Abstract

The atmospheric aerosols which are used as targets are randomly distributed and have random motion. They are of different sizes and have separations much greater than the wavelength of the laser. It is also assumed that there are a sufficient number of them present in the scattering volume to form a diffuse, extended target. The radiation scattered by any aerosol has random phase and amplitude with a Doppler shifted frequency. The signals from the various scatterers which make up the target combine to form a speckle pattern at any point along the backscattered beam. The speckle size is approximately, λL/b, where, b, is the radius of the beam on the diffuse target. Therefore, as the beam size on the diffuse target increases, the speckle size at the receiver decreases. The field across a speckle pattern is produced by the addition of a number of signals of random phase, thus the speckle pattern will change as each particle moves, thereby generating spatial and temporal changes in intensity. Churnside and Yura considered the spatial and temporal properties of the aerosol induced speckle in Reference 1.

© 1987 Optical Society of America