Two-dimensional small-rotation-angle measurement using an imaging method

A two-dimensional small-rotation-angle measurement system based on fringe projection is proposed and demonstrated. Simple and effective signal processing is described and applied to the angular calculation. Several measurements indicate a measurement accuracy of approximate to 0.4 arcsec, which is comparable to that of a high-priced autocollimator. The two-dimensional two-pitch grating used in our prototype system provides a wide measurement range, which is expected to reach 1300 arcsec for both x- and y-direction rotations. (c) 2006 Society of Photo-Optical Instrumentation Engineers.