  The roughness of glass surfaces after different stages of etching is
investigated by reflection measurements with a spectrophotometer, light
scattering, and atomic-force microscopy (in small scale), and Talysurf (in
large scale). The results suggest, there are three regimes during etching,
according to their optical reflectivity and roughness. The first and second
regimes are studied by the Kirchhoff theory and the third one is studied by the
geometric theory. Also, we compare the roughness obtained by the optical
scattering to the AFM results.
