Fumio KOBAYASHI^*, Yukitoshi OTANI, and Toru YOSHIZAWA¹

Center for Optical Research and Education, Utsunomiya University, Utsunomiya 321-8585, Japan ¹School of Biomedical Engineering, Saitama Medical University, Hidaka, Saitama 350-1241, Japan

(Received September 7, 2010; Accepted January 19, 2012)

A projection-type moiré topography that uses a frequency modulation technique with two liquid crystal digital gratings (LCDGs) is proposed. In this method, moiré contours are filtered to remove the image of the original grating from the moiré contours by moving the image created by the LCDGs. The frequency modulation technique can be used to analyze the fringe of step heights or other separate areas by modulating the fringe interval. The experimental results showed the possibility of measuring three-dimensional shapes and step heights.

Key words: projection-type moiré topography, frequency modulation technique, three-dimensional profilometry

^*E-mail address: f-koba@cc.utsunomiya-u.ac.jp