STOKES MATRIX OF A ONE-DIMENSIONAL PERFECTLY CONDUCTING ROUGH-SURFACE

We study theoretically the Stokes matrix of a perfectly conducting, one-dimensional rough surface that is illuminated by a polarized light beam of finite width whose plane of incidence is perpendicular to the grooves of the surface. An exact expression for the scattered field derived from Green's second integral theorem is used to compute the angular distribution of the Stokes matrix that has eight nonzero elements, four of which are unique. Results are presented for the numerical calculation of each matrix element averaged over an ensemble of surface profiles that are realizations of a stationary, Gaussian stochastic process. All four unique matrix elements are significant, with the diagonal elements displaying enhanced backscattering and the off-diagonal elements having complicated angular dependences including structures in the retroreflection direction. With the use of a single source function evaluated through the iteration of the surface integral equation obtained from the extinction theorem for the p-polarized field, we derive an approximate expression for the Stokes matrix that indicates that multiple scattering plays an important role in the polarized scattering from a perfectly conducting rough surface that displays enhanced backscattering. The numerical calculation of each of the contributions to the Stokes matrix, taking into account single-, double-, and triple-scattering processes, enables us to assign the main features of the Stokes matrix to particular multiple-scattering processes. Experimental measurements of the matrix elements are presented for a one-dimensional Gaussian surface fabricated in gold-coated photoresist. The results are found to be reasonably consistent with the theory, although we suggest that differences in one matrix element may be due to the finite conductivity of the experimental surface.