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.%基于投影栅的3维面形测量中，包裹相位的提取过程中不可避免地会引入载频分量。为了准确地还原受物体3维形貌所调制的真实相位，必须要消除载频相位，采用剪切原理消除投影栅中的载频，首先通过对光场作剪切转化为相位梯度分布的新光场，再联合最小二乘解包裹算法进行相位展开，并与现有的方法进行了对比。结果表明，该方法能够有效地消除载频，减小重建误差，且其算法简单，可使重构相位值更接近待测的真实相位值。该方法在投影栅去载频的研究中是可行和有效的。
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