Electromagnetic theory is used to calculate the gradual loss of polarization in light scattering from surface roughness. The receiver aperture is taken into account by means of a multiscale spatial averaging process. The polarization degrees are connected with the structural parameters of surfaces.

The two-scale model (TSM) is one of the most frequently employed approaches in scattering from multiscale surfaces such as ocean surfaces. It consists of combining geometrical optics (GO) with the small-perturbation model (SPM) to be able to cope with both the small-and large-scale components of the surface. However, well-known shortcomings of this method are the arbitrariness of the dividing scale and the sensitivity of the scattering cross section to the choice of this parameter. We propose to replace SPM with the first-order small-slope approximation (SSA1) to treat the small-scale roughness and derive the formulas for the corresponding TSM, referred to as GO-SSA. We show that GO-SSA is robust to the choice of the frequency cutoff and give a numerical illustration for the sea surface.Index Terms-Ocean scattering, small slope approximation (SSA), two-scale model (TSM).

The polarization of a coherent depolarized incident light beam passing through a scattering medium is investigated at the speckle scale. The polarization of the scattered far field at each direction and the probability density function of the degree of polarization are calculated and show an excellent agreement with experimental data. It is demonstrated that complex media may confer high degree of local polarization (0.75 DOP average) to the incident unpolarized light.

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The sparse-matrix-flat-surface iterative approach has been implemented for perfectly conducting surfaces and modified to enhance convergence stability and speed for very rough surfaces. Monte Carlo simulations of backscattering enhancement using a beam decomposition technique are compared with millimeter-wave laboratory experimental data. Strong but finite conductivity for metals or thin skin depth for dielectrics is simulated by an impedance approximation. This gives rise to a nonhypersingular integral equation derived from the magnetic field integral equation. The effect of finite conductivity for a metal at visible wavelengths is shown.

We show how disordered media allow to increase the local degree of polarization (DOP) of an arbitrary (partial) polarized incident beam. The role of cross-scattering coefficients is emphasized, together with the probability density functions (PDF) of the scattering DOP. The average DOP of scattering is calculated versus the incident illumination DOP.

Abstract-We present a boundary integral method for the numerical solution of the rigorous problem of wave scattering from rough surfaces under grazing illumination. The model of a locally perturbated plane is adopted: a finite patch of rough surface has its roughness flattened at the edges. The boundary formulation unknowns are the tangential components of the scattered field, defined as the contribution from the rough area. This way, the numerical domain of study is correctly bounded, even with a plane wave as incident field, and the sampled area is made independent of the incidence. This rigorous approach, called the grazing method of moments, is implemented on two-dimensional perfectly conducting surfaces and validated by comparison with a reference numerical solution for surfaces with Gaussian correlation functions. Now, the validity of approximate models at low-grazing-angles can be investigated; the small perturbation method and the small slope approximation are addressed in this paper. Scattering diagrams show how the performances of these methods deteriorate drastically at backward scattering angles as the incidence goes to grazing.