基于双向吸收光谱精准标定的光频扫描干涉绝对测距

Absolute ranging of optical frequency scanning interferometry based on accurate calibration of bidirectional absorption spectroscopy

本文研究了光频扫描干涉绝对测距的长度基准精准标定方法.利用气体吸收光谱在线标定测距系统中作为长度基准的延时长光纤光程,并提出利用加权线性最小二乘方法解决不同吸收谱峰不确定度的差异.针对吸收光谱标定光纤光程重复精度低的问题,提出了利用双向吸收光谱特征融合的方法提升光纤光程标定精密度.针对吸收谱峰绝对光频准确性不足的问题,提出单一吸收光谱比例系数的标定方法,相较于逐一校准谱峰光频的思路更为简单直接,提升了光纤光程标定准确度.为验证上述方法的有效性,分别进行了重复精度评估实验、比例系数标定实验以及精度比对实验.实验结果表明,标定164 m光纤光程的标准差为10-30μm,在系统温度上升及温度稳定条件下,0-10 m及0-15 m的测量范围内,测距标准差不大于5μm,测距比对残差不大于±4μm,显示了该系统良好的测距性能.

Accurate measurement of length is an important foundation for ensuring the quality of advanced manufacturing equipment.In recent years,absolute ranging technology represented by frequency scanning interferometry(FSI)has gradually become a widely used ranging method in the manufacturing industry due to its advantages of high precision,high flexibility,and no range ambiguity.To address the repeatability and accuracy of length reference calibration in FSI absolute ranging,this paper proposes a method of accurately calibrating length reference based on bidirectional absorption spectrum feature fusion and proportional coefficient calibration,by using gas absorption spectroscopy to calibrate the delayed long fiber path length as a length reference in the distance measurement system online,and by using weighted linear least squares method to solve the differences in uncertainty among different absorption spectrum peaks.To address the problem of low repeatability in optical fiber path length calibration by using absorption spectroscopy,a method of utilizing bidirectional absorption spectrum feature fusion is proposed,thereby improving the precision of optical fiber path length calibration.To address the issue of insufficient accuracy in absolute optical frequency of absorption spectrum peaks,a calibration method by using a single absorption spectrum proportional coefficient is proposed.Compared with the idea of calibrating the optical frequency of each peak one by one,this method is simple and direct,thus improving the accuracy of fiber path length calibration.To verify the effectiveness of the above methods,the experiments on repeated precision evaluation,proportional coefficient calibration,and accuracy comparison are conducted separately.The experimental results show that the standard deviation for calibrating the optical path length of 164 m fiber is 10–30μm.Under the conditions of system temperature rise and temperature stability,the distance measurement standard deviations are not greater than 5μm in the measurement ranges of 0–10 m and 0–15 m,and the distance comparison residuals are not greater than±4μm,demonstrating the good distance measurement performance of the system.In the future,we will carry out thermal insulation and temperature control of the gas absorption chamber and the entire ranging optical path,and study the stability of the spectral proportionality coefficient and absorption peaks while controlling external environmental factors.