Analytical and computational models for a laser radiation field scattered by rough surfaces

Abstract

A 2-D spectral formalism using a superposition in plane waves for scattered and transmitted laser fields, to find solutions for Helmholtz equations, is described. The formalism is used to obtain the angular spectral amplitudes (ASA) of the laser radiation field scattered by rough surfaces. The equations are solved by numerical computation. To simulate the scattering from a real rough surface, various determin- istic profiles, combinations of them, and a random rough surface with Gaussian statistics are used. The latter is generated in an original man- ner, by using a filter function to transform the uniformly distributed ran- dom numbers, generated by computer, into a set of random numbers with Gaussian statistics. The formalism is tested by applying it to laser radiation scattered by a flat surface and the results are as expected. Eight different surfaces with the same average height and the same root mean square (rms) roughness are considered and they are supposed to be illuminated at various incidence angles by laser radiation with a known wavelength. For each surface, the ASA versus scattering angle dependence, corresponding to five angles of incidence, is represented. © 1996 Society of Photo-Optical Instrumentation Engineers. Subject terms: surface roughness; laser scattering; angular spectral amplitude; deterministic surface profile; random rough surface profile.