How Police LIDAR (laser) Works

How Police LIDAR (laser) Works

LIDAR, which stands for LIght Detection And Ranging, sometimes referred to as Laser Radar or just Laser for short, is a tool used by many Police Departments across the country & around the world to calculate the speed of specific vehicles driving on the road. LIDAR calculates speed by first taking a series of distance measurements of a specific target vehicle, then calculates speed based on change in distance over time.

This is all accomplished by the police officer selecting a vehicle he would like to check the speed of, then aiming the LIDAR gun at that specific vehicle by looking through the scope of the gun. The officer then pulls the trigger which activates the LIDAR gun and it begins emitting a series of invisible infrared light pulses which travel toward the target vehicle at the speed of light. As each of the infrared light pulses hit the target vehicle they are reflected back to the LIDAR gun.

Due to the fact that the speed of light is constant, the LIDAR gun is able to calculate the distance of the target vehicle based on the amount of time each light pulse required to travel from the gun to the target vehicle and back to the gun. In less than a second, a long series of distance measurements will be made by the LIDAR gun of the target vehicle as it traveled along the road. At this point, by calculating the total change in the measured distances of the target vehicle over time , a accurate speed is calculated.

These light pulses are highly focused and very narrow is circumference, which is exactly the reason why the officer is able to select a individual vehicle to check the speed of, even if that vehicle is traveling within a group of other vehicles. This capability is unique to LIDAR and is one that RADAR lacks, making LIDAR a useful tool for Police. This is also the reason why LIDAR is very difficult to detect by RADAR/Laser detectors.

For specific details and photos of LIDAR guns, click here.