What is the principle behind lidar speed detection?

Lidar (Light Detection and Ranging) works by emitting laser beams towards a moving vehicle and measuring the time it takes for the light to bounce back to the lidar unit. This time-of-flight measurement allows the system to calculate the distance to the vehicle. By taking multiple measurements over time, the lidar device can determine how far the vehicle has moved, and thus calculate its speed using the formula for speed (distance divided by time).

Using laser beams provides high precision in both distance and speed measurements, making lidar a reliable tool for speed detection. This principle is key to the technology and underlies its effectiveness in various conditions, such as in daylight or at long ranges. The other options focus on concepts that do not pertain to how lidar operates, such as sound frequency or engine noise, which do not factor into the functioning of this type of speed detection.