Multiple Rayleigh Scattering of Electromagnetic Waves

Abstract
Multiple scattering of polarized electromagnetic waves in diffusive media is investigated by means of radiative transfer theory. This approach amounts to summing the ladder diagrams for the diffuse reflected or transmitted intensity, or the cyclical ones for the cone of enhanced backscattering. The method becomes exact in several situations of interest, such as a thick-slab experiment (slab thickness mean free path wavelength ). The present study is restricted to Rayleigh scattering. It incorporates in a natural way the dependence on the incident and detected polarizations, and takes full account of the internal reflections at the boundaries of the sample, due to the possible mismatch between the mean optical index n of the medium and that n₁ of the surroundings. This work does not rely on the diffusion approximation. It therefore correctly describes radiation in the skin layers, where a crossover takes place between free and diffusive propagation, and vice-versa. Quantities of interest, such as the polarization-dependent, angle-resolved mean diffuse intensity in reflection and in transmission, and the shape of the cone of enhanced backscattering, are predicted in terms of solutions to Schwarzschild-Milne equations. The latter are obtained analytically, both in the absence of internal reflections ( n=n₁), and in the regime of a large index mismatch ( ).