What is police LiDAR? and How Does it Work?

police lidar

What is police LiDAR?

Police LiDAR is a technological device that is used by law enforcement officers to calculate the speed of a vehicle. It is a device that uses the principles of reflection to calculate distances between the device and the vehicle and then using this information to calculate the speed of the vehicle. Law enforcement officers have been able to use this device to determine the exact speeds that motorists are traveling and helping reduce road incidents and accidents. Police LiDAR technology also works on the principle of laser technology.


How does police LiDAR work?

Like all LiDAR devices, a police LiDAR also uses light to calculate the ultimate speed and velocity of a vehicle. This speed is reported back to the police officer holding the LiDAR device at extremely high speeds. Light is known to travel at extremely fast speeds, over 186,000 miles per second. This means that even for a professional driver, there is very little chance for one to slam on the brakes and reduce speeds in time for the laser signals to detect your speeds. The police LiDAR emits infrared laser beams that travel at the speed of light and hit your car. The laser beam is then bounced back to the device at the same speed.

How does police LiDAR work

After the laser has bounced back to the device, the device will calculate the time it takes for the round trip taken by the laser. It will then divide this by 2 and then use this time to calculate the distance between the vehicle and the device. The device will take over 1000 samples of this time and distance and then make a comparison of the change in distance between the samples and then use this data to calculate the speed of the vehicle. The accuracy of the device is achieved by taking several hundred samples over a very short period of time, say, a nanosecond.

One advantage of the police LiDAR device is that it shoots a very tiny “cone” of light from the gun. This means that the laser is able to pinpoint a specific vehicle without offering any prior warning. And this is why police officers are able to get the information they need. This small diameter of light ray also allows the police officer to target only one specific vehicle and obtain the reading of that one vehicle at any given time.

Obtaining a reading from the road

An officer will choose a single target from among several vehicles and take aim with the speed gun. The aim has to be directed at a reflective spot on the vehicle such as the headlights or the license plates. The officer will then pull the trigger on the gun to release the laser. The laser hits the vehicle and returns a reading of the vehicles speed, a process that seems almost instantaneous in the eyes of the police officer.

How to obtain a reading from one vehicle

The laser beams from the gun are usually very narrow and very accurate. Assuming the beam is a flashlight, if you point a flashlight on the wall from a short distance away, the diameter of the light is very small. However, as you move further away from the wall, the diameter of the beam on the wall grows bigger and bigger. The beam from the gun works in a similar fashion. The laser beam is very narrow and has a very small diameter as it leaves the gun. This gives it room to widen as it travels over a distance. However, the widening should not be too big as to cover more than one car at any given time. This explains why the speed LiDAR cannot work over extremely high distances. At a distance of, say, 1000 feet to 3000 feet, the diameter of the beam on the vehicle will have widened to about 3 feet or 1 meter. This allows the officer to pinpoint at one car at any given time and obtain a single reading every time the gun is used. This also contributes to the accuracy of the device.

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