Calibration of the high sensitivity shadow moiré system using random phase-shifting technique

•This paper proposed an analytical method to calibrate the sensitivity of shadow moiré system.•The proposed method can provide an exact close-form result for the sensitivity.•The proposed method can determine the sensitivity without the need for the additional calibration experiments prior to the work of measurement.

In high sensitivity shadow moiré, the small Talbot distance limits the dynamic range. In this case, if the phase shift is introduced by object translation in its own plane, the object may be out of the dynamic range. The result is rapid changes in the period of fringe pattern. So problems arise when Dirckx׳ way is used to calibrate the fringe distance (or the sensitivity). In the presented paper, we describe a solution to solve the problem. The proposed method based on the idea of random phase shifting technique, which can extract the measurement phase not requiring a previous knowledge of the exact phase shift, and the sensitivity can be calibrated during the process of phase demodulation. Besides, the proposed method can provide an exact close-form result for the sensitivity. Simulations and optical experiments are implemented to verify the effectiveness of this method. The proposed method is suitable for the calibration of the sensitivity in phase shift shadow moiré.