On acoustic scattering of beams

Abstract

When solving scattering problems using T-matrix methods, it is assumed that the incident wavefield can be expanded about a chosen origin as an infinite series of regular spherical wavefunctions. We develop such expansions for a variety of so-called quasi-gaussian beams found in the literature. If the incident wavefield does not solve the governing Helmholtz equation, T-matrix methods are not available, in general. This is the situation if one wants to scatter a paraxial gaussian beam of some kind. We also discuss such beams and their approximations.