By Matt Busse
Sunday, June 25, 2006
Laser gun in hand, Virginia State Police Trooper John Turner stood in the grass in the middle of U.S. 460 outside Appomattox.
A tractor-trailer approached, heading west.
Turner aimed squarely between the headlights.
He pulled the trigger.
63 miles per hour. 1,800 feet away.
That was the readout on Turner’s Pro Laser III, one of seven handheld speed guns the state police’s Appomattox-based division recently received.
The guns, called “lidar” - for “light detection and ranging” - are touted as far more precise in aiming than traditional radar guns.
In general, a radar gun works by sending out a signal and measuring how a moving object changes the way that signal bounces back to the gun.
But the signal fans out in a cone shape from the gun, which police say can make it difficult to single out a car in a group.
“It covers too broad of an area,” said Sgt. David Cooper.
A lidar gun’s laser beam is much narrower than radar: at 1,000 feet away, the beam’s only about three feet wide, Cooper said.
The laser gun measures speed based on the time it takes for the laser beam to come back.
That extra precision comes in handy during heavy traffic times such as rush hour and holiday weekends, he said.
The laser guns aren’t entirely replacing radar. They’ll just be another tool for state police to use.
The State Police’s Division Three, based in Appomattox, covers 15 counties and three cities, including Lynchburg.
It received seven of the $3,400 laser guns in April.
Division Six, which covers two cities and 13 counties, including Bedford County, is testing one of the guns in Martinsville.
“It’s like anything else. You get a few and test them out,” said Sgt. Robert Carpentieri.
Lidar guns aren’t entirely new to the area.
The Lynchburg Police Department has had one for about two years, according to Lt. Michael Staley of the Lynchburg Police Department.
But with the state police’s recent shipment, the likelihood of speeders being nabbed by laser increases.
Lidar guns have a few drawbacks.
For one thing, if a trooper’s using it in a car, he has to roll the window down - the laser beam bounces off glass.
And, of course, the gun doesn’t do all the work.
For a traffic ticket to hold up in court, police still have to be able to say they saw the car they were aiming at, which they call “visual confirmation.”
“Anything we can do to eliminate the possibility of error, we do it,” Cooper said.
And despite the laser guns’ advantages for police, they’re already running up against technology-savvy speeders determined to thwart them.
Devices advertised as being able to block laser speed detection, called laser jammers, are already available on the Internet.
In Virginia, however, all radar detectors are illegal to own.
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