Near- and far-field scattering from arbitrary three-dimensional aggregates of coated spheres using parallel computing

Abstract

Many scientific fields--including astronomy, climatology, and biology, among others--require the calculation of the scattered optical fields from multiparticle distributions. In the present study, we combine the established results for the scattering from clusters of homogeneous spheres and from single core-shell particles into a computationally tractable solution that is valid for irregular configurations of nonidentical, coated particles. The presented multiparticle scattering (MPS) model is based on a generalized Lorenz-Mie theory framework and the vector translation theorems for the vector spherical harmonics. We provide the MPS model in both the near and far fields, and for plane-wave and Gaussian beam illumination. A message-passing-interface protocol is used for the computational implementation of the model in a parallel computer program. The computer model is validated by verifying the accuracy of the vector translation theorems utilized in our theoretical methods and by qualitative comparison to existing multiparticle scattering data. We conclude by presenting the scattering profiles from several examples of particle distributions. This MPS model is a practicable method of calculating the optical fields arising in the scattering from particle aggregates and is straightforwardly extensible to arbitrary illumination and to more complex internal-particle structures, such as stratified spheres. Vital applications of this model include the exact computation of forces exerted on irregular objects in optical traps and the simulation of light propagation through biological tissues.