THEORETICAL-STUDIES OF THE ENHANCED BACKSCATTERING OF LIGHT FROM ONE-DIMENSIONAL RANDOMLY ROUGH METAL-SURFACES BY THE USE OF A NONLOCAL IMPEDANCE BOUNDARY-CONDITION

Nonlocal impedance boundary conditions for p- and s-polarized electrom agnetic fields at the curved interface between vacuum and a metal, def ined by the equation x3 = zeta(x1), when the plane of incidence is the x1x3-plane, are derived. The conditions for the validity of a local i mpedance boundary condition are established. The results are used in c omputer simulation studies of the scattering of infrared and visible l ight from a large rms height, large rms slope, one-dimensional, random ly rough, metal surface. It is shown, by comparison with the results o f formally exact simulations, that the use of a local impedance bounda ry condition, even for light in the visible region of the optical spec trum, yields accurate results with a significant saving of computation al time.