Current Measuring Probe Using Optical Fiber.

The feasibility of devising a current measuring probe using a monomode optical fiber placed in a Sagnac interferometer is considered here. The physical effect on which its operation is based is the Faraday magneto-optic effect, a nonreciprocal phenomenon - like inertial rotation - that makes it possible to circumvent numerous reciprocal kinds of perturbations such as pressure or temperature. Problems connected with the polarization of light and maintaining it inside the active part of the sensor are discussed by the authors, who provide an experimental verification of the principles investigated.