Convergence of the DDA for ensembles of objects of irregular shape

Abstract

The discrete dipole approximation (DDA) is commonly used to compute light-scattering properties of irregularly shaped particles. The DDA maps the particle into an array of cubic cells with side d < λ. For a randomly oriented irregularly shaped particle, DDA has been shown accurate when kd|m| ≤ 1, where k is the wavenumber and m is the particle refractive index. We demonstrate that the DDA yields robust results even when kd|m| ≈ 1.2 when applied to ensembles of irregularly shaped dielectric particles and kd|m| ≈ 1.3 for conductive particles. This finding can greatly reduce the computational load required for performing such computations.