Heterodyne profiling instrument for the angstrom region.

An instrument for surface profile measurements without need of a separate reference surface is presented. Height variations of 50 A can be resolved, while the theoretical height resolution is 4 A. The lateral resolution is 3 μm, which also can be improved. Scan lengths of 100 μm to several millimeters are achieved, and no extensive alignment of the sample is needed. The instrument is a heterodyne interferometer, and the sample is used as a reference surface.