Electricity: measuring and testing – Particle precession resonance – Using optical pumping or sensing device
Patent
1987-04-30
1988-10-25
Tokar, Michael J.
Electricity: measuring and testing
Particle precession resonance
Using optical pumping or sensing device
324301, G01R 3326
Patent
active
047806729
ABSTRACT:
A helium magnetometer includes a helium cell containing helium, preferable .sup.4 He. A solid state laser strikes the helium cell at one end with a laser having a wave length of 1082.91 nm in the embodiment of a .sup.4 He cell. The helium atoms precess at known frequencies for different magnetic fields. The transparency of the helium cell at 1082.91 nm with .sup.4 He is a function of the resonance of the atoms within the helium cell. A radiation detector positioned on a second end of the helium cell opposite the end where the laser strikes detects the laser when transmitted through the helium cell and produces an electrical signal in response to the transmitted laser. The resonance of the helium cell is enhanced by a Voltage Controlled Oscillator, VCO, which provides a variable output frequency to a pair of coils positioned on the sides of the helium cell and electrically connected to the VCO to receive the variable output frequency. The pair of coils produces a variable magnetic field at the precession frequency that is mathematically related to the magnetic field that is being measured and thus enhances the precession of the atoms within the helium cell. A feedback loop includes a demodulation circuit that is electrically connected between the radiation detector and the VCO and demodulates the electrical signal from the radiation detector to produce a drive voltage for driving the VCO.
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Comfort James T.
Grossman Rene E.
Sharp Melvin
Texas Instruments Incorporated
Tokar Michael J.
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