High sensitivity gradient magnetometer

Claim 1

A magnetic resonance gradient magnetometer comprising: a. first and second magnetic resonance cells rigidly mounted to a common base separated by a predetermined distance; b. a common pumping light source to provide a beam of pumping radiation; c. means to split the pumping beam from said common pumping source to provide a first pumping beam to said first cell and a second pumping beam to said second cell such that the light received by both said first and second cells is from the same region of said common pumping source whereby any lamp variations will be equally experienced at both cells; d. means to circularly polarize said first and second pumping beams; e. a common readout source of light providing a common read-out beam; f. means to split said common read-out beam into first and second read-out beams and to provide said first and second beams respectively to said first and second resonance cells so as to intersect said cells perpendicular to said first and second pumping beams such that the light received by both said first and second cells is from the same region of said common read-out source whereby any lamp variations will be equally experienced at both cells; g. means to cause said first and second read-out beams to interact with said cells so as to provide an amplitude modulated signal; h. first and second means to detect and provide an output proportional to the intensity of said respective first and second read-out beams after passing through said first and second cells; i. a first set of H1 coils with the axis of said coil parallel to said first read-out beam; j. a second set of H1 coils with the axis of said coils parallel to said second read-out beam; k. first coil driving means to drive said first set of coils, said means being responsive to the output of said first detecting means; l. second coil driving means to drive said second set of coils, said means being responsive to the output of said second detecting means; and m. phase comparator means having the output of said first and second detecting means as inputs and providing an output function dependent on the phase difference of said inputs whereby said output will be functionally dependent on the difference between the magnitudes of the earths magnetic field at said first and second cells.