反射式光纤电流互感器光波偏振态相互转换过程中的误差特性

Error Characteristics in Mutual Conversion Process of Reflective Fiber Optic Current Transducer’s Optical Polarization State

反射式光纤电流互感器是建立在光波偏振理论基础上的光学精密仪器,光波线偏振态与圆偏振态相互转化过程中/4波片、光纤感应头、反射镜等关键部件均会导致光波偏振误差。非理想的光波偏振特性引起光波偏振态随机耦合误差,造成偏振光波之间的串扰,导致光纤电流互感器测量精度误差。针对光纤电流互感器光波线偏振态与圆偏振态相互转化过程中的光波偏振误差特性,采用庞加莱球理论及Jones矩阵建立光纤电流互感器光波偏振模型,分析光纤电流互感器中线偏振态及圆偏振态演变过程;以光纤电流互感器光波偏振模型为基础,研究/4波片、90°相位延迟、传感光纤双折射、反射相位等主要环节对光纤电流互感器测量精度及线性度的影响,仿真并量化各种误差对R-FOCT性能的影响。

Reflective fiber optic current transducer(R-FOCT) is a kind of precision instrument based on optical polarization and optical interference theory.The key optical components in R-FOCT show error characteristics in conversion between linear polarization state and circular polarization state,including quarter-wave retarder,sensing head and mirror,which induces linearly polarized light wave in polarization maintaining fiber and circularly polarized light wave in sensing fiber to be elliptically polarized light wave.Then nonreciprocal phase shift induced by magnetic field of the current is interrupted by wrong polarization state.Focused on polarization error characteristics during mutual conversion process in fiber optic current transducer,optical polarization error models are built by using Jones matrix and Poincare sphere respectively,investigated the influence of several key error factors on measurement accuracy and linearity of scale factor,including phase delay in quarter-wave retarder,birefringence in sensing head and mirror reflection phase shift error.Finally,the proposed methods are verified by simulation test,and scale factor error characteristics of R-FOCT related with optical polarization errors were quantified.The results verify the feasibility of the proposed research scheme.