作为纳米位移测量技术领域的关键解决方案之一，干涉型光栅位移测量系统具有高精度、高分辨率、小体积的特点。干涉型光栅位移测量系统中采用的干涉光来自光栅的衍射，所以系统对光栅的偏摆角度较为敏感，装调难度大。为此，研制了一种对称式双光栅干涉位移测量系统，基于光学多普勒频移效应和圆偏振光干涉等原理实现高精度位移测量，系统对位公差小，装调简便。性能测试结果表明，该系统的实测分辨率为0.8 nm，重复性为1.4 nm；在1~14.5 μm的位移范围内校正前系统测量精度为15.4 nm，采用系统运动轨迹误差校正后精度为5.5 nm，进一步采用周期性误差校正后精度达到1.4 nm。

As one of the key technical solutions for nano-displacement measurement, the interferometric grating displacement measuring system has such characteristics as high precision, high resolution and small size. Because the interferent light beams come from the diffraction of gratings, the system is sensitive to gap and rotational tolerance between the optical head and scale, and is difficult to align. A symmetrical double-grating interferometric displacement measuring system, which achieves high-precision displacement measurement, is developed based on optical effect of Doppler shift and circularly polarized light interference. The system has small tolerance and simple alignment. The performance tests show that the developed system has the actual resolution of 0.8 nm, repeatability of 1.4 nm. In the movement range of 1-14.5 μm, its accuracy without correction is 15.4 nm, and the accuracy with trajectory error correction is 5.5 nm. After periodic error correction, the accuracy can be improved to about 1.4 nm.