Spherical shell fibre optic magnetic field sensors and magnetometers and magnetic gradient detectors incorporating them

摘要

A magnetic field sensor is comprised by a length of magnetically sensitized single mode optical fibre wound in substantially random directions on a sphere of non-magnetic material, so that an omnidirectional response is obtained. Specific directionality can be obtained by application of a dc bias field in the desired direction. All three perpendicular components can be measured by applying three perpendicular ac fields at different frequencies. The sensor is intended for use in all fibre Mach-Zehnder interferometer types of magnetometer or magnetic gradient detector, examples of which are described.