多频光栅物体高精度廓形三维测量及重建研究

针对目前实际系统中，由于噪声的存在，单频光栅逐点解相时无法获得全场相位值，导致对廓形复杂、体积小物体的重建精度低，提出多频结构光栅投影实现体积较小、形貌复杂物体的高精度重建。系统算法基于随时间序列变化改进的四步相移法对多频光栅进行解相，多频光栅解相是对每种频率的光栅单独展开相位，每种频率的光栅解相是逐点进行的，单频光栅中因噪声得到不连续的相位可通过其他频率光栅拟合修补，得到一个全场范围内连续的相位。经实验单频结构光测量体积小、形貌复杂物体的误差范围为0.1 mm～0.5 mm，而文中所提出方法精度达到了0.03 mm～0.05 mm，该方法精度提高了10倍左右。

Research on 3D measurement and reconstruction of high-precision profile of multi-frequency grating object

In the current practical system, due to the existence of noise, the full-field phase value cannot be obtained when the single-frequency grating is phase-resolved point by point, which leads to the low reconstruction accuracy of small objects with complex profiles. A multi-frequency grating projection method was proposed to realize the high-precision reconstruction of the objects with small volume and complex morphology. The system algorithm decomposed the multi-frequency grating based on the improved four-step phase-shifting method which changed with time series. The multi-frequency grating decomposition separately expanded the phase of each frequency grating, and the grating decomposition of each frequency was carried out point by point. The discontinuous phase in the single-frequency grating due to noise could be repaired by fitting other frequency gratings, and a continuous phase in the whole field could be obtained. Experimental results show that the error range of single-frequency structured light is 0.1 mm～0.5 mm for measuring small and complex objects, while the precision of our method is 0.03 mm～0.05 mm, which can be improved by about 10 times.