US4725143A
Expired / Lapsed
US
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Interferometric sensor
Assignee: KENT SCIENTIFIC AND INDUSTRIAL PROJECTS Ltd PHYSICS LABORATORY UNIVERSITY A BRITISH Co
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Filing: 1985-06-28
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Granted: 1988-02-16
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Expires: 2005-06-28
Abstract
Abstract An interferometric sensor includes an optical fiber polarimetric sensing element (5) for detecting a required measurand and is configured so as to derive interference output signals, which are simultaneously monitored by photodetectors (9, 11), from both conventional, for example, Michelson, and polarimetric interferometer arrangements. The sensor therefore offers the high resolution of a conventional interferometer in conjunction with the increased dynamic range of a polarimetric device.
Inventors
- 👤 Julian D. C. Jones
- 👤 David A. Jackson
- 👤 Michael Corke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 01:49
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/344; G01K; G01K11/00; G01K11/32
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
129 words
An interferometric sensor comprising, in combination: a sensing element adapted to detect a required measurand and comprising a polarimetric interferometer device, means for illuminating said polarimetric device with an input beam of polarised light, whereby to cause two light beams to propagate in said polarimetric device and produce two output beams therefrom, means for deriving a reference beam of light from said input beam, means for mixing said two output beams from said polarimetric device and one of said output beams and said reference beam, respectively, to produce two interference signals corresponding respectively to the phase differences between said two output beams and said one output beam and said reference beam, respectively, and means for monitoring and processing said two interference signals to produce a measurement of said measurand.
Claim 2
Dependent Claim
129 words
An interferometric sensor comprising, in combination: a sensing element adapted to detect a required measurand and comprising a polarimetric interferometer device, means for illuminating said polarimetric device with an input beam of polarised light, whereby to cause two light beams to propagate in said polarimetric device and produce two output beams therefrom, means for deriving a reference beam of light from said input beam, means for mixing said two output beams from said polarimetric device and one of said output beams and said reference beam, respectively, to produce two interference signals corresponding respectively to the phase differences between said two output beams and said one output beam and said reference beam, respectively, and means for monitoring and processing said two interference signals to produce a measurement of said measurand.
Claim 3
Dependent Claim
71 words
The interferometric sensor claimed in claim 1, wherein said mixing means comprises beam splitting means for splitting said output beams emanating from said polarimetric device into fractions which propagate along first and second optical paths, means for mixing said fraction of said one output beam propagating along said first optical path with said reference beam, and means for intermixing said fractions of said output beams propagating along said second optical path.
Claim 4
Dependent Claim
57 words
The interferometric sensor claimed in claim 2, wherein said means for mixing said fraction of said one output beam and said reference beam includes first polarising means located along said first optical path and oriented to transmit only said fraction of said one output beam propagating along said first optical path for mixing with said reference beam.
Claim 5
Dependent Claim
26 words
The interferometric sensor claimed in claim 3, wherein said reference beam is derived by reflection of a fraction of said input beam illuminating said polarimetric device.
Claim 6
Dependent Claim
29 words
The interferometric sensor claimed in claim 4, including second polarising means located along said second optical path and oriented to transmit only said fractions of both said output beams.
Claim 7
Dependent Claim
35 words
The interferometric sensor claimed in claim 2, wherein said monitoring means comprises photodetector means located along said first and second optical paths for sensing said two interference signals and producing electrical output signals corresponding thereto.
Claim 8
Dependent Claim
17 words
The interferometric sensor claimed in claim 1, wherein said polarimetric device is an optical fibre sensing element.
Claim 9
Dependent Claim
37 words
The interferometric sensor claimed in claim 7, wherein said optical fibre sensing element comprises a birefringent optical fibre having substantially orthogonal eigen modes oriented so that both modes are excited by said polarised input beam of light.
Claim 10
Dependent Claim
83 words
The interferometric sensor claimed in claim 7, wherein said optical fibre sensing element has an optical input and an optical output at one end thereof, said illuminating means being arranged to launch said input beam into said one end of said optical fibre sensing element, and said optical fibre sensing element having reflective means at an opposite end, whereby return light beams are propagated in said optical fibre sensing element for producing said two output beams which emanate from said one end thereof.
Claim 11
Dependent Claim
94 words
The interferometric sensor claimed in claim 9, wherein said mixing means comprises beam splitting means for splitting said output beams emanating from said one end of said optical fibre sensing element into fractions which propagate along first and second optical paths, means for mixing said fraction of said one beam directed along said first optical path with said reference beam to produce a first one of said interference signals, and means for intermixing said fractions of said output beams propagating along said second optical path to produce a second one of said interference signal.
Claim 12
Dependent Claim
40 words
The interferometric sensor claimed in claim 10, wherein said mixing means includes polarising means located respectively along said first and second optical paths and oriented respectively to permit only transmission of the required light beams for producing said interference signals.
Claim 13
Dependent Claim
22 words
The interferometric sensor claimed in claim 11, wherein said reference beam is derived by reflection of a fraction of said input beam.
Claim 14
Dependent Claim
27 words
The interferometric sensor claimed in claim 12, wherein said beam splitting means is adapted also to reflect said fraction of said input beam forming said reference beam.
Claim 15
Dependent Claim
47 words
The interferometric sensor claimed in claim 13, wherein said monitoring means comprising photodetector means located along said first and second optical paths downstream of said polarising means and responsive to said light beams incident thereon to produce electrical output signals corresponding respectively to said two interference signals.
References Cited (Backward Citations)
GB2057681A
Cited
EP0038950A2
Cited
DE3031961A1
Cited
US4442350A
Cited
GB2117132A
Cited
EP0104932A2
Cited
GB2144215A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-02-15 | 1991-08-17 | 1992-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-15 | 1995-08-17 | 1996-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-15 | 1999-08-17 | 2000-02-16 | $7700.00 | Window Closed / Lapsed |