提高傅里叶变换轮廓术测量精度的新方法

New method for improving the measuring precision of FTP

在傅里叶变换轮廓术 (FTP)测量方法中 ,成像装置获取受到物体高度调制后的变形结构光场 ,通过傅里叶变换 ,滤波和逆傅里叶变换恢复出物体高度分布。频谱滤波是FTP中很重要的一个过程 ,也是影响FTP测量精度的一个重要因素。通常滤波是手工选择合适的滤波函数和滤波窗口大小 ,窗口太小 ,表示物体细节的高频信息将丢失 ;窗口太大 ,无法消除噪声。本文提出一种新的滤波方法 ,无需手工选择滤波函数 ,可以很好地保留物体高频信息并消除随机噪声 ,从而提高FTP的测量精度。

In Fourier transform profilometry(FTP),projecting a structure field of grating pattern onto a measured object,a deformed fringe pattern is captured.The height distribution of the measured object can be determined by Fourier transform,filtering and inverse Fourier transform.Filtering is an important process in FTP,and it is also an important factor to influence precision.If the size of the filtering window is too small,it is difficult to filter full fundamental frequency.And if the size of the window is too large,it is difficult to eliminate the noise.In this paper,a new filtering method is proposed to overcome those shortcomings,because there is no need to choose a filtering window.This method can keep enough frequency and eliminate the noise.Computer simulations verify that this is an efficient method to improve the measuring precision.