Abstract
Grazing incidence reflectivities of gold surfaces have been measured with monochromatic soft X-rays at various wavelengths. The results strongly depend on the substratum material comprising zerodur, nibodur and kanigen onto each of which 250 Å of gold are evaporated. Accordingly, different sets of optical constants are derived by a straight foreward application of Fresnel's reflection formulae. To account for these differences the influence of scattering by surface microroughness is discussed.