Light scattering by “soft” particles of arbitrary shape and size

Abstract

A new approximate method of the analysis of light scattering by the “soft” particles of an arbitrary shape and size is presented in the paper. The main features of the method are as follows. (1) The particle–light interaction is divided into two parts. The first one is the scattering in its restricted sense (i.e. secondary radiation of light by the very substance of the particle). The second is the diffraction (in a narrow sense) of the exciting wave at the screen having the shape of the particle projection on a plane normal to the wave propagation direction. (2) The scattering analysis is performed in a three-dimensional spectral space with the aid of a Fourier-image of the scattering particle. This enables one to extend the Reyleigh–Gans approximation to the case of the particles of an arbitrary shape and size. (3) Summation of the scattering and diffraction fields is performed keeping in mind that the scattered field power should be equal to the diffracted one. Calculations of the indicatrices and the integral scattering cross-sections for a sphere (standard particle), spheroid, parallelepiped and cylinder are given as an illustration of the method. It has been shown that the method could be simply and successfully applied to the case of a particle of any shape, the PC-based calculation time being 10– 40 min and the accuracy about 20%.