Nuclear magnetic resonance gyro

A nuclear magnetic moment alignment device comprising:

• a nuclear magnetic resonance cell;
• a gas or vapor of an optically pumpable substance that possesses a magnetic moment and is capable of being optically pumped, said optically pumpable substance being contained in said cell;
• first and second noble gases, chosen from the class consisting of xenon isotopes having a nuclear magnetic moment and krypton isotopes having a nuclear magnetic moment, and contained in said cell;
• means for applying a steady state magnetic field to said cell;
• and
• means for illuminating said cell with optical pumping light capable of partially aligning in one direction by absorption of said light the magnetic moments of said optically pumpable substance to cause the nuclear magnetic moments of said first and second noble gases to be partially aligned by collisions of atoms of said optically pumpable substance with atoms of said noble gases.

A nuclear magnetic moment alignment device comprising:

• a nuclear magnetic resonance cell;
• a gas or vapor of an optically pumpable substance that possesses a magnetic moment and is capable of being optically pumped, said optically pumpable substance being contained in said cell;
• xenon-129 and krypton-83 gases each having a nuclear magnetic moment and contained in said cell;
• means for applying a steady state magnetic field to said cell;
• and
• means for illuminating said cell with optical pumping light capable of partially aligning in one direction, by absorption of said light, the magnetic moments of said optically pumpable substance to cause the nuclear magnetic moments of said xenon-129 and krypton-83 gases to be partially aligned by collisions of atoms of said optically pumpable substance with atoms of said xenon129 and krypton-83.

A nuclear magnetic moment alignment device comprising:

• a nuclear magnetic resonance cell;
• a gas or vapor of an optically pumpable substance that possesses a magnetic moment and is capable of being optically pumped, said optically pumpable substance being contained in said cell;
• at least one nuclear moment gas having a nuclear magnetic moment and chosen from the class consisting of isotopes of xenon and krypton, and contained in said cell;
• a substantial amount of at least one buffer gas contained in said cell;
• means for applying a steady magnetic field to said cell;
• and
• means for illuminating said cell with optical pumping light capable of partially aligning in one direction, by absorption of said light, the magnetic moments of said optically pumpable substance to cause the nuclear magnetic moments of each said nuclear moment gas to be partially aligned by collisions of atoms of said optically pumpable substance with atoms of each said nuclear moment gas.

A nuclear magnetic moment alignment device comprising:

• a nuclear magnetic resonance cell;
• a gas or vapor of an optically pumpable substance that possesses a magnetic moment and is capable of being optically pumped, said optically pumpable substance being contained in said cell;
• at least xenon-129 having a nuclear magnetic moment and contained in said cell;
• a substantial amount of at least one buffer gas contained in said cell;
• means for applying a steady magnetic field to said cell;
• and
• means for illuminating said cell with optical pumping light capable of partially aligning in one direction, by absorption of said light, the magnetic moments of said optically pumpable substance to cause the nuclear magnetic moments of said xenon-129 to be partially aligned by collisions of atoms of said optically pumpable substance with atoms of said xenon-129.

A nuclear magnetic resonance oscillator comprising:

• a nuclear magnetic resonance cell;
• a gas or vapor of an optically pumpable substance that possesses a magnetic moment and is capable of being optically pumped, said optically pumpable substance being contained in said cell;
• a substantial amount of at least one buffer gas contained in said cell;
• means for applying a steady magnetic field to said cell;
• means for illuminating said cell with optical pumping light capable of partially aligning in one direction, by absorption of said light, the magnetic moments of said optically pumpable substance to cause the nuclear magnetic moments of each said nuclear moment gas to be partially aligned by collisions of atoms of said optically pumpable substance with atoms of each said nuclear moment gas;
• means for causing the aligned nuclear magnetic moments of each said nuclear moment gas to precess about the direction of said steady magnetic field at the respective Larmor precession frequency of said gas includes means for detecting said Larmor frequency and means for applying in a direction orthogonal to the direction of said steady magnetic field an AC feedback magnetic field at the said detected Larmor precession frequency of each said nuclear moment gas, and further including means for detecting the phase of said Larmor precession frequency to control the phase of said AC feedback magnetic field to be essentially in quadrature with the respective phase of said precessing nuclear magnetic moments of said gas to cause a sustained precession of said moments of each of said gases.

A nuclear magnetic resonance detection device comprising:

• a nuclear magnetic resonance cell;
• a gas or vapor of an optically pumpable substance comprising a substance that possesses a magnetic moment and is capable of being optically pumped, said optically pumpable substance being contained in said cell;
• at least one nuclear moment gas having a nuclear magnetic moment and contained in said cell;
• a substantial amount of at least one buffer gas contained in said cell;
• means for applying a steady magnetic field to said cell;
• means for illuminating said cell with optical pumping light capable of partially aligning in one direction, by absorption of said light, the magnetic moments of said optically pumpable substance to cause the nuclear magnetic moments of each said nuclear moment gas to be partially aligned by collisions of atoms of said optically pumpable substance with atoms of each said nuclear moment gas;
• means for precessing the nuclear magnetic moments of each said nuclear moment gas about the direction of the steady magnetic field at the respective Larmor precession frequency of said gas;
• means for detecting said Larmor frequency;
• means for applying an AC carrier magnetic field to said cell;
• means for illuminating said cell with detection light of a wavelength approximately equal to a wavelength which can be absorbed by the optically pumpable substance, wherein said detection light has a directional component orthogonal to said AC carrier magnetic field;
• means for producing and detecting modulations in the intensity of said detection light at or near the frequency of at least one harmonic of said AC carrier magnetic field frequency;
• said means for detecting said Larmor precession frequency of each said nuclear moment gas comprising additional means for electrically demodulating at least one of said detected light intensity modulations to obtain a signal varying at the Larmor precession frequency of each said nuclear moment gas and with amplitudes proportional to the degree of alignment of said nuclear magnetic moments of each said gas.

A nuclear magnetic resonance detection device comprising:

• a nuclear magnetic resonance cell;
• a gas or vapor of an optically pumpable substance comprising a substance that possesses a magnetic moment and is capable of being optically pumped, said optically pumpable substance being contained in said cell;
• at least one nuclear moment gas each having a nuclear magnetic moment also contained in said cell, the nuclear magnetic moments of each said nuclear moment gas being at least partially aligned;
• means for applying a steady magnetic field to said cell;
• first means for illuminating said cell with optical pumping light capable of partially aligning in one direction by absorption of said light, the magnetic moments of said optically pumpable substance;
• means for precessing said aligned nuclear magnetic moments of each said nuclear moment gas about the direction of the steady magnetic field at the respective Larmor precession frequencies of each said gas;
• means for applying an AC carrier magnetic field to the cell;
• second means for illuminating said cell with detection light of a wavelength equal to or approximately equal to a wavelength which can be absorbed by the optically pumpable substance;
• said first and second means illuminating said cell with separate beams of light impinging from different directions;
• means for applying said detection light with a directional component orthogonal to the direction of said AC carrier magnetic field to produce modulations in the intensity of at least one harmonic, including the fundamental of the transmitted part of said detection light substantially at frequency of said AC carrier magnetic field thereof;
• means for detecting at least one of said m modulations in the intensity of the transmitted part of said detection light;
• and
• means for electrically demodulating said detected light intensity modulations to obtain a signal varying at the Larmor precession frequency of each said nuclear moment gas and with amplitude proportional to the degree of alignment of said nuclear magnetic moments of each said gas.

A nuclear magnetic resonance gyro for producing signals representative of the angular displacement of said gyro about a sensing axis comprising:

• a nuclear magnetic resonance cell;
• a gas or vapor of an optically pumpable substance that possesses a magnetic moment and is capable of being optically pumped, said optically pumpable substance being contained in said cell;
• two nuclear moment gases, each having a nuclear magnetic moment, contained in said cell, the nuclear magnetic moments of each said nuclear moment gas being at least partially aligned by collisions of atoms of each said nuclear magnetic moment gas with atoms of said optically pumpable substance to partially transfer said alignment from said substance to each said gas;
• means for applying a steady magnetic field to said cell substantially in the direction of a predetermined sensing axis, designated the z axis;
• means for illuminating said cell with optical pumping light capable of partially aligning the magnetic moments of said optically pumpable substance in said z direction by absorption of said light, said light having at least a component in the direction of said z axis;
• means for applying an AC carrier magnetic field, in the direction of said z axis, to said cell;
• means for illuminating said cell with detection light of a wavelength approximately equal to a wavelength which can be absorbed by said optically pumpable substance, said detection light having at least a component perpendicular to said z axis to produce modulations in the intensity of the transmitted part of said detection light substantially at the frequency of at least one harmonic, including the fundamental, of the frequency of said AC carrier magnetic field;
• means for precessing said aligned nuclear magnetic moments of each said nuclear moment gas about said z axis at the respective Larmor precession frequencies of each said gas, including means for applying an AC feedback magnetic field at said detected Larmor precession frequencies of each said nuclear moment gas in a direction orthogonal to said z axis and further including means for detecting the phase of said Larmor precession frequencies, said detected phase of said Larmor precession frequencies being used to control the respective phases of said AC feedback magnetic fields substantially in quadrature with the phase of said precessing nuclear magnetic moments of each said gas to cause a sustained precession of said moments of each said gas;
• means for detecting modulations in the intensity of the transmitted part of said detection light and for changing said detected modulations into electrical signals;
• means for electrically demodulating said modulation signals to obtain signals varying at the Larmor precession frequencies of each of said nuclear moment gases, and a signal varying at the difference between said Larmor precession frequencies, with amplitudes of said signals proportional to the degree of alignment of said nuclear magnetic moments of each said gas;
• means for accurately controlling the magnitude and direction of said steady state magnetic field;
• and
• means for producing signals which are a measure of angular displacement of said gyroscope about said z axis as changes in phase of the Larmor precession frequency of at least one of said nuclear moment gases.