双频投影条纹相位展开方法的改进

Improvement of phase unwrapping method for dual-frequency projection fringe

为解决双频外差法展开条纹相位中出现跳跃性变化的问题,提出了一种改进方法。首先,根据外差原理计算出条纹级数的小数部分,再由该条纹级数对应频率的光栅条纹的相位主值计算出当前小数部分的实际值。然后,根据相位主值自身误差设置判定阈值,并用该阈值对上述计算值与实际值的差值进行判断。最后,根据判断结果对中间参量的周期次数进行加或减的调整,以校正绝对相位。通过在仿真双频条纹图案的相移图中加入不同均值和方差的高斯噪声,对比校正前后的相位图,分析了改进方法对相位跳跃性误差的校正率,并通过样件实测实验来验证该方法的实用效果。实验结果表明,该改进方法对绝对相位跳跃性误差的校正率可达90%以上,具有较强的抗噪性和实用性。

To address the problem of abrupt changes during the phase unwrapping of fringes using the dualfrequency heterodyne method,we proposed an improved method in this study.First,the fractional part of the fringe order at a frequency was calculated based on the heterodyne principle,and the actual value of the current decimal part was calculated based on the phase principal value of the grating fringe corresponding to the frequency of the fringe order.Second,the difference between the decimal parts of the above two values was determined using a set threshold based on the inherent error of the phase principal value.Finally,the absolute phase was corrected by adding or subtracting the cycle number of the intermediate parameter based on the determination results.By adding Gaussian noise with different mean values and variances to the phase shift diagram of the simulated dual-frequency fringe pattern,and comparing the phase diagrams before and after correction,the correction rate of the improved method for phase jump errors was analyzed.In addition,the practical effect of the method was verified through actual measurement experiments of samples.The experimental results indicate that the improved method yields a correction rate of over 90% for absolute phase jump errors,with a high practicability and immunity to noise.