针对传统光栅干涉仪中测量范围和分辨率难以同时提高的问题,提出利用单根大长度、低线数光栅实现大量程、高分辨率位移测量的方法。首先利用长度400mm,栅距10μm计量光栅的±5级衍射光生成条纹图,实现了条纹的10倍光学细分。然后提出一种基于傅里叶变换时移特性的条纹细分新方法,利用相邻两帧条纹图同一位置处相位的变化实现了高达1000倍的条纹电子细分。在此过程中,针对能量泄漏对傅里叶变换法相位提取精度的影响,提出条纹图整周期裁剪的方法,使条纹细分精度至少可达到1/1000条纹周期。仿真和实验结果表明,系统具有纳米级的分辨率和优于10nm的测量精度。

Since both the measuring range and the resolution of a traditional grating interferometer were difficult to be improved simultaneously,a grating interferometry based on a single long metrology grating was presented.Firstly,an interferogram was generated by interference between the ±5 orders beams diffracted by the grating.The length of the grating was 400mm and its pitch was 10μm.The optical fringe multiplication achieved was 10.Then,a fringes subdividing method based on the time-shift property of Fast Fourier Transform (FFT) algorithm was developed.By calculating the phase change of the fringes at a certain position between two sequential acquisition interferogram,the fringes were subdivided electronically and the subdividing multiple was as high as 1000.During this course,the effect of energy leakage on the phase-extraction precision of FFT was suppressed by tailoring the acquisition interferogram into a few full-multiples of the fringes.The resulting subdividing precision could reach at least 1/1000 period of the fringes.Simulation and experimental results show the system resolution is 1nm and measurement precision is less than 10nm.