Error sources in deferred heterodyne moire deflectometry - An analytical study

The effects of the aperture size and shape of the photodetector and of the structure of the grating lines on the performance of deferred electronic heterodyne moire deflectometry are studied. It is shown that scanning of a moire fringe pattern parallel to an unshifted fringe yields periodical variations in the heterodyne phase and amplitude, which cause severe errors in the measurements.