Consummate solution to the problem of classical electromagnetic scattering by an ensemble of spheres II: Clusters of arbitrary configuration

The order-of-scattering approach developed earlier [Opt. Lett. 13,90 (1988)] and applied there to the case of linear chains of spheres is extended to the more difficult problem of scattering by clusters of spheres, the centers of which no longer need lie on a common axis. To help establish the validity of this most general calculation, comparisons are made between theoretical and experimental results for triangular and tetrahedral arrays of spheres. We also perform calculations based on an older method that requires the inversion of matrices, and we find that for the cases considered here the order-of-scattering method is substantially faster.