Application of lateral shearing principle to carrier removal in grating projection

In 3-D shape measurement based on projection grating, the carrier frequency component will be introduced inevitably in wrapped phase extraction process. In order to accurately reduce the true phase modulated by 3-D shape of objects, the carrier frequency must be eliminated. The shearing principle was used to eliminate the carrier frequency in the projection gating. Firstly, the new optical field of phase gradient distribution was formed by shearing optical field, and then the phase was unwrapped with the least square algorithm. After comparing the existing methods, it was found the method used in this paper is valid. Simulation and experiments proved that this method can effectively eliminate the carrier frequency, reduce the reconstruction error,not only the algorithm is simple, but also the reconstructed phase is more close to the true measured phase. This method is feasible and effective on study about removal of carrier frequency in grating projection.