Excerpt from "The Great Detector Test"
by Andre' Idzikowski
CAR AND DRIVER
February 2002
P. 71

"Lidar is an especially fearsome speed-enforcement tool. A lidar gun works by firing a series of laser light pulses (with a wavelength of 904 nanometers) at a targeted vehicle. The device times the return of the reflected pulses and uses that number to compute the vehicle's speed. The lidar gun sends a narrow beam at its target; even at a distance of 1000 feet, the most intense portion of it is only six feet wide--narrow enough to pick up a single car out of a crowd.

But this narrow beam is also the lidar gun's major weakness. Unlike radar, it must be precisely aimed from a stationary position, typically at a range of 500 to 1200 feet. Lidar cannot be used in mobile units. Unfortunatley, because there is almost no "signal scatter" for a laser detector to pick up, most detectors can't warn you when Smokey is using lidar until the beam is already focused on your car--and that's usually too late to avoid a speeding ticket.

With roughly 25,000 of these units in use and their numbers growing by 4000 to 5000 a year, lidar represents a very serious threat. Fortunatley, detectors are being improved, and on several occasions we've been able to pick up the scatter signal of a laser clocking from a car ahead of ours in time to haul down our speed."

BTW, while the Valentine One and Escort Passport 8500 tied in the test for best lidar sensitivity, the Valentine One won the overall test by a wide margin.