(1990) Fischer, Edgar; Sodnik, Zoran; Ittner, Thomas; Tiziani, Hans J.
For interferometric topography measurements of optically rough surfaces dual wavelength heterodyne Interferometry (DWHI) is a powerful tool. A DWHI system based on a two-wavelength HeNe laser and a matched grating technique is described. This set-up improves system stability and simple heterodyne frequency generation.
