.electronics,misc.consumers
Subject: Re: Correct Terminology (was Re: Radar Detectors (Ka band) ...)
Summary: Okay, let's report on the real rumors.
Keywords: radar, laser, lidar?
Message-ID: <1978@tank.uchicago.edu>
Date: 23 Feb 89 17:23:27 GMT
References: <603@icus.islp.ny.us> <7944@netnews.upenn.edu> <1895@tank.uchicago.edu> <5632@homxc.ATT.COM> <4057@alvin.mcnc.org> <3930@ttidca.TTI.COM>
Reply-To: kean@tank.uchicago.edu (Keane Arase)
Followup-To: rec.autos
Organization: University of Chicago
Lines: 61

[I've directed all follow-ups to rec.autos]

In article <3930@ttidca.TTI.COM> hollombe@ttidcb.tti.com (The Polymath) writes:
>
>Any way you look at it, 17.5 ft of spread per mile isn't even in the ball
>park.
>

Okay, I'm the one who reported it would spread 3.5 feet in 1000ft.

From Autoweek, 12/12/88:

David Williams, president of the Littleton, Colo., company that also makes
other lasers for uses such as underwater surveys, said that the four
pound device, which is seven inches long, uses an invisible laser beam
and is aimed with a scope.  It is fired like a pistol and registers the
speed of it's target in 1/4 to 1/2 second.  The device, which has not 
been given a formal name, has a range of 1500ft, although that may
be expanded to 2000 to 2500 ft.

How could a car be targeted at that distance?  Williams said one option
on the laser gun would be a magnifying scope.

The unit is expected to cost about $3,500, roughly $500 more than the most
expensive police radar unit and more than twice as much as what most radar
units cost.

Currently, there are no lasers being used for speed enforcement, although
the idea has been around for two decades, said Jerome Dennis, the chief
of laser product division of the federal government's Center for 
Devices and Radiological Health.

Dennis said he is not aware of any other devices that shoot lasers at humans,
other than those used for medical purposes.  He said the games that
children play use infrared beams, not lasers.

Dennis said before the unit can be tested by police or sold, it must be
reviewed by the Center to make certain that it meets safety standards.
He said the review HAS NOT YET TAKEN PLACE.  (emphasis mine - ka)

One attraction of a laser gun would be that it cannot be detected by radar
detectors, said Capt. Ken Casperson, the commanding officer of the 
traffic services division for the Michigan Department of State Police.

The radar used by police sends out a radio beam that may cover two or
three lanes of highway at 1000 ft.  Some of the beam hits the vehicle
and bounces back to the radar gun, providing speed of the target.
However, the rest of the beam, sometimes known as "scatter," continues
down the road where it can be picked up by radar detectors.

But there is little scatter with the laser gun, said Williams.  He said
the laser beam is aimed at one vehicle and at 1000 ft. is ONLY 3.5
FEET WIDE, so most of it would be reflected back to the laser gun.

[End excerpt.]
--
Keane Arase                   | Thought for the Day:
kean@tank.uchicago.edu        | Drive safely, Drive Offensively.
syskean@uchimvs1.uchicago.edu |   -- An old Chicago rush hour motto :-)

              *  Please file the usual disclaimers here  *