A noncontact optical technique for the measurement of thin-film thickness and surface roughness with 25-Å and 2-µm vertical and horizontal resolutions, respectively, has been described. It is based on a commonpath three-beam shearing interferometer, in which the outer beams act as a reference while the middle beam scans the surface. The results of this technique are comparable with the ones obtained with a stylus instrument.
© 1983 Optical Society of America
Kais Almarzouk, "Three-beam interferometric profilometer," Appl. Opt. 22, 1893-1897 (1983)