Multiple scattering and shape-related effects are an active and important field of research in the area of diffraction and scattering of electromagnetic waves by rough surfaces. Most of the rigorous numerical techniques for dealing with this problem were limited to the treatment of single-valued surfaces. We have extended the formulation of Mendoza- Suarez and Mendez (1997) for dealing with multi-valued profile functions in order to study the scattering of reentrant surfaces or cavities in both, the near and far-field. We have evaluated the near-field in circular cavities with narrow entrances, as well as in the case of clusters of rods or cylinders. Resonant frequencies are clearly identified for these structures. We have also found that our model could be useful to predict wave-induced oscillations in harbors of arbitrary geometry. This comes form the fact that the mathematical formulation of the problem of light scattering by cavities (in the case of p polarization) is similar to the one employed in the case of harbors of arbitrary shape, when a water wave arrives at its entrance (Hwang and Tuck, 1970; Lee, 1971). The results obtained with our model are in close agreement with previously reported theories and experimental data.
An experimental investigation of the angular distribution of the light scattered by randomly rough, two-dimensional, isotropic dielectric surfaces is presented. The surfaces, whose profiles constitute good approximations to Gaussian random processes with Gaussian correlation functions are fabricated in photoresist and characterized by means of a mechanical profilometer. The substrates employed in the fabrication of the samples consist of thick parallel plates of filter glass that absorb the incident light and whose refractive index is close to that of photoresist. This allows us to approximate experimentally a situation in which the light is scattered by a randomly rough interface separating two semi-infinite dielectric media, illuminated from the air side. With the rougher surfaces, we have observed enhanced backscattering effects in both, the s and p cases of incident polarization. Small but important cross-polarized components of the scattered light have also been observed.