A lidar is similar to the more familiar radar, and can be thought of as a laser radar. In a radar , radio waves are transmitted into the atmosphere, which scatters some of the power back to the radar's receiver. A lidar also transmits and receives electromagnetic radiation, but at a higher frequency.
Lidars operate in the ultraviolet , visible and infrared region of the electromagnetic spectrum.
Different types of physical processes in the atmosphere are related to different types of light scattering. Choosing different types of scattering processes allows atmospheric composition, temperature and wind to be measured. A simplified block diagram of a lidar contains a transmitter, receiver and detector system. The lidar's transmitter is a laser, while its receiver is an optical telescope. The basic operation of a laser is described here.