The CLidar is a scientific instrument used for measuring particulates (aerosols) in the lower atmosphere.
CLidar stands for camera lidar, which in turn is a portmanteau of "light" and "radar".
In this technique a very wide-angle lens images light scattered from a laser beam onto a CCD (Charge-coupled device) camera.
In the second figure, an image from the CCD camera is shown which is analyzed by adding up the individual pixels at each altitude.
Disadvantages include poor altitude resolution in the upper atmosphere, difficulty designing optics that gathers substantial amounts of light, and a loss in noise rejection (signal-to-noise ratio).