提出一种基于“2+1”相移算法的正交复合光栅投影三维测量方法。用2帧相移量相差为π/2的正弦光栅加1帧背景光代替传统正交复合光栅相位测量轮廓术(OCGPMP)中3帧等相移正弦光栅，并将受背景项调制的载波频谱放在受2帧正弦相移光栅调制的载波频谱中间，由于背景项只有直流分量对载波的调制，与相邻调制载波交流调制成分不会发生频谱混叠，从而拓展了两相移光栅的载波频谱宽度，有效减少了频谱混叠，降低了相位测量误差。计算机仿真和实验结果表明，该方法将测量精度提高到传统OCGPMP的1.74倍。

A novel method is proposed from the perspective of restructuring the image patterns to be modulated to restrain the spectrum overlap. Three sinusoidal gratings with equal phase shift in traditional orthogonal composite grating based phase measurement profilometry (OCGPMP) are replaced by two sinusoidal gratings having π/2 phase shift and a uniform flat image. Moreover, set the spectrum modulated by the flat image between the spectra modulated by two of the sinusoidal gratings. For the flat image, carrier is only modulated by the direct current component. Therefore the spectrum overlap between the adjacent carrier channels is smaller than the traditional OCGPMP. Simulation and experiment results prove the new method can effectively restrain the effect of spectrum overlap, and improve the measurement accuracy more than 1.74 times.