Electrical current sensors based on transparent magnets

A brief review of the latest developments on optical current measurements based on the Faraday effect is presented. In all existing magnetooptical current transformers the main measured parameter is the polarization state of the light transmitted by a sensor element. A new transformer in which the measured parameter is the geometrical position of the boundary between domains with opposite magnetizations is described. In a wide frequency band, including dc currents, the measurement results are a linear function of the measured current and are not affected by temperature changes and mechanical factors.