基于长度可变真空腔的激光干涉空气折射率测量误差分析与补偿

Analysis and compensation of the measurement error of air refractive index using a laser interferometer with a variable length vacuum cavity

为了解决基于长度可变真空腔的激光干涉空气折射率测量中透光窗片倾斜和真空腔内残余气压对测量精度的影响,本文分析了真空腔拉伸过程中透光窗片倾斜引入的误差,并提出了透光窗片倾斜误差检测和补偿方法,同时研究了真空腔内残余气压的测量和补偿方法。为了验证所提出方法的可行性,搭建了基于长度可变真空腔的激光干涉空气折射率测量系统,测量结果与Edlén公式结果进行对比。实验结果显示,本系统测量结果与Edlén公式结果具有较好的一致性,在2.2 h和20 min内,两者之间偏差的标准偏差分别为2.34×10^(-8)和2.89×10^(-8),这表明本文所提出的空气折射率测量误差补偿方法是可行和有效的,可应用于激光干涉精密位移测量中空气折射率的实时补偿。

To solve the influences of the tilt of optical windows and the residual air pressure in the vacuum cavity on the measurement accuracy in the laser interferometric air refractive index measurement based on the variable length vacuum cavity,this paper analyzes the error caused by the optical window tilt when the vacuum cavity is pulled.And a method for detecting and compensating the tilt error of windows is proposed.In addition,the method of measuring and compensating the air residual pressure in the vacuum cavity is studied.To verify the effectiveness of the proposed method,a laser interferometric air refractive index measurement system based on the variable length vacuum cavity is constructed,the measurement results with proposed method are compared with the results obtained by Edlén equation.Experimental results show that,the measurement results of the two method are in good agreement.In 2.2 h and 20 min,the standard deviations of the differences between the measurement results of the proposed method and that of the Edlén equation are 2.34×10^(-8)and 2.89×10^(-8),respectively.This indicates that the proposed measurement error compensation method of air refractive index is feasible and effective,which can be applied to the real-time compensation of air refractive index in laser interferometric precision displacement measurement.