The effect of the modulation of Bragg scattering in small-slope approximation

Abstract Small-slope approximation (SSA) belongs to a class of ‘unifying’ scattering theories which reproduce small perturbations and semiclassic (Kirchhoff) results within appropriate limits. However, the most stringent test for such theories involves a two-scale situation when a small-scale roughness is located on a tilted plane. A ‘unifying’ theory should properly account for the effects of modulation of the scattering cross section associated with a large-scale tilt. This paper shows that SSA does properly take into account these modulation effects.