  It is shown that in polar geometry and normal incidence the 2x2 matrix
technique - as discussed in detail in a preceeding paper [Phys. Rev. B 65,
144448 (2002)] - accounts correctly for multiple reflections and optical
interferences, and reduces only in the case of a periodic sequence of identical
layers to the Fresnel formula of reflectivity, which in turn is the theoretical
basis of the two-media approach, widely used in the literature to compute
magneto-optical Kerr spectra. As a numerical example ab-initio calculations of
the optical constants for an fcc Pt semi-infinite bulk using the spin-polarized
relativistic screened Korringa-Kohn-Rostoker method show very good agreement
with experimental data.
