Electron microscope observation of laser damage on germanium

A replica technique and electron microscopy have been applied to the study of ruby laser damage on germanium surfaces. Studies were made of the damage produced at very low laser energies far from the conditions of crater formation. The laser was operated in free generation conditions. The observed structures depend on the surface state and the crystallographic orientation of the sample. The damage was examined for mechanically polished surfaces as well as for mechanically polished and etched surfaces. The observed structures can be explained simply as a thermal effect. A phenomenological description of the observed damage is given and an explanation of the origin of the principal structures is suggested.