相位测量系统中投影仪输出与CCD输入变形条纹光强之间的非线性导致频谱混叠,影响测量精度,为了消除他们之间的非线性关系,提高相位测量精度,分析了系统非线性产生的基本原因,提出了一种基于系统非线性校正与滤波的相位测量方法.首先校正由投影仪中伽马畸变产生的系统非线性,然后采用低通滤波器对校正后输出的频谱进行滤波,只保留频谱中的基频成份,最后采用四步相移法对变形条纹进行相位测量.MATLAB仿真与实际实验结果表明,所提方法的系统非线性校正与滤波效果较好,有助于提高相位测量精度.

The nonlinearity between projector output and CCD input deformed fringe intensity in phase measurement system results in spectrum aliasing and affects measurement accuracy. In order to eliminate the nonlinearity relationgship between them and improve phase measurement accuracy, the basic causes of system nonlinearity are analyzed, and a new phase measurement method based on system nonlinearity correction and filtering is proposed. Firstly, the system nonlinearity caused by the gamma distortion in the projector is corrected. Then, the output spectrum is filtered by low-pass filter, only the fundamental frequency component of the spectrum is retained. Finally, the phase measurement of deformed fringes is carried out by four-step phase-shift method. The results of MATLAB simulation and practical experiment show that the proposed method has better effect of system nonlinearity correction and filtering, and is helpful to improve the phase measurement accuracy.