Study On Scattering Characteristics Of Gaussian Beam By Typical Particle

In this thesis, an analytic solution to the scattering of the Gaussian beam by a spheroidal particle and by an infinitely long circular cylindrical particle in the general case of arbitrary illumination is constructed. The main contributions of the author's works are as follows:1. Based on the generalized Lorenz-Mie theory and addition theorem for spherical vector wave functions under coordinate rotations, an expansion of the incident Gaussian beam in terms of the spheroidal vector wave functions natural to a spheroid of arbitrary location and orientation is derived, and also the representations for the beam shape coefficients. For the special cases of the spheroidal particle center located on the Gaussian beam axis and the incident plane wave, the simplified expressions are given.2. The relations between the cylindrical vector wave functions of the first kind and the spherical ones are provided, on the basis of which a description of the expansion of the Gaussian beam with arbitrary illumination in terms of the cylindrical vector wave functions is presented, and also the representations for the corresponding beam shape coefficients. For the special cases of the cylinder axis intersecting the Gaussian beam axis and plane wave illumination, the simplified computational expressions are available.3. The scattering of the Guassian beam with arbitrary illumination by a spheroidal particle is studied by means of the method of separation of variables, thus extending the parallel propagation of the Gaussian beam available in the literature to the general case of arbitrary illumination.4. For a concentric spheroid with non-confocal boundaries, the difficulty appears of handling the electromagnetic boundary conditions as its boundaries can be the coordinate surfaces in different spheroidal systems. In this thesis a theoretical procedure is developed to deal with the non-confocal boundary conditions, based on which the Gaussian beam scattering by an arbitrarily oriented spheroid having layers with non-confocal boundaries is studied.5. A method of calculating the scattered electromagnetic fields of an infinitely long circular cylinder of arbitrary orientation illuminated with a Gaussian beam is presented, and the general expression to compute the scattered fields in the far zone is obtained. -For the case of a tightly focused Gaussian beam, naturally a three-dimensional problem, the scattering characteristics that are different from those for an incident plane wave are described in detail...