US3703682A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Long axis gradiometer
Assignee: United States Department of the Navy
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Filing: 1968-10-30
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Granted: 1972-11-21
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Expires: 1988-10-30
Abstract
Abstract A gradiometer has two magnetometers axially spaced apart by an internally non-reflecting tube. One magnetometer is attached to a light source fixed centrally of a photo multiplier array at one end of the tube. The source transmits collimated or cophasal light to the other end of the tube where it is reflected by a mirror mounted on a two axis gimbal. The other magnetometer is attached to the gimbal. The reflected light returns to the source if the magnetometers are coaxial when the magnetometer axes are not parallel, the reflected light is sensed by the photomultiplier array the outputs of which drive a servo to realign the gimbaled mirror/magnetometer arrangement to parallelism so that sensed earth''s field components are eliminated during operational use of the magnetometers as a gradiometer.
Inventors
- 👤 Miles X Wickman
- 👤 Harold P Cohn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:58
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/02; G01R33/022
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
182 words
In a gradiometer, apparatus for aligning the two axially spaced apart first and second magnetometers thereof so that their axes are essentially exactly parallel whereby the effects of earth''s magnetic field on both magnetometers are the same comprising: means mounting the first and second magnetometers substantially coaxially and spaced apart; light source means supported coaxially with the first magnetometer for transmitting a beam of light; reflecting means supported with the second magnetometer for reflecting the transmitted beam; servo motor means for moving said magnetometers relatively to each other responsive to error signals; light responsive means located in fixed relation to said light source for producing, in response to impingement of the beam of light reflected thereon, error signals indicative of displacement of the reflected beam from the transmitted beam, and thus error signals indicative of the existence of and extent of non-parallelism of the axes of the magnetometers; and means for feeding the error signals to said servo motor means whereby the servo motor means moves said reflecting means to bring both light beams into coincidence thereby parallelly aligning the magnetometer axes.
Claim 2
Dependent Claim
182 words
In a gradiometer, apparatus for aligning the two axially spaced apart first and second magnetometers thereof so that their axes are essentially exactly parallel whereby the effects of earth''s magnetic field on both magnetometers are the same comprising: means mounting the first and second magnetometers substantially coaxially and spaced apart; light source means supported coaxially with the first magnetometer for transmitting a beam of light; reflecting means supported with the second magnetometer for reflecting the transmitted beam; servo motor means for moving said magnetometers relatively to each other responsive to error signals; light responsive means located in fixed relation to said light source for producing, in response to impingement of the beam of light reflected thereon, error signals indicative of displacement of the reflected beam from the transmitted beam, and thus error signals indicative of the existence of and extent of non-parallelism of the axes of the magnetometers; and means for feeding the error signals to said servo motor means whereby the servo motor means moves said reflecting means to bring both light beams into coincidence thereby parallelly aligning the magnetometer axes.
Claim 3
Dependent Claim
182 words
In a gradiometer, apparatus for aligning the two axially spaced apart first and second magnetometers thereof so that their axes are essentially exactly parallel whereby the effects of earth''s magnetic field on both magnetometers are the same comprising: means mounting the first and second magnetometers substantially coaxially and spaced apart; light source means supported coaxially with the first magnetometer for transmitting a beam of light; reflecting means supported with the second magnetometer for reflecting the transmitted beam; servo motor means for moving said magnetometers relatively to each other responsive to error signals; light responsive means located in fixed relation to said light source for producing, in response to impingement of the beam of light reflected thereon, error signals indicative of displacement of the reflected beam from the transmitted beam, and thus error signals indicative of the existence of and extent of non-parallelism of the axes of the magnetometers; and means for feeding the error signals to said servo motor means whereby the servo motor means moves said reflecting means to bring both light beams into coincidence thereby parallelly aligning the magnetometer axes.
Claim 4
Dependent Claim
182 words
In a gradiometer, apparatus for aligning the two axially spaced apart first and second magnetometers thereof so that their axes are essentially exactly parallel whereby the effects of earth''s magnetic field on both magnetometers are the same comprising: means mounting the first and second magnetometers substantially coaxially and spaced apart; light source means supported coaxially with the first magnetometer for transmitting a beam of light; reflecting means supported with the second magnetometer for reflecting the transmitted beam; servo motor means for moving said magnetometers relatively to each other responsive to error signals; light responsive means located in fixed relation to said light source for producing, in response to impingement of the beam of light reflected thereon, error signals indicative of displacement of the reflected beam from the transmitted beam, and thus error signals indicative of the existence of and extent of non-parallelism of the axes of the magnetometers; and means for feeding the error signals to said servo motor means whereby the servo motor means moves said reflecting means to bring both light beams into coincidence thereby parallelly aligning the magnetometer axes.
Claim 5
Dependent Claim
28 words
Apparatus according to claim 1 wherein said means mounting the first and second magnetometers comprises a tube free of internal reflection enclosing the transmitted and reflected light beams.
Claim 6
Dependent Claim
49 words
Apparatus in accordance with claim 2 wherein said servo motor means is mounted at one end of the tube for driving the second magnetometer and reflecting means in unison therewith about two perpendicular axes, the first magnetometer being affixed to the other end of the tube for movement therewith.
Claim 7
Dependent Claim
14 words
Apparatus in accordance with claims 2 or 3 in which the tube is watertight.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-11-21 | 1976-05-22 | 1976-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-21 | 1980-05-22 | 1980-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-21 | 1984-05-22 | 1984-11-21 | $7700.00 | Window Closed / Lapsed |