Scattering Of A Spheroidal Particle Llluminated By Gaussian Beam

In this thesis, the analysis of electromagnetic wave scattering by spheroids illuminated by Gaussian Beam has been done. The main contributions of the author抯 work are as follows: (1).We have studied the scattering of the Gaussian beam by a spheroidal particle and presented an approach to expand the Gaussian beam in terms of the spheroidal wavefunctions in spheroidal coordinates for oblique incidence . The determination of the beam-shape coefficients G~ (c), F~ (c) is effected by first expanding the wave in terms of the analogous spherical vector wave function (which are orthogonal over the surface of a sphere) and then using the expansion of the spherical wave function in terms of the spheroidal wave functions. Thus, the beam-shape coefficients of the Gaussian beam in spheroidal coordinates can be computed conveniently by using the known expression of g~ coefficients in spherical coordinates. As so far we know, no analysis has been presented for the beam-shape coefficients of the Gaussian beam by a spheroidal particle. (2).We discuss the numerical computation of spheroidal wave functions and give numerical values of the spheroidal eigenvalues. (3).Theoretical expression for the boundary condition for electromagnetic scattering by spheroidal particles is given by virtue of the method presented by Shoji Asano and Giichi Yamamoto. The incorrect coefficients of expansions given by Shoji抯 has been corrected .All above results have been verified by Mathmatica. (4).The unknown expansion coefficients of scattered and internal f electromagnetic fields are determined by a system of equations derived from the boundary conditions regarding the continuity of tangential components of the electric and magnetic vectors across the surface of the spheroid. The numerical values of the expansion coefficients and scattered intensities distribution for incidence of Gaussian beam in the on-axis case are given. (5).A theoretical analysis for the rainbow is given. The scattered intensities distribution for particle in the atmosphere are computed.