基于激光的回馈效应可实现光学材料应力分布的测量,而系统外腔镜的非线性运动会引起测量结果的误差,影响系统的精度.利用高精度Nd:YAG激光回馈干涉仪对外腔镜的位移随时间的变化进行测量,采用高次拟合的方式得到位移与时间函数关系,并利用三镜腔等效模型的调谐曲线方程,对非线性运动引入的应力测量误差进行计算,实现对系统精度的修正.结果表明:外腔镜运动方向不同,引起的误差呈现相反的变化趋势:将不同方向的测量结果进行平均,可减小系统的测量误差.分析了外腔镜非线性运动带来的误差对系统测量精度的影响,提出了测量误差修正方法,对提高系统的测量精度具有重要意义.
Stress distribution of optical materials can be measured by using the laser feedback effect. Owing to the nonlinear movement of the feedback mirror, the result accuracy of the system will decrease. In this work, we measure the displacement of the feedback mirror by using a high precision quasi-common-path laser feedback interferometry. The displacement-time function is obtained by a high-end fitting method. The stress measurement error induced by the non-linear movement of the feedback mirror is calculated according to the displacement-time function and a three-mirror cavity equivalent model, and the correction for the system accuracy is achieved. The results show that the different movement direction of the feedback mirror gives rise to an opposite variation trend of error. Measurement error can be reduced by averaging the results in different directions. In the study we analyze the influence of the non-linear movement of the feedback mirror on the measurement accuracy, and a method of improving the error is proposed. This method is significant for correcting the measurement results and improving the accuracy.