Surface roughness characterization of smooth optical films deposited by ion plating

The surface topography of Ta205 and Si02 layers deposited by ion plating was studied by atomic force microscopy (AFM) and total integrated light scattering. A nearly perfect replication of the microroughness of superpolished and conventionally polished substrates was observed by AFM. Consequently, the scattering was not increased by the intrinsic microroughness of the films. However, local scatter maxima occured that were attributed to local defects.