Carrier removal method based on the principle of shearing

In the method of holographic interferometry and three dimensional profilometry of optic projection grating, the reconstruction of real phase is always affected by the carrier frequency, so removing carrier is a necessary step to obtain the accurate real phase. A novel method is proposed by introducing the shearing principle to calculate the carrier phase. Firstly, the distribution of phase gradient is obtained by shearing the optical field. Then, the mean value is subtracted from the obtained phase gradient to achieve carrier removal. That is, the proposed method is finished before phase unwrapping. The simulation calculation and experiment results show that this method is benefit to reduce the difficulty of phase unwrapping, to remove the carrier frequency effectively, and to make the reconstructed phase more closer to the measured true value.