Backscattering of plane waves in a composite system containing a rough surface and anisotropic scatterers

In this paper, we study the backward scattering of light in a composite system consisting of a rough surface and anisotropic scatterers. Based on the theories of Kirchhoff's rough surface scattering and particle backscattering, we develop a theoretical framework applicable to modeling backscattering from rough surfaces in turbid media. We then give theoretical and simulation results of this model in the quasi-ballistic regime under the single scattering approximation. For the turbid media conditions and surface roughness parameters considered in this study, it is found that the albedo distribution of the system in the small exit angle interval is mainly determined by rough surface scattering, and particle scattering makes a major contribution in the large exit angle interval. The different proportions of scattered light intensity between rough surfaces and particles in different intervals lead to the inflection points of the albedo distribution. Additionally, the anisotropy factor, scattering mean free path, and roughness of rough surfaces affect the albedo distribution. The theoretical results of the proposed model are in good agreement with the Monte Carlo simulation results.