Abstract: Apparatus comprises a tuning fork having first and second tines, a first magnet disposed on the first tine, and a second magnet disposed on the second tine. In one embodiment the magnets comprise permanent magnets; in another they comprise electromagnets. In a preferred embodiment the magnets have magnetic moments oriented essentially parallel to the axis of the tines and anti-parallel to one another. In operation, the apparatus is made to oscillate at or near its resonant frequency, and in the presence of a magnetic field a parameter of the oscillation (e.g., its frequency, phase or amplitude) is altered in a fashion that allows the magnitude or direction of the magnetic field to be determined. In a preferred embodiment, the tuning fork is disposed within a vacuum enclosure, which increases the Q of the apparatus.

Abstract: Apparatus comprises a tuning fork having first and second tines, a first magnet disposed on the first tine, and a second magnet disposed on the second tine. In one embodiment the magnets comprise permanent magnets; in another they comprise electromagnets. In a preferred embodiment the magnets have magnetic moments oriented essentially parallel to the axis of the tines and anti-parallel to one another. In operation, the apparatus is made to oscillate at or near its resonant frequency, and in the presence of a magnetic field a parameter of the oscillation (e.g., its frequency, phase or amplitude) is altered in a fashion that allows the magnitude or direction of the magnetic field to be determined. In a preferred embodiment, the tuning fork is disposed within a vacuum enclosure, which increases the Q of the apparatus.