How Laser Speed Guns Work

Laser speed guns, also known as LIDAR (for light detection and ranging), work on the same basic principle as the more traditional radar guns: the purpose is to measure the relative speed of an approaching vehicle.

The radar gun emits a radio pulse, collects the reflection, and uses the Doppler shift between the two signals to determine the speed of the vehicle. Laser speed guns rely on a laser beam instead to calculate the vehicle’s speed. Laser speed guns are widely acknowledged as superior in accuracy to the radar gun.

An experienced New Jersey traffic ticket attorney can explain how laser speed guns work. Laser beams travel much faster than radio waves. These LIDAR devices typically send out a stream of 100 pulses within three-tenths (0.30) of a second. By measuring the length of time for each pulse to be sent and returned and dividing that number by two, it can calculate the distance to the vehicle. By comparing the distance calculated by each subsequent pulse, the speed can be determined.

There are far many more readings available when a laser speed gun measures speed than when a radar gun is used. Because laser speed guns can take more samples in a short period of time, they produce more accurate conclusions as to the speed of the vehicle.

Another difference is in the laser gun’s superiority in targeting a specific vehicle. Radar guns emit a constant, broad beam; consequently, it may be difficult to distinguish which one among multiple vehicles the reading was derived from. Laser light beam “cones” are quite small and, even at a distance of 1000 feet, may only have a diameter of three feet.

Nonetheless, speeding tickets issued as a result of evidence gathered through the use of a laser speed gun may successfully be challenged by an experienced New Jersey traffic ticket attorney.

One issue is the nature of the “reflective surface” that the laser hits. Should that surface be uneven or non-compliant, the reading may be inaccurate. Further limitations on the use of laser speed guns are that they must be stationary to get an accurate reading; they do not give accurate readings through glass.

Finally, the speed measured can be subject to doubt if the device itself was not properly maintained or the officer who employed it was either improperly trained or operated the device incorrectly.

If you’ve been ticketed for a traffic violation in the state of New Jersey, get the help of an experienced New Jersey traffic ticket attorney who can help you fight the charges. For a free initial consultation, do not hesitate to Contact Dan Matrafajlo today.