Shadow moire topography by means of the phase-shift method

We propose using the phase-shift technique to improve such shortcomings inherent to conventional shadow moire topography as low sensitivity and difficulties in computational processing. Because in shadow moire the reference grating and the deformed grating are mutually dependent, it is not possible to produce phase shifts of the fringe by moving the grating. However, fringe shifting that is actually constant regardless of fringe orders is achieved by changing both the gap between a specimen and the grating and the angle of illumination. This proposal is justified by a simulation test and some experimental results are shown for the verification of this trial.