Scattering from long prisms using ray tracing combined with diffraction on facets

A new model suitable for rapid computation of scattering on faceted dielectric objects such as ice crystals is presented. It combines ray tracing with diffraction on flat facets. The model allows retaining the ray nature of the internal field by calculating the diffraction component using an approximation for the far field direction of the Poynting vector. While this approach is similar to methods using the uncertainty principle, it does not require the use of angular distributions of diffracted rays, which leads to negligible computational overheads with respect to pure ray tracing. Results showing angle-dependent scattering computed for long hexagonal prisms, including phase functions and degree of linear polarization, are presented and compared with other models and with measurements on hexagonal fibers