Fortran code for computations of the reflection matrix by a semi-infinite discrete random medium. Calculation examples

• Electromagnetic scattering by discrete random media. • Coherent backscattering. • Fortran code for calculation of the reflection matrix. A Fortran code for fast computation of the reflection matrix of light for a semi-infinite discrete random medium in the case of oblique incidence of light on the boundary of the medium is described. It is assumed that the medium is homogeneous, isotropic and mirror symmetric and the waves propagating between the scatterers of the medium are spherical. The reflection matrix is the sum of two components, one of which corresponds to the incoherent part and is described by the vector radiative transfer equation. The second component corresponds to the coherent part and is realized in the weak localization effect. The code is designed to numerically solve both the vector radiative transfer equation and the equation for weak localization. Medium scatterers can be of arbitrary shape and composition, but in the general case it is necessary to pre-calculate the expansion coefficients of the scattering matrix by an elementary volume in series of generalized spherical functions, as well as the single scattering albedo and the scattering cross section. Several examples of reflection matrix calculation are given.