Wavelength scanning profilometry for real-time surface shape measurement

Wavelength scanning profilometry suitable for real-time surface shape measurement is proposed. A phase slope of the interference signal generated by a wavelength scan is measured at an individual image pixel on-line. The parallel outputs of these on-line measurements show a map of surface height in real time. Experiments where a tunable dye laser was used were conducted to simulate the real-time measurements of step objects with specular and diffuse surfaces. The results have shown that a height map is available at any moment during the wavelength scan, and the measurement accuracy of height increases as the scanning proceeds. For a scanning width of 25 nm, the accuracy was as high as 1 mu m. Analyses of the measurement accuracy are given. (C) 1997 Optical Society of America.