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针对微推力测量中电容位移传感器需要频繁标定非线性误差的问题,提出了一种基于激光干涉的现场标定方法。标定原理为:在直线位移台上同时调节可动角隅棱镜与测量目标的位置,进而改变干涉光路光程差及电容位移传感器极板间距,以激光干涉测量结果为基准,采用线性拟合方法,对传感器非线性误差进行标定。搭建了基于常用光学元件的干涉光路,对应用于微推力测量中不同量程的传感器进行标定。在分析干涉光强变化特点的基础上,确定了干涉条纹数计算方法,得到干涉光路的位移测量精度为66.5nm。实验验证了该校准装置的实用性和准确性,最后对标定结果、传感器输出非线性误差以及影响激光干涉测量精度的主要因素进行了分析,得到激光干涉测量总误差为67.2nm。
Aiming at the problem that the capacitive displacement sensor needs to calibrate the nonlinear error frequently in the micro-thrust measurement, a field calibration method based on laser interference is proposed. The principle of calibration is to adjust the positions of the movable corner cube and the measurement target simultaneously on the linear displacement stage to change the optical path difference of the interference optical path and the distance between the electrode plates of the capacitance displacement sensor. Based on the laser interference measurement results, a linear fitting method , Calibration of sensor nonlinearity error. The interference optical path based on common optical components is built, and the sensors used in different ranges of micro-thrust measurement are calibrated. Based on the analysis of the characteristics of the interference light intensity, the calculation method of the interference fringe number is determined, and the displacement measurement accuracy of the interference light path is 66.5nm. The experiment verifies the practicability and accuracy of the calibration device. Finally, the calibration results, the nonlinear error of the sensor output and the main factors affecting the accuracy of the laser interferometry are analyzed. The total error of the laser interferometry is 67.2nm.