US5122744A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gradiometer having a magnetometer which cancels background magnetic field from other magnetometers
Assignee: International Business Machines Corp
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Filing: 1990-10-09
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Granted: 1992-06-16
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Expires: 2010-10-09
Abstract
Abstract A gradiometer utilizes at least three vector magnetometers (preferably SQUIDs) to measure a magnetic field gradient. The gradiometer includes a reference magnetometer and a plurality of sensor magnetometers, wherein the reference magnetometer (SQUID) used to cancel background magnetic fields from outputs of the sensor magnetometers via a feedback loop provided with a signal from the reference magnetometer. Similarly, higher order gradiometers can be built using a reference magnetometer cube and a plurality of sensor magnetometer cubes.
Inventors
- 👤 Roger H. Koch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 23:53
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/02; G01R33/022; Y; Y10; Y10S; Y10S505/00; Y10S505/825; Y10S505/842; Y10S505/843; Y10S505/845; Y10S505/846
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
76 words
A gradiometer for measuring a magnetic field gradient, comprising: a plurality of sensor magnetometers each producing an output; a reference magnetometer rigidly mounted to said plurality of sensor magnetometers, said reference magnetometer generating a reference output for cancelling a background magnetic field from respective outputs of said sensor magnetometers to produce a plurality of cancelled sensor magnetometer outputs; and means for providing said magnetic field gradient by performing magnetic subtraction on said cancelled sensor magnetometer outputs.
Claim 2
Dependent Claim
76 words
A gradiometer for measuring a magnetic field gradient, comprising: a plurality of sensor magnetometers each producing an output; a reference magnetometer rigidly mounted to said plurality of sensor magnetometers, said reference magnetometer generating a reference output for cancelling a background magnetic field from respective outputs of said sensor magnetometers to produce a plurality of cancelled sensor magnetometer outputs; and means for providing said magnetic field gradient by performing magnetic subtraction on said cancelled sensor magnetometer outputs.
Claim 3
Dependent Claim
17 words
A gradiometer as claimed in claim 1, wherein said sensor magnetometers are Superconducting Quantum Interference Devices (SQUIDS).
Claim 4
Dependent Claim
18 words
A gradiometer as claimed in claim 1, wherein said reference magnetometer is a Superconducting Quantum Interference Device (SQUID).
Claim 5
Dependent Claim
21 words
A gradiometer as claimed in claim 1, wherein said reference magnetometer provides a feedback signal to cancel said background magnetic field.
Claim 6
Dependent Claim
23 words
A gradiometer as claimed in claim 1 wherein each of said sensor magnetometers and said reference magnetometer are Superconducting Quantum Interference Devices (SQUIDs).
Claim 7
Dependent Claim
16 words
A gradiometer as claimed in claim 5, wherein said SQUIDs include Josephson elements having weak links.
Claim 8
Dependent Claim
19 words
A gradiometer as claimed in claim 5, wherein high T c superconductive materials are used for fabricating said SQUIDs.
Claim 9
Dependent Claim
16 words
A gradiometer as claimed in claim 1, wherein a number of said sensor magnetometers is two.
Claim 10
Dependent Claim
20 words
A gradiometer as claimed in claim 1, wherein superconducting loops of each of said magnetometers are parallel to each other.
Claim 11
Dependent Claim
35 words
A gradiometer as claimed in claim 1, further comprising a feedback coil associated with each of said sensor magnetometers and said reference magnetometer wherein said feedback coils are used to cancel said background magnetic field.
Claim 12
Dependent Claim
56 words
A gradiometer as claimed in claim 1, wherein each of said sensor magnetometers and said reference magnetometer is a magnetometer cube provided with a first magnetometer, a second magnetometer and a third magnetometer on respective non-parallel sides of said magnetometer cube so as to provide a plurality of sensor magnetometer cubes and a reference magnetometer cube.
Claim 13
Dependent Claim
17 words
A gradiometer as claimed in claim 11, wherein a number of said sensor magnetometer cubes is three.
Claim 14
Dependent Claim
25 words
A gradiometer as claimed in claim 12, wherein said three sensor magnetometer cubes and said reference magnetometer cube are all situated in a common plane.
Claim 15
Dependent Claim
17 words
A gradiometer as claimed in claim 11, wherein a number of said sensor magnetometer cubes is two.
Claim 16
Dependent Claim
25 words
A gradiometer as claimed in claim 14, wherein said two difference magnetometer cubes and said average magnetometer cube are all situated in a common line.
Claim 17
Dependent Claim
22 words
A gradiometer as claimed in claim 11, wherein said gradiometer makes at least a five axis measurement of said magnetic field gradient.
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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) | 1995-06-16 | 1995-12-16 | 1996-06-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-06-16 | 1999-12-16 | 2000-06-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-06-16 | 2003-12-16 | 2004-06-16 | $7700.00 | Window Closed / Lapsed |