Both the analysis of phase errors which occur at the abrupt discontinuities in the profilometry based on firinge projection and the identification method are presented in this paper. The sampling effect of CCD will cause a dilution of accuracy, especially at abrupt discontinuities on the object surface. We analyze the relationship among the phase, the height and the equivalent wavelength. By viewing the phase as the argument of a vector, we find out that, CCD sampling introduces error into the measurement, and the phase is nonlinear to the equivalent wavelength. Therefore Temporal Phase Unwrapping (TPU) is introduced into the measurement to identify the abrupt discontinuities. Computer simulations and practical experiment validate the feasibility of this method. The study provides the theoretical support for the reduction of errors caused by CCD sampling.%本文分析了基于结构光投影的不连续物体测量中CCD采样引入的相位误差,并提出了鉴别错误相位点的方法.在物体表面不连续处,由于CCD采样的影响相位测量将出现较大的误差.本文从相位、高度和等效波长的关系出发,将相位看作矢量辐角,发现在物体表面不连续区域处CCD的采样使得相位测量值与等效波长呈非线性关系,从而降低了测量精度,甚至出现错误测量结果.本文引入时间相位展开(TPU)用来鉴别这些错误相位.文中给出了理论分析和实验,结果证明分析的正确性和鉴别方法的可行性,可以为减小CCD采样导致的局部误差提供分析依据.
展开▼
