一种改进的消零频傅里叶变换轮廓术  

An improved Fourier transform profilometry for zero frequency elimination

作　　者：周灿林[1] 杨允鑫[1] 司书春[1] 徐建强[1] 雷振坤[2] 

机构地区：[1]山东大学物理学院,山东济南250100 [2]大连理工大学工程力学系,辽宁大连116024

出　　处：《光电子．激光》2014年第6期1140-1145,共6页Journal of Optoelectronics·Laser

基　　金：国家自然科学基金(11172054);山东省科技攻关(2007GG30004010;2011GGX10125)资助项目

摘　　要：为提高傅里叶变换轮廓术(FTP)的测量精度和范围,提出了一种改进的消零频FTP。将两幅随机相移正弦条纹通过DLP投影仪投射到待测物体上,由CCD相机采集受物体形貌调制的变形光栅条纹图,将采集的两幅条纹图相减得到无零频的条纹差图。对条纹差图进行快速傅里叶变换(FFT)后,通过简易滤波器提取基频成分,将其与彩色条纹或复合光栅投影相结合,可实现单次投影。理论和实验证明了本方法的可行性。Deformed fringes often contain fundamental frequency information degraded by background intensity information in structured light projection of three-dimensional（3D）surface shape measurement of complex tested object.The background intensity information needs to be removed in order to avoid frequency aliasing,get fundamental frequency component and enhance measurement accuracy and range in Fourier tansform profilometry（FTP）.An improved FTP is proposed to eliminate the zero frequency component.Firstly,two phase-shifted randomly sinusoidal fringe patterns are projected onto the tested object by digital-light-processing（DLP）projector.The fringe pattern modulated by the object′s surface is captured by a CCD camera.Secondly,the difference of two fringes is obtained after numerical processing.The standard fast Fourier transform（FFT）is applied to fringe difference.Thus the simple filter can be designed to extract the fundamental frequency without zero component in spectral domain.A simple fringe pattern projection can be accomplished if the proposed method is combined with the color or composite grating.Finally,facial mask is used for specimen,and the experimental evaluation is conducted to prove the validity and performance of the method.The experimental results are analyzed and compared with those of the traditional method.The effectiveness and superiority of the proposed method are demonstrated.

关 键 词：相移法 傅里叶变换轮廓术(FTP) 相位测量轮廓术(PMP) 滤波 

分 类 号：O348[理学—固体力学] O43[理学—力学]