Sensor Design for a Current Measurement System with High Bandwidth and High Accuracy Based on the Faraday Effect

Abstract

This paper presents the design of the optical system of a current sensor with a wide bandwidth and a high accuracy. The principle is based on the Faraday effect, which describes the effect of magnetic fields on linearly polarized light in magneto-optical material. To identify suitable materials for the optical system the main requirements and specification are determined. A theoretical description of the optical system shows a maximal applicable magnetic field frequency due to the finite velocity of light inside the material. Hence, the theoretical characterisation of the system implies practical boundaries on the optical material and its specifications. Finally, two different magneto-optical crystals, Terbium Gallium Garnet and Cadmium Manganese Telluride, are investigated, assembled and put into an optical system prototype.