US4842403A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sensing strain and temperature
Assignee: Prysmian Cables and Systems Ltd
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Filing: 1988-12-05
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Granted: 1989-06-27
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Expires: 2008-12-05
Abstract
Abstract An optical fibre sensor 11 has two monomode cores 13,14 arranged in a common cladding 15 to allow cross-talk of optical signals between the cores as a function of strain, temperature and optical wavelength. Optical signals are generated by a generator 16 at two wavelengths, at one of which cross-talk between the cores 13,14 is temperature independent. The generated optical signals are injected into the element 11 via an optical fibre lead 18 having a single monomode core 19 which is connected to one of the cores 13 of the element 11 at one end thereof and after cross-talk between the cores, optical signals are extracted from the element, for example via the same lead 18, and processed to determine temperature and strain at the element.
Inventors
- 👤 Eleanor J. Tarbox
- 👤 Paul L. Scrivener
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 09:28
CPC Classifications
G; G01; G01L; G01L1/00; G01L1/24; G01L1/242; G01B; G01B11/00; G01B11/16; G01B11/18; G01K; G01K11/00; G01K11/32
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
151 words
A strain and temperature sensing apparatus including: an optical fiber sensor element having at least two monomode cores arranged in a common cladding to allow cross-talk of optical signals between said cores as a function of strain, temperature and optical wavelength; means for generating two optical signals at two different wavelengths, the cross-talk between said cores at one of said wavelengths being temperature independent and the cross-talk between said cores at the other of said wavelengths being both temperature and strain dependent, and each signal being substantially of a single wavelength; means for combining said generated optical signals and injecting both said signals into said element; means for extracting optical signals from said element; and processing means for comparing the optical signals which are temperature independent with the signals which are temperature and strain dependent and thereby separately determining both the temperature and strain at the element from said extracted signals.
Claim 2
Dependent Claim
151 words
A strain and temperature sensing apparatus including: an optical fiber sensor element having at least two monomode cores arranged in a common cladding to allow cross-talk of optical signals between said cores as a function of strain, temperature and optical wavelength; means for generating two optical signals at two different wavelengths, the cross-talk between said cores at one of said wavelengths being temperature independent and the cross-talk between said cores at the other of said wavelengths being both temperature and strain dependent, and each signal being substantially of a single wavelength; means for combining said generated optical signals and injecting both said signals into said element; means for extracting optical signals from said element; and processing means for comparing the optical signals which are temperature independent with the signals which are temperature and strain dependent and thereby separately determining both the temperature and strain at the element from said extracted signals.
Claim 3
Dependent Claim
69 words
Apparatus as claimed in claim 1, wherein said means for combining and injecting said generated optical signals into said element and for extracting optical signals therefrom comprises an optical fiber having a single monomode core which is connected at one end to said means for generating two optical signals and connected at its opposite end to one of said cores of said element at one end of the latter.
Claim 4
Dependent Claim
48 words
Apparatus as claimed in claim 2, comprising a further said optical fiber sensor element serially connected to said first-mentioned element by a further said optical fiber having a core connecting the said one core of the first-mentioned element to one of the said cores of said further element.
Claim 5
Dependent Claim
58 words
Apparatus as claimed in claim 2, comprising a plurality of further said optical fiber sensor elements serially connected to said first-mentioned element by respective further said optical fibers, the cores of said further said optical fibers connecting the said one core of the first-mentioned said element to one of the said cores in each of said further elements.
Claim 6
Dependent Claim
13 words
Apparatus as claimed in claim 1, wherein said generating means is pulse modulated.
Claim 7
Dependent Claim
44 words
Apparatus as claimed in claim 1, wherein said generating means comprises two laser sources, one of said sources generating signals at one of said wavelengths at substantially the same time that the other of said sources generates signals at the other of said wavelengths.
Claim 8
Dependent Claim
49 words
Apparatus as claimed in claim 1, comprising reflecting means provided at the end of said sensor element opposite to the end thereof connected to said optical fiber having a single monomode core for reflecting optical signals back through said one core thereof into said core of said optical fiber.
Claim 9
Dependent Claim
28 words
Apparatus as claimed in claim 7, wherein said generating means is selected from the group consisting of two laser sources, two L.E.D.'s and two filtered white light sources.
Claim 10
Dependent Claim
19 words
Apparatus as claimed in claim 7, wherein said generating means comprises means for modulating the optical signals generated thereby.
Claim 11
Dependent Claim
84 words
Apparatus as claimed in claim 1, wherein said means for combining and injecting said generated optical signals into said element and said means for extracting optical signals therefrom comprises two optical fibers each having a single monomode core, one of said fibers being connected between said generating means and one end of the element for injecting said generated optical signals into said element, and the other of said fibers being connected to the other end of said element for extracting said optical signals therefrom.
Claim 12
Dependent Claim
54 words
Apparatus as claimed in claim 10, wherein one of the said cores of said element is connected at said one end thereof to the said core of said one of said one of said optical fibers and is connected at said other end thereof to said core of said other of said optical fibers.
Claim 13
Dependent Claim
37 words
Apparatus as claimed in claim 1, wherein said generating means comprises a source of polarized light, and said means for combining and injecting said signals and said means for extracting optical signals are polarization maintaining optical fibers.
Claim 14
Independent Claim
139 words
A method of sensing strain and temperature comprising at least substantially simultaneously injecting two optical signals at two different wavelengths into an optical fiber sensor element having at least two monomode cores arranged in a common cladding to allow cross-talk of said optical signals between the cores as a function of strain, temperature and optical wavelength, each of said signals being substantially of a single wavelength and one of said wavelengths being such that cross-talk between the cores is temperature independent and the other of said wavelengths being such that cross-talk between said cores is both temperature and strain dependent; extracting optical signals from the element; and processing the extracted signals by comparing the signals which are temperature independent with the signals which are temperature and strain dependent to determine separately both the temperature and strain at said element.
Claim 15
Independent Claim
139 words
A method of sensing strain and temperature comprising at least substantially simultaneously injecting two optical signals at two different wavelengths into an optical fiber sensor element having at least two monomode cores arranged in a common cladding to allow cross-talk of said optical signals between the cores as a function of strain, temperature and optical wavelength, each of said signals being substantially of a single wavelength and one of said wavelengths being such that cross-talk between the cores is temperature independent and the other of said wavelengths being such that cross-talk between said cores is both temperature and strain dependent; extracting optical signals from the element; and processing the extracted signals by comparing the signals which are temperature independent with the signals which are temperature and strain dependent to determine separately both the temperature and strain at said element.
References Cited (Backward Citations)
US4151747A
Cited
US4295738A
Cited
US4295739A
Cited
US4298794A
Cited
US4420251A
Cited
WO1986001286A1
Cited
US4653906A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-06-26 | 1992-12-26 | 1993-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-06-26 | 1996-12-26 | 1997-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-06-26 | 2000-12-26 | 2001-06-27 | $7700.00 | Window Closed / Lapsed |