Three-dimensional profilometry by projection type moiré topography using LC digital modulators

A projection type moiré topography by liquid crystal (LC) modulators is proposed for measuring thee-dimensional surface profile. The moiré contour without any original gratings is captured by the CCD camera during the exposure time by moving the pair of LC gratings electrically. The interval of the moiré contour is easily variable by changing the period of original LC grating. The phase shifting technique is applied to this moiré pattern by changing the phase of the both LC gratings. Some experimental results are shown as a practical application.