Temperature and/or electrical intensity measuring apparatus based on the Faraday effect

An apparatus for measuring the temperature in the vicinity of an electrical conductor, and/or the amount of electrical current through such conductor, said measuring being based on the Faraday effect using magneto-optical means, said apparatus comprising a probe constituted by an optical fibre wound in the general form of a solenoid, said conductor lying along the longitudinal axis of the solenoid, and two optical fibre strands connecting respective ends of the probe to an inlet coupled to a polarized light source and an outlet coupled to first computer means for measuring the rotation angle of the polarizaton plane of the light between its entrance into the inlet optical fibre strand and its exit from the outlet optical fibre strand, the optical fibre portion constituting the probe being twisted about its longitudinal axis in a single random direction, the said two optical fibre strands connected to the probe being twisted in opposite directions relative to each other, the number of twisting turns to the right of one of the said two strands being equal to the number of twisting turns to the left of the other of said two strands, said apparatus further comprising, at the outlet end of said outlet optical fibre strand, a semi-transparent plate on the outlet face of the said outlet fibre strand able to reflect along a return path back into the outlet strand at least part of the light beam towrds the inlet face of the inlet strand, said apparatus further including at said inlet face another semi-transparent plate, inclined by 45.degree. to the incident light beam, and able to direct part of the return path light beam towards second computer means for measuring the rotation angle of the polarization plane of the light from its entrance into the system, and third computer means connected to said first and second computer means for generating at its output an expression indicative of the current flow through said conductor and/or the temperature in the vicinity thereof.