Basic principles of atmospheric lidars
Measuring atmospheric gas with LIDAR

Also known as laser radar, a lidar is a sensor that emits a directional beam in the optical domain towards a target, and analyzes the backscattered beam to measure certain physical parameters. The name LIDAR alludes directly to RADAR (Radio Detection and Ranging), whose principle is identical, with the difference that lidar operates in the optical domain and radar in the radiofrequency domain. Table 1 shows the limits of the lidar, radar and terahertz domains (values may vary slightly from one author to another).