Temperature compensation in magnetooptic AC current sensors using an intelligent AC-DC signal evaluation

The basic theory of birefringent Faraday materials is well known, but some very interesting conclusions from this theory concerning the application of Faraday materials to magnetooptical current sensing have not been drawn yet. In this paper a general theoretical description of current sensors using homogeneous linear birefringent Faraday materials is given. The theoretical description is used to develop practically applicable methods of compensating the temperature drift caused by the linear birefringence in the Faraday material. Experimental results for a glass ring sensor and a sensor using an annealed fiber coil are given. Accuracies up to only 0.2% error over a temperature range from -20-80°C have been achieved