Anisotropic scattering of light in random media: incoherent backscattered spotlight.

We discuss the anisotropic scattering of unpolarized light in optically dense random media and the flux analysis of an incoherent backscattered spotlight. We present a classic statistical approach based on the photon-diffusion approximation and Monte Carlo simulations to describe the anisotropic propagation of ballistic and long-path photons in a semi-infinite random medium with internal reflections. An imagery technique with high gray-level resolution is used to measure the surface flux density in the incoherent backscattered spotlight. We investigated light scattering from homogeneous suspensions of nonspherical alumina particles in water. We analyzed the particle volume fraction and the particle-size dependence of the surface flux density to determine the transport mean free path and the optical properties of scatterers from scaling laws that account for short-path photons and internal reflections.