高精度干涉式光纤陀螺热漂移分析

Analysis of thermal drift in high performance interferometric fiber-optic gyroscopes

为了改进干涉式光纤陀螺的测量精度和温度性能,建立了该仪器输出偏置的解析模型。通过把光纤双折射这一从未被考察过的相位微扰与其它已知误差源进行线性叠加,该模型首次显式地把陀螺性能直接与光纤的力学、光学、热学和几何参数联系起来。利用该模型对常用于10-3 deg/h精度量级光纤陀螺的64层四极对称环圈进行计算,结果表明,保偏光纤所固有的高双折射及其温度涨落对陀螺输出偏置及其热漂移的影响分别在10-3 deg/h和10-2 deg/h量级,而过去研究较多的单模光纤中的舒普效应和热致光弹效应的影响分别在10-4 deg/h和10-3 deg/h量级。该模型表明保偏光纤所固有的高应力双折射是干涉式光纤陀螺的主要误差源,同时较为完备地描述了光纤陀螺中源于光纤性能的误差,也解释了该误差对光纤双折射的非线性依赖。

In order to improve accuracy and thermal performance,an analytical model of thermal-induced drift in interferometric fiber-optic gyroscopes containing all of the known phase perturbations is proposed.Unlike in previous studies,by incorporating fiber birefringence as one of the model′s known error sources,the proposed model directly relates gyro performance to mechanical,geometric,thermal and optical parameters in coiled fibers.The influence of these parameters on the gyro drift was numerically calculated according to the presented model.Measurement results of a quadrupole coil within gyroscopes at 10-3 deg/h accuracy confirmed that the bias and its thermal drift induced by the intrinsic high birefringence and its thermal fluctuation in polarization-maintaining fibers are in the order of 10-3 deg/h and 10-2 deg/h.The results also confirmed that the thermal drift induced by the Shupe effect and the photoelastic effect in single-mode fibers are in the order of 10-4 deg/h and 10-3 deg/h,respectively.The proposed model shows that the highly stress-induced birefringence in polarization-maintaining fibers is a dominant source of error that results in bias and thermal drift in high performance interferometric fiber-optic gyroscopes.The model also comprehensively describes how the errors rise from fiber performance in fiber-optic gyroscopes and explains the non-linear dependence that the gyroscopic error has on fiber birefringence.