Calculation of the T matrix and the scattering matrix for ensembles of spheres

We present a method for determination of the random-orientation polarimetric scattering properties of an arbitrary, nonsymmetric cluster of spheres. The method is based on calculation of the cluster T matrix, from which the orientation-averaged scattering matrix and total cross sections can be analytically obtained. An efficient numerical method is developed for the T-matrix calculation, which is faster and requires less computer memory than the alternative approach based on matrix inversion. The method also allows calculation of the random-orientation scattering properties of a cluster in a fraction of the time required for numerical quadrature. Numerical results for the random-orientation scattering matrix are presented for sphere ensembles in the form of densely packed clusters and linear chains. (C) 1996 Optical Society of America.