Multiple Scattering Effects in Aerosols: Theoretical Investigations
Contractor rept. Sep 1979-Jul 1981
INSTITUTE FOR ATMOSPHERIC OPTICS AND REMOTE SENSING HAMPTON VA
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This report presents the results of a theoretical investigation on the effects of multiple scattering MS on the propagation of laser beams through scattering media. The theoretical formulations are given for three methods - two exact and one approximate - based on the solution of the radiative transfer equation in the small angle approximation. Computer codes were developed, optimized, and checked for consistency. The two methods are exact in the sense that the only approximation made is the small angle approximation. Using one of the exact methods, numerical results were obtained for contributions to MS due to various orders of scattering in the forward direction for various optical depths. The total MS contributions obtained by the two exact methods are shown to be in excellent agreement. The laser beam broadening due to MS by aerosols is also shown. Using the approximate method, numerical results were also obtained for MS effects as functions of detector field of view, as well as the size of the detectors aperture namely, for the cases when it is the same size as or smaller or larger than the laser beam diameter. The contrast between the on-axis intensity and the received power is shown for the last three cases.
- Lasers and Masers