Spherical shell fibre optic magnetic field sensors and magnetometers and magnetic gradient detectors incorporating them
First Claim
1. A magnetic field sensor with an omnidirectional response comprising a magnetically sensitive spherical shell formed by winding a length of magnetically sensitised single mode optical fibre in substantially random directions to produce a spherical shell shape, the fibre having a coating of a magnetostrictive material serving to magnetically sensitise it, disposition of the sensor in a magnetic field causing a corresponding length change of the optical fibre which can be detected interferometrically.
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Abstract
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.
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Citations
8 Claims
- 1. A magnetic field sensor with an omnidirectional response comprising a magnetically sensitive spherical shell formed by winding a length of magnetically sensitised single mode optical fibre in substantially random directions to produce a spherical shell shape, the fibre having a coating of a magnetostrictive material serving to magnetically sensitise it, disposition of the sensor in a magnetic field causing a corresponding length change of the optical fibre which can be detected interferometrically.
- 3. A magnetometer comprising an all fibre Mach-Zehnder interferometer in one arm of which is connected a magnetic field sensor comprising a magnetically sensitive spherical shell formed by winding a length of magnetically sensitised single mode fibre in substantially random directions to produce a spherical shell shape, the fibre having a coating of a magnetostrictive material serving to magnetically sensitise it, disposition of the sensor in a magnetic field causing a corresponding length change of the optical fibre in the one arm of the interferometer.
Specification