傅里叶变换轮廓术中抑制零频的新方法  

New Method to Eliminate Extension of Zero Component in FTP

作　　者：陈文静[1] 苏显渝[1] 曹益平[1] 向立群[1] 

机构地区：[1]四川大学光电科学技术系,四川成都610064

出　　处：《中国激光》2004年第6期740-744,共5页Chinese Journal of Lasers

基　　金：国家自然科学基金 (6 0 1770 0 1);四川省应用基础研究基金 (0 1gy0 5 1 0 7)资助项目。

摘　　要：基于条纹投影的傅里叶变换轮廓术 (FTP)是一种非接触、快速的光学三维面形测量方法。将短时傅里叶变换引入傅里叶变换轮廓术中 ,通过合适滑动窗口把变形条纹分成许多局部条纹段。计算每一个局部变形条纹的归一化傅里叶谱 ,提取零频分量 ,从中重构出变形条纹的零频分量。再计算原变形条纹的归一化傅里叶谱 ,并从中减去零频分量 ,以达到利用一帧变形条纹就可以抑制或消除零频分量对傅里叶变换轮廓术测量的影响 ,使得携带被测物体高度信息的基频分量的扩展几乎可以达到零频 ,而不发生混叠 ,相当于达到了π相移技术消除零频的效果。同采用π相移技术来消除背景光场的改进傅里叶变换轮廓术方法相比 ,此新方法仅需要对CCD获取的一帧条纹图进行处理 ,测量装置简单 ,随着计算机处理速度的提高 ,使傅里叶变换轮廓术能真正发挥其快速测量的优势。Fourier transformation profilometry (FTP) is a non-contract and high speed optical 3-D measurement method. Here, a short-time Fourier transform is introduced into FTP to extract zero component included in deformed fringe pattern only employing one frame deformed fringe pattern. In this method, a window function is used to scan through whole deformed fringe image from left-top to right-bottom to form many partial fringe patterns. For each partial fringe, its normalized Fourier spectrum is calculated, the zero components are extracted and superimposed to restore the zero component. Then the normalized Fourier spectra of original deformed fringe pattern is calculated. Finally the zero component is subtracted from Fourier spectra of deformed fringe pattern. Eliminating zero component can extend the measuring range of Fourier transform profilometry to nearly three times of that of the traditional FTP as π phase-shifting technique does. Experiment verifies that it is an efficient method to extend measuring range and keep measuring speed. Compared to π phase-shifting technique, only one frame deformed fringe pattern is needed to eliminate the zero component. The setup is simple because of no phase shifting device needed.

关 键 词：信息光学 傅里叶变换轮廓术 短时傅里叶变换 频谱混叠 

分 类 号：O438.2[机械工程—光学工程]