Two-wavelength double heterodyne interferometry is applied for topographic measurements on optically rough target surfaces. A two-wavelength He–Ne laser and a matched grating technique are used to improve system stability and to simplify heterodyne frequency generation.
© 1991 Optical Society of America
Original Manuscript: April 23, 1990
Published: August 1, 1991
Zoran Sodnik, Edgar Fischer, Thomas Ittner, and Hans J. Tiziani, "Two-wavelength double heterodyne interferometry using a matched grating technique," Appl. Opt. 30, 3139-3144 (1991)