High precision optical current measurement system based on the faraday-effect with a large bandwidth

In this paper, a high dynamic, high precision optical current measurement system based on the Faraday-effect is presented. First, the sensor concept is explained and different sensor constructions are analyzed. Then, an implementation of the concept based on a rare-earth iron garnet film is investigated. This measurement system uses multiple signal processing channels to increase the signal-to-noise ratio. Furthermore, the range of the rotation of the polarization plane exceeds 90 ° and therefore requires a counting mechanism to count the number of rotations. Finally, the precision of the presented system is analyzed. The precision is determined to be 4.9 ppm for a rotation range of 3300°.