US3778700A
Expired / Lapsed
US
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Optically pumped nuclear magnetic resonance gyroscope
Assignee: Kearfott Guidance and Navigation Corp
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Filing: 1971-06-07
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Granted: 1973-12-11
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Expires: 1991-06-07
Abstract
Abstract A nuclear magnetic resonance gyroscope which obtains rotational information from the phases of precessing nuclear magnetic moments for determining the angle of rotation of the gyroscope about a sensitive axis. The gyroscope comprises a pair of spin generators each having a mercury absorption cell containing 199Hg and 201Hg. The cells are arranged so that each cell is subjected to a DC H0 magnetic field and to an AC H1 magnetic field in a direction perpendicular to the H0 field. The respective H0 fields are arranged in antiparallel directions. A common pumping lamp provides a beam of randomly polarized light at 2537 A. which is plane-polarized into orthogonal beams of light by a Brewster angle polarizer. The orthogonal beams of light are reflected to intersect the absorption cells in each of the spin generators after being circularly polarized by a quarter wave plate. A common readout lamp provides a source of randomly polarized light which is split into a pair of plane-polarized readout beams which respectively intersect the absorption cells of the spin generators. The readout beam passes through the absorption cell so that its angle of polarization is oscillated by the Faraday effect at the Larmor frequency. The resultant polarization modulated readout beam is converted to an amplitude modulated beam in an analyzer which provides a periodic amplitude varying signal to a photomultiplier detector circuit. The H1 field generator is in circuit with the photomultiplier for generating the H1 field for the absorption cell in the associated spin generator. Readout and control circuit means are provided for comparing the phases of the two resonance signals produced by each absorption cell to produce an error signal for driving a motor to control the displacement of a shaft and to provide a control signal to the H0 field generator to maintain the phase relationships of the respective resonance signals. The angular rotation of the shaft will be proportional to the rotation of the gyroscope about the sensitive axis, parallel to the H0 direction, with respect to inertial space. One embodiment of the mechanical structure for housing a portion of the gyroscope is also disclosed.
Inventors
- 👤 D Bayley
- 👤 I Greenwood
- 👤 J Simpson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:53
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/02; G01R33/032; G01R33/0322
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
199 words
A nuclear magnetic resonance gyroscope which obtains rotational information from the phase of precessing nuclear magnetic moments for determining the angle of rotation of the gyroscope about a sensitive axis and oriented with respect to an arbitrary x, y, z coordinate system comprising: a first and second assorption cell containing a material for producing nuclear magnetic resonance signals from a sample in said cell, means for producing at least two unidirectional magnetic fields, the first of said magnetic fields being oriented in a positive z direction and intersecting said first absorption cell, the second unidirectional magnetic field being oriented in a negative z direction and intersecting the second absorption cell, means for subjecting each of said first and said second absorption cells to an AC magnetic field in a direction perpendicular to the unidirectional magnetic field, a common readout source of randomly polarized light, and a Brewster angle polarizer located between said readout source and said first cell for transmitting planar polarized light derived from said randomly polarized light in such a manner as to intersect said first cell and for reflecting planar polarized light derived from said randomly-polarized light in such a manner to intersect said second cell.
Claim 2
Dependent Claim
199 words
A nuclear magnetic resonance gyroscope which obtains rotational information from the phase of precessing nuclear magnetic moments for determining the angle of rotation of the gyroscope about a sensitive axis and oriented with respect to an arbitrary x, y, z coordinate system comprising: a first and second assorption cell containing a material for producing nuclear magnetic resonance signals from a sample in said cell, means for producing at least two unidirectional magnetic fields, the first of said magnetic fields being oriented in a positive z direction and intersecting said first absorption cell, the second unidirectional magnetic field being oriented in a negative z direction and intersecting the second absorption cell, means for subjecting each of said first and said second absorption cells to an AC magnetic field in a direction perpendicular to the unidirectional magnetic field, a common readout source of randomly polarized light, and a Brewster angle polarizer located between said readout source and said first cell for transmitting planar polarized light derived from said randomly polarized light in such a manner as to intersect said first cell and for reflecting planar polarized light derived from said randomly-polarized light in such a manner to intersect said second cell.
Claim 3
Dependent Claim
39 words
The gyroscope as set forth in claim 1 and further including output means for comparing the respective phases of the resonance signal produced by each absorption cell to produce a representation of the angle of rotation of the gyroscope.
Claim 4
Dependent Claim
39 words
The gyroscope as set forth in claim 2 wherein said output means includes a first detector and a second detector which respectively provide signals for controlling the AC field to each of said first and said second absorption cell.
Claim 5
Dependent Claim
40 words
The gyroscope as set forth in claim 2 wherein said output means includes first and second conversion means for respectively converting said first and second readout beams to amplitude modulated beams to produce first and second periodic amplitude varying signals.
Claim 6
Dependent Claim
44 words
The gyroscope as set forth in claim 4 wherein said output means includes a first and second linear analyzer respectively arranged to intercept each of said first and second readout beams after passage through said absorption cells and before detection in said output means.
Claim 7
Dependent Claim
61 words
The gyroscope as set forth in claim 2 further including an output indicator, a shaft in cooperation with said output indicator to provide an indication of the angle of rotation of said shaft, and a motor for rotating said shaft at an angle proportional to the difference between the phases of the signals from said first cell and said second cell.
Claim 8
Dependent Claim
68 words
The gyroscope as set forth in claim 2 wherein each of said first cell and said second cell includes material which produces a pair of nuclear magnetic resonance signals from each sample, the frequency of said signals being separable and arranged so that the plane of polarization of each of said readout beams is oscillated by the Faraday effect at the Larmor frequencies of each of said cells.
Claim 9
Dependent Claim
35 words
The gyroscope as set forth in claim 7 wherein said output means compares the phases of the respective signals to produce a signal which controls the DC magnetic field of one of said spin generators.
Claim 10
Dependent Claim
60 words
The gyroscope as set forth in claim 8 whereiN said first cell is in circuit with a source of oscillation approximately equal to the frequency of one of the signals produced by said first cell and means for comparing the phase of said source of reference frequency with the phase of one of the signals produced by said first cell.
Claim 11
Dependent Claim
32 words
The gyroscope as set forth in claim 1 further including means for housing said absorption cell, said housing means including magnetic shielding means for magnetically shielding said first and second absorption cells.
Claim 12
Dependent Claim
74 words
The gyroscope as set forth in claim 10 wherein said housing means further includes a pair of H0 coils for generating a DC magnetic field, means for receiving said pair of H0 coils so that each has its axis aligned with an H0 field axis, said H0 field axis intersecting an absorption cell located within said housing, and an H0 coil support member for retaining said H0 coil receiving means in a secured relationship.
Claim 13
Dependent Claim
74 words
The gyroscope as set forth in claim 11 wherein said housing means further includes a pair of H1 coils for generating an AC magnetic field, means for receiving said pair of H1 coils so that each has its axis aligned with an H1 field axis, said H1 field axis intersecting an absorption cell located within said housing, and an H1 coil support member for retaining said H1 coil receiving means in a secured relationship.
Claim 14
Dependent Claim
23 words
The apparatus as set forth in claim 1 further including pumping means for optically pumping each of said first and said second cells.
Claim 15
Dependent Claim
74 words
The gyroscope as set forth in claim 13 wherein said pumping means includes: a common pumping source of randomly polarized light, and means for transmitting a first planar polarized beam of light derived from said common pumping source of light in such a manner to intersect said first cell and reflecting a second planar polarized beam of light derived from said common source of light in such a manner to intersect said second cell.
Claim 16
Dependent Claim
50 words
The gyroscope as set forth in claim 14 wherein said pumping means further includes means for reflecting each of said first and said second planar polarized beams of light in such a manner that said beams respectively intersect said first cell and said second cell in a positive z direction.
Claim 17
Dependent Claim
23 words
The gyroscope as set forth in claim 15 further including means for circularly polarizing each of said first and said second pumping beams.
Claim 18
Dependent Claim
40 words
The gyroscope as set forth in claim 16 wherein said optical pumping means further includes a first quarter wave plate and a second quarter wave plate for respectively circularly polarizing light in said first plane and in said second plane.
Claim 19
Dependent Claim
54 words
The gyroscope as set forth in claim 17 wherein said optical pumping means further includes a first reflector and a second reflector disposed so that said first reflector reflects light in said first plane to intersect said first cell and said second reflector reflects light in said second plane to intersect said second cell.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-10 | 1977-06-11 | 1977-12-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-10 | 1981-06-11 | 1981-12-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-10 | 1985-06-11 | 1985-12-11 | $7700.00 | Window Closed / Lapsed |