ABSTRACT
Light detection and ranging (LIDAR) hygrometry is a modern kind of optical methods for control of water vapor in the atmosphere. LIDAR is an optical remote-sensing technology that measures properties of the scattered light to obtain information about atmospheric composition, clouds, and aerosols. This chapter provides a detailed description of this technology, including the principles of operation and approaches to LIDAR systems fabrication. In particular, the physical principles of LIDAR operation are based on the measurement of the properties of the radiation that is returned either from molecules and particles in the atmosphere or from the Earth’s surface when illuminated by a laser source with a purpose to find information about the remote object. In its basic form, a LIDAR transmitter produces a pulse of optical radiation, which is directed into the medium of interest by the system optics. As the transmitted optical energy propagates, it is affected by the characteristics of the region of atmosphere through which it passes. Gas molecules and particles or droplets cause some of the energy to be scattered. A small fraction of this scattered energy is backscattered, that is, directed back toward the LIDAR system. This energy can be detected at the LIDAR receiver and analyzed using different approaches. The differential absorption LIDAR (DIAL) analyzers and Raman LIDAR systems are the most popular systems used for atmosphere monitoring. Specific features of the solar-blind Raman LIDAR operation and LIDAR systems designed for aircraft and satellite applications are also considered.
