Distributed fiber optic sensor for mapping of intense magnetic fields based on polarization sensitive reflectometry

We describe a novel distributed fiber optic sensor, which is able to map both strength and orientation of intense static magnetic fields in the area spanned by the fiber. The sensor is based on Faraday rotation and on polarization analysis of the field backscattered by the fiber due to Rayleigh scattering. Owing to a specific theoretical model, it is possible to isolate and measure the effect of magnetic field along the fiber, independently of its intrinsic birefringence. The small Verdet constant of standard silica fibers makes the proposed technique most suited to intense magnetic fields. Two different sensors based on this approach have been built and successfully tested in a 1.5 T magnetic resonance imaging scanner.