A Laser speed measuring device, unlike Radar, works using a light beam, which travels in a very narrow beam, and in a straight line, rather than a radio wave. Due to the very narrow beam, the Laser speed measuring device can be used to pick a specific target vehicle out of a group of vehicles. The Laser beam is reflected off the target vehicle and back to the device. The device then calculates the speed of the vehicle and displays it in miles per hour to the operator. The citation will reflect the speed you were traveling along with the distance from the device at the time it was checked.