Lidar measurement of particles and gases by elastic backscattering and differential absorption

The principles of light detection and ranging with lasers are considered, taking into account the optical radar equation, optical radar systems and equipment, and aspects of eye safety. An investigation is conducted regarding the atmospheric interactions which determine the received optical radar signal. Attention is given to backscattering from gas molecules, resonance scattering, backscattering from particles, particle shape effects, backscatter-to-extinction ratio, attenuation due to gas molecules and particles, and multiple scattering. A description is provided of the differential absorption optical radar technique. An interpretation of single-wavelength optical radar measurements in terms of atmospheric significance is also given and examples of optical radar measurements are presented.