为了精确控制 FSM系统中平面反射镜的偏转角度，研制了专用型光栅测微仪对其进行位置测量，以实现系统的闭环控制。在明确了 FSM系统对测微仪应用需求的基础上，根据其技术原理，对光栅测微仪的小型滑轨、标尺光栅图案、指示光栅图案、绝对零位编码、指示光栅移相以及接触探头分别进行了设计与选择。经精密加工、装配、调试后，所得光栅测微仪的测量范围为 ±2.5 mm，响应频率为 1 000 Hz，全行程测量精度优于 2 μm，测量分辨力优于 0.06 μm，并能提供绝对零点位置。工程应用实践证明：该光栅测微仪具有高精度、高分辨力、高可靠性的特点，满足 FSM系统的使用要求。

In order to control rotary angle of reflector accurately in the Fast-steering Mirror (FSM) system, a specialized grating sensor used for measuring the position of reflector to offer feedback information for servo controlling system was designed. On the basis of application requirements of grating sensor in the fast-steering mirror system, small slip track, pattern of scale gratings, pattern of index gratings, form of absolute zero code, moving index gratings and styles of measure probes were designed and chosen respectively on technology principle of grating sensor. Then, the grating sensor was tested after finely manufacturing, assembling and adjusting. The results show that measure length of the grating sensor is about ± 2.5 millimeters, its response frequency is about 1 000 Hz, its measure error is less than 2 microns, its measure differentiate is less than 0.06 microns and it can export absolute zero. Applied results of the grating sensor show that the sensor which has high precision, excellent resolution and powerful dependability can satisfy application requirements of the fast-steering mirror system.