US4712065A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic field sensors, in particular optical fiber magnetometers
Assignee: STC PLC
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Filing: 1986-02-20
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Granted: 1987-12-08
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Expires: 2006-02-20
Abstract
Abstract In a fiber optic interferometric magnetic sensor or magnetic gradient detector a magnetic bias field is applied to a magnetically sensitized portion of an optical fiber by means which are driven by optical power whereby a completely passive sensor head arrangement may be achieved. In a magnetic gradient detector optical power from a high power laser (34) may be supplied via an optical fiber (35) to illuminate a solar cell 27 to whose electrical output terminals solenoids (25,26) are connected. A portion of a respective optical fiber (21, 22) which is magnetically sensitized, by for example bonding to a strip of magnetostrictive material (23, 24), is disposed inside each solenoid (25, 26).
Inventors
- 👤 Gillies D. Pitt
- 👤 Philip Extance
- 👤 Roger E. Jones
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 06:58
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/02; G01R33/032; G01R33/0327
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
39 words
A magnetic field sensor including a signal mode optical fiber, a portion of which is magnetically sensitised by being associated with magnetostrictive material, and means for generating a bias magnetic field at said portion, which means is optically powered.
Claim 2
Dependent Claim
39 words
A magnetic field sensor including a signal mode optical fiber, a portion of which is magnetically sensitised by being associated with magnetostrictive material, and means for generating a bias magnetic field at said portion, which means is optically powered.
Claim 3
Dependent Claim
65 words
A magnetic field sensor as claimed in claim 1, wherein said bias magnetic field generating means includes a solar cell, a respective optical fiber for supplying optical power from a high power laser source to illuminate the solar cell and a solenoid in which the magnetically sensitised optical fiber portion is located, the solenoid being connected across the electrical output terminals of the solar cell.
Claim 4
Dependent Claim
44 words
A magnetic field sensor as claimed in claim 2, wherein said bias magnetic field generating means serves to provide an a.c. bias magnetic field whose bias frequency is transmitted as the repetition rate of optical pulses transmitted down the high power laser optical fiber.
Claim 5
Dependent Claim
117 words
A magnetic field sensor as claimed in claim 1, wherein said bias magnetic field generating means includes a resonant silicon transducer comprising a thin silicon vibratable element to which is attached a permanent magnet, a magnetic circuit in which are disposed the transducer and the magnetiacally sensitised fiber portion, a high power laser source, and a respective optical fiber for supplying optical power from the high power laser source to the transducer, the optical power from the high power lasser source serving to thermally excite the vibratable element and cause it to vibrate and oscillate the permanent magnet, thus providing an a.c. magnetic field which is routed to the magnetically sensitised fiber portion via the magnetic circuit.
Claim 6
Dependent Claim
45 words
An optical fiber interfrometric magnetometer comprising a magnetic field sensor including a single mode optical fibre a portion of which is magnetically sensitised by being associated with magnetostrictive material, and means for generating a bias magnetic field at said portion, which means is optically powered.
Claim 7
Dependent Claim
45 words
An optical fiber interfrometric magnetometer comprising a magnetic field sensor including a single mode optical fibre a portion of which is magnetically sensitised by being associated with magnetostrictive material, and means for generating a bias magnetic field at said portion, which means is optically powered.
Claim 8
Dependent Claim
18 words
An optical fiber interferometric magnetometer as claimed in claim 5 and including means for passively demodulating the interferometer.
Claim 9
Dependent Claim
47 words
An optical fiber interferometric magnetic gradient detector comprising a magnetic field sensor including a single mode optical fibre, a portion of which is magnetically sensitised by being associated with magetostrictive material, and means for generating a bias magnetic field at said portion, which means is optically powered.
Claim 10
Dependent Claim
47 words
An optical fiber interferometric magnetic gradient detector comprising a magnetic field sensor including a single mode optical fibre, a portion of which is magnetically sensitised by being associated with magetostrictive material, and means for generating a bias magnetic field at said portion, which means is optically powered.
Claim 11
Dependent Claim
20 words
An optical fiber interferometric magnetic gradient detector as claimed in claim 7 and including means for passively demodulating the interferometer.
References Cited (Backward Citations)
US4600885A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-12-07 | 1991-06-08 | 1991-12-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-12-07 | 1995-06-08 | 1995-12-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-12-07 | 1999-06-08 | 1999-12-08 | $7700.00 | Window Closed / Lapsed |