摘要
采用Fourier变换轮廓术进行 3D面形测量时 ,被测物体的高度变化受到测量范围的限制。当高度变化超过FTP的测量范围时 ,由于阴影和频谱混叠 ,无法实现正确的三维重建。在正交光轴测量系统中避免阴影和频谱混叠 ,我们采用减少成象光轴和投影光轴之间的夹角的方法避免阴影 ,由于成象光轴和投影光轴之间夹角越小 ,测量精度越低 ,为了保证FTP的测量精度 ,增加投影到被测物体上的条纹数。当CCD的分辨率没有提高时 ,一个条纹中的采样点数减少 ,当抽样点数不满足要求时 ,又会引起另一种频谱混叠 ,即周期之间的频谱混叠。本文采用交织抽样方法消除Fourier变换轮廓术中周期间的频谱混叠 ,计算机模拟实验证实了该方法的有效性。
Fourier transform profilometry(FTP) is a popular method to measure 3D object.The slope of the height variation of the measured object must be limited to separate fundamental frequency component form others.If the height variation exceeds the maximum measurement range of the FTP,the correct phase retrieval cannot be obtained because there are shadows in the fringe pattern and the fundamental frequency component overlaps the other components.In a crossed optical axes system for FTP,a smaller included angle between axis of the projection and the detection system is set to avoid shadows and the frequency alias.Because the smaller the included angle is,greater the errors occur in restored object,in order to eliminate the errors resulting from the smaller included angle,we project a dense grating image onto a object.When there is not a high resolution CCD to record the deformed fringe,the subsampled finge is obtained.The theory for microscanning to reduce frequency alias is analyzed.Computer simulations have proved our analysis.
出处
《激光杂志》
EI
CAS
CSCD
北大核心
2000年第5期24-26,共3页
Laser Journal
基金
国家自然科学基金资助项目
