Lidar and Laser Remote Sensing

Abstract

Abstract Lidar or laser remote sensing involves the use of a laser beam as an optical probe of the surrounding environment and as a spectroscopic sensor of gases and constituents from afar. This chapter covers the basic techniques used for remote sensing of distant targets and surrounding atmospheric gases, but with an emphasis on the aspects of lidar that uses unique vibrational and rotational optical spectroscopy either in absorption or in Raman scattering. The basic physics of laser remote sensing is covered including that associated with the development of tunable laser sources, line width and wavelength parameters, atmospheric transmission through different atmospheric conditions of fog and gas cloud concentrations, and the detection of the lidar backscattered radiation. Aspects of the lidar equation are presented to help predict the signal‐to‐noise ratio (S/N) of the remote sensing signal, the influence and trade‐offs of using different targets (hard targets or atmospheric aerosols) and the use of different spectroscopic interactions including Raman, fluorescence, and nonshifted backscattered lidar radiation. Examples of current research using differential‐absorption lidar (DIAL) and Raman spectroscopic measurements are presented with specific examples of the remote sensing of NH 3 clouds and CO 2 in the atmosphere. Finally, the important role that the development of new tunable lasers plays in lidar sensing is emphasized.