基于四象限探测器的线性光学电流互感器

基于径向检偏原理的线性光学电流互感器(OCT)将磁致旋光角转换为同步旋转的光斑图像,通过电荷偶联相机对光斑条纹定位实现电流测量,克服了传统光强检测模式的动态测量范围窄、非线性、光功率依赖性、线双折射干扰和温漂等缺陷。但是其图像检测方法仍然存在成本高、分辨率低、算法误差大等问题,尤其是在小电流测量时误差较大,难以达到S级要求。针对这些问题,提出了一种采用四象限探测器测量光斑图像旋转角的方法并应用于线性OCT中,具有成本低、算法简单、分辨率高、精度高等优点。经过理论分析和实验验证,在±40°磁致旋光角范围内测量分辨率提高了近100倍,测量准确度从0.5级提高到了0.2S级,图像检测单元的成本降低了95%以上。

Linear Optical Current Transducer Based on Four-quadrant Detector

In a linear optical current transducer(OCT)based on the radial grating polarizer detection, the faraday rotation angle is converted into synchronous rotation of a circular facula. Then, a charge coupled device camera(CCDC)is utilized to position the dark stripe of the facula to achieve a real time current measurement. The linear OCT overcomes some issues in the OCT of traditional light intensity detection mode, such as small dynamic measurement range, nonlinear detection, light intensity dependence, linear birefringence and temperature drift etc. However, the linear OCT still has some shortcomings, such as high cost, low resolution, big algorithm error, and not being capable of meeting 0. 2S accuracy class, especially in small current measurement. In order to fix these problems, a four-quadrant detector is employed to sense the rotation angle of the circular facular with the advantages of low cost, simple algorithm, high-resolution and high-accuracy. It has been verified that the resolution of measurement is increased nearly 100-fold by theoretical analysis and experimental derivation in the range of ±40°of the faraday rotation angles. The accuracy is improved from 0. 5% class to 0. 2S, and the cost of picture detection unit is reduced by more than 95%.