Surface-topography of polished and oxide-coated BK-7 glasses investigated by atomic force microscopy

BK-7 glass surfaces, with high polishing qualities, and TiO2 and Ta2O5 films deposited on these substrates by reactive evaporation and reactive ion plating, are investigated by atomic force microscopy. The surface topography imaged by this method is compared to results of transmission electron microscopy, stylus technique and interferometric investigations. Differences in the roughness of the glass surfaces can be analyzed. The topography of Ta2O5 layers is strongly determined by the glass surfaces, while the surfaces of TiO2 films are not influenced by the substrate, which suggests differences in the growth behaviour of both oxides.