IMPROVED GAUSSIAN BEAM-SCATTERING ALGORITHM

The localized model of the beam-shape coefficients for Gaussian beam-s cattering theory by a spherical particle provides a great simplificati on in the numerical implementation of the theory. We derive an alterna tive form for the localized coefficients that is more convenient for c omputer computations and that provides physical insight into the detai ls of the scattering process. We construct a FORTRAN program for Gauss ian beam scattering with the localized model and compare its computer run time on a personal computer with that of a traditional Mie scatter ing program and with three other published methods for computing Gauss ian beam scattering. We show that the analytical form of the beam-shap e coefficients makes evident the fact that the excitation rate of morp holoy-dependent resonances is greatly enhanced for far off-axis incide nce of the Gaussian beam.