Communications Corporation of Jacksonville

The information presented here is intended to present the basic

principles for understanding of how a Laser device is used to

determine the speed of an object.

Lidar is the name given to Laser speed measurement devices. It simply means,

Light Detection And Ranging. Lidar uses the principle of Time & Distance

to determine Speed. The lidar instrument transmits pulse of light out to a target.

This transmitted light pulse is reflected back to the instrument where it is analysed.

The time for the light to travel out to the target and back to the lidar is used to

determine the range to the target. A second Second Pusle is sent out to the target

and the Time and Distance is then calculated and averaged with the first and the

Speed is thus determined.(simplified for understanding)

Example of distance measurement:

assume the speed of light is c = 3.0E8 m/s

Traveling at the speed of Light, in 1 microsecond you would travel 492 feet.

Average Speed = Distance traveled

Time Taken