Laser speed guns transmit short
bursts of invisible light which bounce off a target vehicle and
return to the laser gun. By timing the outgoing and return trips
of the light bursts, it can compute the target's speed. The laser's
biggest selling point is its narrow beam--only about three feet
wide at a 1,000 feet--a feature that provides nearly foolproof target
identification. (In comparison, a radar's beam is about 250 feet
wide at 1,000 feet.) Laser guns must be used from a stationary position
and are most effective at short range, usually targeting traffic
at 700 feet or less.
Since laser guns use a specific light frequency, it is possible
to detect a laser's signature light pulses. Keep in mind that laser
detection is very different than microwave radar detection.
Since the narrow laser beam generates very little scatter--random
bits of electromagnetic energy bouncing down the road--it is much
tougher to detect than a radar gun that blankets the countryside
with its powerful, easily detectable microwave beam.
Laser guns operate exclusively in instant-on mode, not transmitting
until the trigger is squeezed. For this reason a detector usually
will offer little advance warning. Similar to instant-on radar,
if you're the target there will be little time to slow down. Your
best hope is to use a laser detector with high sensitivity and a
good field of view--the crucial ability to sniff out off-angle laser
beams. So equipped, there's a small chance for advance warning of
a laser working traffic up ahead.
While in theory laser detectors can
spot a laser beam coming from behind, we've found that a direct
hit must be scored on the radar/laser detector for an alert to sound. At that point you can forget about spiking the brakes; you're toast. Fortunately,
nearly all laser ambushes will be coming from the front. Laser jamming
is easily done and legal in most states as well. The best laser jammers we've tested are more than a match for the latest laser guns.
For more information about laser speed enforcement technology and countermeasures, check out
Lasers: How They Work and How to Avoid Them.
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