LIDAR stands for Light Detection and Ranging. It's similar to RADAR, but uses a LASER to achieve its results. LIDAR is used, among many other applications, by the police to get speeders. Police Officers normally use portable LIDAR guns that can tell precisely the speed of a given car at a given moment. Due to the very nature of LASERs, it's impossible to use a radar detector to get protection against LIDAR. By the time the LASER beam hits your car (and, with some luck, the detector) the Police Officer will already have a precise reading of your speed.