Abstract

A new model of laser light scattering was obtained from experimental profilometer data and ray casting technique. Modelling was based on variables common to an angle resolved scatterometer and geometric optics. With this model, it was possible to obtain the scattering patterns, masking and shadowing effects, multiple lobes and backscattering. As advantage of the model, it was unnecessary to make statistical assumptions about the slope distributions. Satisfactory results were obtained from very small R_a values (0 mm) to relatively large values (7.53 mm). With no modifications or additions to the model, for different surface profiles, off-specular and multiple lobes were obtained. A complete set of equations is given, detailing the construction of the model. In addition to reproducing the scattering patterns reported in the literature, it was found that, if measured profilometer data are used, for large roughness values and large incidence angles, the scattering pattern does not hold the Helmholtz principle.

Key words: Modelling, geometric optics, roughness, reciprocity principle.