Comparative analysis of the propagation of light radiation in 2D and 3D media: II. Transmission of light radiation through strongly absorbing media with large-scale scatterers

In this paper, we present a review and comparative analysis of the propagat ion of scalar light radiation in disordered two- and three-dimensional medi a. Our main attention is focused on the propagation of radiation in media w ith large-scale (as compared with the wavelength of light) scatterers, when single scattering of photons is sharply anisotropic. In our analysis, we e mploy the method of separation of the total light flux into partial fluxes (method of partial fluxes), so that the nth partial flux describes the phot ons that change the sign of their velocity projection on the interior norma l to the surface of a medium exactly n times. The anisotropic part of the l ight flux (the zeroth partial flux) in 2D and 3D media is calculated with t he use of the standard small-angle approximation, when one can neglect the mutual influence of scattering and absorption processes. For the intensity of radiation in a 3D medium, we derive a relationship that extends the Moli ere distribution to the case of oblique incidence. We also reveal relation between the intensities of radiation in 2D and 3D media calculated in the s tandard small-angle approximation. Within the framework of the Fokker-Planc k approximation (diffusion approximation in angular variables), we calculat e the anisotropic part of the flux corresponding to the small-angle approxi mation in strongly absorbing 2D media, when the mutual influence of scatter ing and absorption processes changes the position of the maximum of radiati on intensity as a function of depth (rotation of the brightness body). Tran smission of Light radiation through strongly absorbing 2D media for large d epths (the regime of large depths) is investigated. We calculate and analyz e the variance of the angular distribution of photons, the mean path of pho tons in a medium, and the mean cosine of the scattering angle of photons as a function of the incidence angle and optical characteristics of the mediu m.