为提高对自由曲面对象细节的分辨能力,抑制解相产生的跳跃性误差,并减少正确解相的充分条件,提出基于多频外差的全频解相方法。首先,通过标准四步相移法求解包裹相位;然后,使用全频解相法,通过绝对相位与光栅节距之间的关系,转换不同节距的光栅包含的细节信息,从而提高解相相位细节的精度。相比现有方法,所提方法抑制解相产生的跳跃性误差的约束更少。仿真结果表明,所提方法解相后无跳跃性误差,且无需额外的误差校正。实验结果表明,所提方法的三维重构精度更高,且重构表面更平滑,细节更清晰。相比现有方法,所提方法的解相误差标准差减小44%。

In order to improve the ability of recognizing the details of the measured free-form surface, restrain the jumping error caused by the processing of phase unwrapping, and reduce the sufficient conditions for the correct phase unwrapping, a full-frequency phase unwrapping algorithm based on multi-frequency heterodyne is proposed. First, the standard four-step phase shifting algorithm is used to solve the wrapped phase. Then, using the full-frequency phase unwrapping algorithm, the details contained in the fringe pattern with different pitches are converted by the relationship between the phase and the fringe pitch to improve the accuracy of the unwrapped phase details. Compared with the existing method, less constraints are derived in order to restrain the jumping error caused by the processing of phase unwrapping. Simulation results show that the proposed method has no jumping error after the phase unwrapping, and no additional error correction is needed. Experimental results verify that the three-dimensional reconstruction has higher precision, the reconstructed surface is smoother and the details are clearer. Compared with the existing method, the standard deviation of phase unwrapped error of the proposed method is reduced by 44%.