Fiber-optic magnetic gradiometer utilizing the magnetic translational force

A fiberoptic AC/DC magnetic gradiometer utilizing magnetic translational force is proposed, and its working principle is verified. The minimum gradient of an AC magnetic field of 4*10/sup -2/ is detected with 100 mm of Sm-Co-coated sensor fiber built into an interferometer. This gradiometer is intrinsically insensitive to spatially uniform magnetic fields but is sensitive to their gradients. Therefore, the dynamic range and S/N ratio of measurements with the proposed sensor are not restricted by the magnitude of background magnetic field, including the geologic magnetic field. Spatial resolution is <1 mm.<
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