Singularities in behaviour of ellipsometric angles via functions of incidence angle of light were revealed experimentally under investigating four types of the samples manufactured on two materials: on dielectric-quartz and on metal-aluminium. Surface roughness was simulated by creation of artificial relief using a two-dimension orthogonal grating (random phase mask). Quadratic “defects” in the line were subjected to stochastic law of distribution. The “defects” were produced by etching in depth up to 1 μm and their sizes were equal to 25x25 μm and 2.5x2.5 μm on each of materials. The impact of sizes of artificial “defects” and their density upon polarization of reflected light was investigated by the multiple-angles-of-incidence ellipsometric measurements at wavelength 0.63μm. For the first time, a random phase mask was used for simulation of rough surface.