Reflectometric fiber optic sensor for distributed measurement of intense magneto-static fields

A novel, distributed fiber optic sensor for the vector characterization of static magnetic fields is presented. The sensor is based on Faraday rotation and on the analysis of the state of polarization of the Rayleigh backscattered field. Specifically, the sensor measures the projection of the magnetic field vector in the direction of the fiber. By exploiting this feature and properly arranging the fiber, multi-dimensional maps of the magnetic field can be built. Owing to the faintness of Faraday rotation in standard optical fibers, the proposed sensor is most suited for intense magnetic fields. Experimental results are presented to show the successful measurement of the magnetic field of a 1.5-T magnetic resonance imaging scanner, with a relative accuracy of about 7% and a spatial resolution (along the fiber) of 3 cm.