CA1290589C - Sensing strain and temperature - Google Patents
Sensing strain and temperatureInfo
- Publication number
- CA1290589C CA1290589C CA000539916A CA539916A CA1290589C CA 1290589 C CA1290589 C CA 1290589C CA 000539916 A CA000539916 A CA 000539916A CA 539916 A CA539916 A CA 539916A CA 1290589 C CA1290589 C CA 1290589C
- Authority
- CA
- Canada
- Prior art keywords
- optical
- cores
- optical signals
- temperature
- core
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000003287 optical effect Effects 0.000 claims abstract description 67
- 239000013307 optical fiber Substances 0.000 claims abstract description 27
- 238000005253 cladding Methods 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims description 2
- 230000010287 polarization Effects 0.000 claims description 2
- 239000000835 fiber Substances 0.000 description 6
- 238000010276 construction Methods 0.000 description 3
- 230000003455 independent Effects 0.000 description 3
- 229910052729 chemical element Inorganic materials 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 230000009977 dual effect Effects 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 230000002706 hydrostatic effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- KRTSDMXIXPKRQR-AATRIKPKSA-N monocrotophos Chemical compound CNC(=O)\C=C(/C)OP(=O)(OC)OC KRTSDMXIXPKRQR-AATRIKPKSA-N 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 230000001902 propagating effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L1/00—Measuring force or stress, in general
- G01L1/24—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet
- G01L1/242—Measuring force or stress, in general by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis using infrared, visible light, ultraviolet the material being an optical fibre
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
- G01B11/18—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge using photoelastic elements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K11/00—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00
- G01K11/32—Measuring temperature based upon physical or chemical changes not covered by groups G01K3/00, G01K5/00, G01K7/00 or G01K9/00 using changes in transmittance, scattering or luminescence in optical fibres
Abstract
ABSTRACT
SENSING STRAIN AND TEMPERATURE
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.
SENSING STRAIN AND TEMPERATURE
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.
Description
~9~139 SE~SING S~RAIX AND TEMPERATURE
This invention relates to sensing strain and temperature.
It is known that when an optical fibre comprises two cores arranged in common cladding 'cross-talk' between the cores may occur by the light energy propagating in one core being transferred to the other core. Further it is known that the amount of cross-talk between the cores is a function of strain, temperature and wavelength,al-though by selection of materials, spacing and shape of lQ the cores and cladding the cross-talk may be made inde-pendent of strain or temperature. For example US Patent Specification No. 4 295738 discloses how the cross-talk may be made independent of temperature such that by in-jecting light into one core and measuring the relative intensity of light emerging from the cores the strain over the length of a dual core fibre may be determined.
An object of the present invention is to utilise the above cross-talk phenomenon in order to sense both temperature and strain.
The invention includes a method of sensing ~train and temperature comprising injecting optical slgnals~at two wavelengths into an optical fibre sensor element having at least two monomode cores arranged in a common cladding to allow cross-talk of said optical signals be-tween the cores as a function of strain, temperature and ~k 1~90~89 optical wavelength, one of said wavelengths being 6uch that cross-talk between the cores i6 temperature independ-ent, extracting optical signals from the element and processing the extracted signals to determine the temper-ature and strain of the element.
~ he invention also includes a strain and temperature sensing apparatus including an optica~ fibre sensor ele-ment having at least two monomode cores arranged in a common cladding to alloh cross-talk of optical signals between the cores as a function of strain, temperature and optical wavelengt~, and means for generatin~ optical sig-nals at two wavelengths, at one of which cross-talk between the cores is temperature independent, means for in~ecting said generated optical signals into said element and for extracting optical signals therefrom, and processing means for determining the temperature and strain at the element from said extracted optical signals.
In two embodiments of the invention described hereinafter, said means for injecting said generated optic-al signals into said element and for extracting opticalsignals therefrom comprises an optical fibre having a single monomode core which is connected to one of the cores of the element at one end thereof.
In one of these embodiments, a further said optical fibre sensor element is serially connected to 6aid first-mentioned element by a further said optical fibre, the core of which connects the said one core of the first-mentioned element to one of the cores of said further element. However, it is to be understood that this em-bodiment may be modified to comprise a plurality of furthersaid optical fibre sensor elements serially connected to 6aid first-mentioned element by respective further said optical fibres, the cores of which connect the said cne core of the fir6t-mentioned element to one of the cores in each of 6aid further elements.
1~90~
1 Preferably, in this embodiment said generating means, which may comprise two laser sources, are arranged to generate optical pulses. This enables the extracted signals to be identified by time with particular sensor elements.
In the second of the above-mentioned embodiments, reflecting means are provided at the other end of said sensor element for reflecting optical signals back through said one core thereof into the core of said optical fibre.
In a third embodiment of the invention, said means for injecting said generated optical signals into said element and for extracting optical signals therefrom comprises two optical fibres each having a single monomode core, one of said fibres being connected to one end of the element for injecting said generated optical signals into said element, and the other of said fibres being connected to the other end of the element for extracting optical signals therefrom.
Preferably in this embodiment one of the cores of said element is connected to the cores of both optical fibres.
In the second and third embodiments, said generating means may comprise two laser sources, L.E.D's or filtered white light sources and may additionally comprise means for modulating the optical signals generated thereby.
In order that the invention may be well understood, the above-mentioned three embodiments thereof, which are given by way of example only, will now be described in more detail with reference to the accompanying drawings in which:
Figure 1 shows an embodiment of the invention with two sensor elements;
Figure 2 shows an embodiment with a single sensor element;
and Figure 3 shows a "double ended" embodiment.
In Figure 1, there is shown a strain and temperature sensing apparatus 10 which comprises two optical fibre sensor elements 11 and 12. Each sensor element comprises two monomode cores 13 and 14 arranged in a common cladding 90~B9 15 to allow cross-talk of optical signals between the cores as a function of strain, temperature and optica]
wave~ength.
A device 16 for generating optical signals at two wavelengths and including two laser sources is arranged to generate optical pulses which are fed ~ia a fibre coup-ler or beam splitter 17 to an optical fibre lead 18 hav-ing a single monomode core 19 which is connected to one of the cores (shown as ~3) of the element 11 at one end thereof. The element 12 is serially connected to the element 11 by a further optical fibre lead 20 having a single monomode core 2] which connects the core 13 of the element 11 to one of the cores (shown as 13) of the ele-ment ~2. When the optical signals generated by the gen-erating device 16 are injected into the core 13 of theelement 11 via the lead 18, cross-talk between the cores 13 and 14 of the element 11 will occur and a back scattered signal will be extracted from the core 13 by the lead 18.
This back scattered signal is directed by the fibre coup-ler or beam splitter ]7 to a detector 22 and a processor23. The back scattered signal detected and processed is dependent upon the amount of cross-talk between the cores 13 and 14 o~ the element 11. At one of the two wave-lengths of the optical signals, cross-talk between the cores is temperature independent. Accordingly, the ex-tracted signals at the two wavelengths can be used to determine temperature and strain at the element 11 by the processor 23.
As will be appreciated, the optical signals iniected into the element 11 after passing through that element are transmitted via the lead 20 to the element 12 where cross-talk will occur between the cores 13 and 14 and a back scattered signal will be directed to the detector 22 and processor 23 as before. As will be appreciated the 1~90 - s-detected signals are identifiable with the particular sensor element 11 or 12 from which they are extracted by the transit time of the pulsed signals.
Whilst the apparatus in Figure 1 is illustrated as S comprising only two sensor element&, it will be appreciated that, further sensor elements of like construction can be serially connected with the illustrated elements 1] and 12 via respective optical fibre leads, the single monomode cores of which preferably connect tl~e core 13 of the element 12 (and thus the core 13 of element 11) to one of the ~ores in each of the further sensor el~ments.
The strain and temperature sensing apparatus 30 illustrated in Figure 2 comprises a single sensor element 31 of like construction to the elements 11 and 12 of apparatus 10. Like the element 11 in apparatus 10, the element 31 is connected via an optical fibre lead 32 having a single monomode core 33 and a fibre coupler or beam splitter 34 to a generating devi~e 35 which generates optic-al signals at two wavelengths, at one of which cross-talk between the cores of the element 31 is temperature inde-pendent.
In the apparatus 30, the end of the sensor element opposite the end thereof connected to the lead 32 is pro-vided with reflecting means~for reflecting optical signals back through the core of the element connected to the single core of the lead 32 and thence via the fibre coupler or beam splitter 34 to a detector 36 and processor 37. The reflecting means may be a mirror chemically grown onto the end face of the element or a mirror surface butted to that end face.
As will be appreciated the optical signal which is extracted from the sensor element by reflection is depen-dent upon the amount of cross-talk which occurs between the cores of the element 31. Accordingly, as in the appa-3~ ratus 10, the processor 37 i6 able to determine the ~905~3 temperature and strain st the element 31 from th~ extrac-ted optical signals.
~ o i~prove the si~nal to noi~e ratio of the appa-ratus, the generating de~ice35 comprises means for modu-lating the optical signals generated thereby and theproce~sor 37 includes a lock-in amplifier or a tuned amp-~ifier.
In this apparatus the generatingdevice 35 may comp-rise two laser sources or alternatively two L.E.D's or two filtered white light sources.
Ihe above two apparatus may be described as being 'single-ended', since the injected and extracted optical signals travel along the same optical fibre leads.
ln Figure 3, there is illustrated an example of a strain and temperature sensing apparatus (designated 40) which may be described as 'double-ended' since it comprises an optical fibre sensor element 4] (whose construction is the same as elements 11 and 12) having respective optical fibre leads 42 and 43 connected to the two ends thereof.
Each of the optical fibre leads 42 and 43 has a single monomode cvre 44 and 45 which are connected to one of the cores of the sensor element 41. As illustrated, a generating means 46 constructed as the generating device 35 of apparatus 30 generates optical signals at two wave-lengths, at one of which cross-talk between the cores of the element 41 is temperature independent, and these opti-cal signals are injected into the element 4] via the lead 42. Lead 43 extracts optical signals from the element 41 and the extracted signals are passed to a detector 47 and processor 48 which determines the temperature and strain at the element 41.
It is to be under6tood that whilst the illustrated sensor elements comprise two cores the~e elements could comprise more than two cores in a common cladding.
It will also be appreciated that in the apparatus ~ 1~9{)S~3 disclosed, optical signals are extracted from the core of the element into which the signals are injected and it is not necessary to extract signals from the other core of the element. This is advantageous in that it allows J
5 conventional single core optical fibre leads to be used for injecting and extracting optical signals.
Advantageously, in order to assist connection between the cores of the optical fibre leads and the sensor elements, one core of the sensor element is posi-10 tioned on the longitudinal axis of the element.
It is to be understood that the strain measured with the sensing apparatus may arise from longitudinal, transverse or radial stresses (or any combination thereof) in the element. In this connection it will be appreciated 15 that radial stresses arise for example when the element is subjected to hydrostatic pressure.
We have also discovered that the sensitivity of the apparatus can be enhanced by using a polarized light source (or sources) the optical fibres, particularly for the leads 18,20;32;42,43, being chosen for their polariza-tion maintaining characteristics. Polarized light may be used in each of the above described embodiments.
This invention relates to sensing strain and temperature.
It is known that when an optical fibre comprises two cores arranged in common cladding 'cross-talk' between the cores may occur by the light energy propagating in one core being transferred to the other core. Further it is known that the amount of cross-talk between the cores is a function of strain, temperature and wavelength,al-though by selection of materials, spacing and shape of lQ the cores and cladding the cross-talk may be made inde-pendent of strain or temperature. For example US Patent Specification No. 4 295738 discloses how the cross-talk may be made independent of temperature such that by in-jecting light into one core and measuring the relative intensity of light emerging from the cores the strain over the length of a dual core fibre may be determined.
An object of the present invention is to utilise the above cross-talk phenomenon in order to sense both temperature and strain.
The invention includes a method of sensing ~train and temperature comprising injecting optical slgnals~at two wavelengths into an optical fibre sensor element having at least two monomode cores arranged in a common cladding to allow cross-talk of said optical signals be-tween the cores as a function of strain, temperature and ~k 1~90~89 optical wavelength, one of said wavelengths being 6uch that cross-talk between the cores i6 temperature independ-ent, extracting optical signals from the element and processing the extracted signals to determine the temper-ature and strain of the element.
~ he invention also includes a strain and temperature sensing apparatus including an optica~ fibre sensor ele-ment having at least two monomode cores arranged in a common cladding to alloh cross-talk of optical signals between the cores as a function of strain, temperature and optical wavelengt~, and means for generatin~ optical sig-nals at two wavelengths, at one of which cross-talk between the cores is temperature independent, means for in~ecting said generated optical signals into said element and for extracting optical signals therefrom, and processing means for determining the temperature and strain at the element from said extracted optical signals.
In two embodiments of the invention described hereinafter, said means for injecting said generated optic-al signals into said element and for extracting opticalsignals therefrom comprises an optical fibre having a single monomode core which is connected to one of the cores of the element at one end thereof.
In one of these embodiments, a further said optical fibre sensor element is serially connected to 6aid first-mentioned element by a further said optical fibre, the core of which connects the said one core of the first-mentioned element to one of the cores of said further element. However, it is to be understood that this em-bodiment may be modified to comprise a plurality of furthersaid optical fibre sensor elements serially connected to 6aid first-mentioned element by respective further said optical fibres, the cores of which connect the said cne core of the fir6t-mentioned element to one of the cores in each of 6aid further elements.
1~90~
1 Preferably, in this embodiment said generating means, which may comprise two laser sources, are arranged to generate optical pulses. This enables the extracted signals to be identified by time with particular sensor elements.
In the second of the above-mentioned embodiments, reflecting means are provided at the other end of said sensor element for reflecting optical signals back through said one core thereof into the core of said optical fibre.
In a third embodiment of the invention, said means for injecting said generated optical signals into said element and for extracting optical signals therefrom comprises two optical fibres each having a single monomode core, one of said fibres being connected to one end of the element for injecting said generated optical signals into said element, and the other of said fibres being connected to the other end of the element for extracting optical signals therefrom.
Preferably in this embodiment one of the cores of said element is connected to the cores of both optical fibres.
In the second and third embodiments, said generating means may comprise two laser sources, L.E.D's or filtered white light sources and may additionally comprise means for modulating the optical signals generated thereby.
In order that the invention may be well understood, the above-mentioned three embodiments thereof, which are given by way of example only, will now be described in more detail with reference to the accompanying drawings in which:
Figure 1 shows an embodiment of the invention with two sensor elements;
Figure 2 shows an embodiment with a single sensor element;
and Figure 3 shows a "double ended" embodiment.
In Figure 1, there is shown a strain and temperature sensing apparatus 10 which comprises two optical fibre sensor elements 11 and 12. Each sensor element comprises two monomode cores 13 and 14 arranged in a common cladding 90~B9 15 to allow cross-talk of optical signals between the cores as a function of strain, temperature and optica]
wave~ength.
A device 16 for generating optical signals at two wavelengths and including two laser sources is arranged to generate optical pulses which are fed ~ia a fibre coup-ler or beam splitter 17 to an optical fibre lead 18 hav-ing a single monomode core 19 which is connected to one of the cores (shown as ~3) of the element 11 at one end thereof. The element 12 is serially connected to the element 11 by a further optical fibre lead 20 having a single monomode core 2] which connects the core 13 of the element 11 to one of the cores (shown as 13) of the ele-ment ~2. When the optical signals generated by the gen-erating device 16 are injected into the core 13 of theelement 11 via the lead 18, cross-talk between the cores 13 and 14 of the element 11 will occur and a back scattered signal will be extracted from the core 13 by the lead 18.
This back scattered signal is directed by the fibre coup-ler or beam splitter ]7 to a detector 22 and a processor23. The back scattered signal detected and processed is dependent upon the amount of cross-talk between the cores 13 and 14 o~ the element 11. At one of the two wave-lengths of the optical signals, cross-talk between the cores is temperature independent. Accordingly, the ex-tracted signals at the two wavelengths can be used to determine temperature and strain at the element 11 by the processor 23.
As will be appreciated, the optical signals iniected into the element 11 after passing through that element are transmitted via the lead 20 to the element 12 where cross-talk will occur between the cores 13 and 14 and a back scattered signal will be directed to the detector 22 and processor 23 as before. As will be appreciated the 1~90 - s-detected signals are identifiable with the particular sensor element 11 or 12 from which they are extracted by the transit time of the pulsed signals.
Whilst the apparatus in Figure 1 is illustrated as S comprising only two sensor element&, it will be appreciated that, further sensor elements of like construction can be serially connected with the illustrated elements 1] and 12 via respective optical fibre leads, the single monomode cores of which preferably connect tl~e core 13 of the element 12 (and thus the core 13 of element 11) to one of the ~ores in each of the further sensor el~ments.
The strain and temperature sensing apparatus 30 illustrated in Figure 2 comprises a single sensor element 31 of like construction to the elements 11 and 12 of apparatus 10. Like the element 11 in apparatus 10, the element 31 is connected via an optical fibre lead 32 having a single monomode core 33 and a fibre coupler or beam splitter 34 to a generating devi~e 35 which generates optic-al signals at two wavelengths, at one of which cross-talk between the cores of the element 31 is temperature inde-pendent.
In the apparatus 30, the end of the sensor element opposite the end thereof connected to the lead 32 is pro-vided with reflecting means~for reflecting optical signals back through the core of the element connected to the single core of the lead 32 and thence via the fibre coupler or beam splitter 34 to a detector 36 and processor 37. The reflecting means may be a mirror chemically grown onto the end face of the element or a mirror surface butted to that end face.
As will be appreciated the optical signal which is extracted from the sensor element by reflection is depen-dent upon the amount of cross-talk which occurs between the cores of the element 31. Accordingly, as in the appa-3~ ratus 10, the processor 37 i6 able to determine the ~905~3 temperature and strain st the element 31 from th~ extrac-ted optical signals.
~ o i~prove the si~nal to noi~e ratio of the appa-ratus, the generating de~ice35 comprises means for modu-lating the optical signals generated thereby and theproce~sor 37 includes a lock-in amplifier or a tuned amp-~ifier.
In this apparatus the generatingdevice 35 may comp-rise two laser sources or alternatively two L.E.D's or two filtered white light sources.
Ihe above two apparatus may be described as being 'single-ended', since the injected and extracted optical signals travel along the same optical fibre leads.
ln Figure 3, there is illustrated an example of a strain and temperature sensing apparatus (designated 40) which may be described as 'double-ended' since it comprises an optical fibre sensor element 4] (whose construction is the same as elements 11 and 12) having respective optical fibre leads 42 and 43 connected to the two ends thereof.
Each of the optical fibre leads 42 and 43 has a single monomode cvre 44 and 45 which are connected to one of the cores of the sensor element 41. As illustrated, a generating means 46 constructed as the generating device 35 of apparatus 30 generates optical signals at two wave-lengths, at one of which cross-talk between the cores of the element 41 is temperature independent, and these opti-cal signals are injected into the element 4] via the lead 42. Lead 43 extracts optical signals from the element 41 and the extracted signals are passed to a detector 47 and processor 48 which determines the temperature and strain at the element 41.
It is to be under6tood that whilst the illustrated sensor elements comprise two cores the~e elements could comprise more than two cores in a common cladding.
It will also be appreciated that in the apparatus ~ 1~9{)S~3 disclosed, optical signals are extracted from the core of the element into which the signals are injected and it is not necessary to extract signals from the other core of the element. This is advantageous in that it allows J
5 conventional single core optical fibre leads to be used for injecting and extracting optical signals.
Advantageously, in order to assist connection between the cores of the optical fibre leads and the sensor elements, one core of the sensor element is posi-10 tioned on the longitudinal axis of the element.
It is to be understood that the strain measured with the sensing apparatus may arise from longitudinal, transverse or radial stresses (or any combination thereof) in the element. In this connection it will be appreciated 15 that radial stresses arise for example when the element is subjected to hydrostatic pressure.
We have also discovered that the sensitivity of the apparatus can be enhanced by using a polarized light source (or sources) the optical fibres, particularly for the leads 18,20;32;42,43, being chosen for their polariza-tion maintaining characteristics. Polarized light may be used in each of the above described embodiments.
Claims (13)
1. A strain and temperature sensing apparatus including: an optical fibre senor 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 optical signals at two wavelengths, at one of which cross-talk between said cores is temperature independent; means for injecting said generated optical signals into said element and for extracting optical signals therefrom; and processing means for determining the temperature and strain at the element from said extracted optical signals.
2. Apparatus as claimed in claim 1, wherein said means for injecting said generated optical signals into said element and for extracting optical signals there-from comprises an optical fibre having a single monomode core which is connected to one of said cores of said element at one end thereof.
3. Apparatus as claimed in claim 2, comprising a further said optical fibre sensor element serially connected to said first-mentioned element by a further said optical fibre having a core connecting the said one core of the first-mentioned element to one of the said cores of said further element.
4. Apparatus as claimed in claim 2, comprising a plurality of further said optical fibre senor elements serially connected to said first-mentioned element by respective further said optical fibres, the cores of said further said optical fibres connecting the said one core of the first-mentioned said element to one of the said cores in each of said further elements.
5. Apparatus as claimed in claim 1, wherein said generating means are arranged to generate optical pulses.
6. Apparatus as claimed in claim 1, wherein said generating means comprises two laser sources.
7. Apparatus as claimed in claim 2, comprising reflecting means provided at one end of said senor element for reflecting optical signals back through said one core thereof into said core of said optical fibre.
8. Apparatus as claimed in claim 1, wherein said means for injecting said generated optical signals into said element and for extracting optical signals therefrom comprises two optical fibres each having a single mono-mode core, one of said fibres being connected to one end of the element for injecting said generated optical signals into said element, and the other of said fibres being connected to the other end of said element for extracting optical signals therefrom.
9. Apparatus as claimed in claim 8, wherein one of the said cores of said element is connected to the said cores of both optical fibres.
10. Apparatus as claimed in claim 7, wherein said generating means is selected from the group comprising:
two laser sources, two L.E.D's and two filtered white light sources.
two laser sources, two L.E.D's and two filtered white light sources.
11. Apparatus as claimed in claim 7, wherein said generating means comprises means for modulating the optical signals generated thereby.
12. Apparatus as claimed in claim 1, wherein said generating means comprises a layers of polarized light, and said means for injecting and extracting optical signals are polarization maintaining optical fibres.
13. A method of sensing strain and temperature comprising injecting optical signals at two wavelengths into an optical fibre 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, one of said wavelengths being such that cross-talk between the cores is temperature independent; extracting optical signals from the element; and processing the extracted signals to determine the temperature and strain of said element.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8614960 | 1986-06-19 | ||
| GB8614960A GB2197946B (en) | 1986-06-19 | 1986-06-19 | Sensing strain and temperature |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1290589C true CA1290589C (en) | 1991-10-15 |
Family
ID=10599721
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000539916A Expired - Lifetime CA1290589C (en) | 1986-06-19 | 1987-06-17 | Sensing strain and temperature |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US4842403A (en) |
| EP (1) | EP0250194B1 (en) |
| JP (1) | JPS6340827A (en) |
| BR (1) | BR8703506A (en) |
| CA (1) | CA1290589C (en) |
| DE (1) | DE3777889D1 (en) |
| ES (1) | ES2031503T3 (en) |
| GB (1) | GB2197946B (en) |
Families Citing this family (29)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3804135A1 (en) * | 1988-02-11 | 1989-08-24 | Felten & Guilleaume Energie | METHOD FOR CONTINUOUS DAMPING MEASUREMENT OF FOCUS SENSORS WITH ONLY ONE ACCESSIBLE END |
| US5144690A (en) * | 1990-12-03 | 1992-09-01 | Corning Incorporated | Optical fiber sensor with localized sensing regions |
| US5513913A (en) * | 1993-01-29 | 1996-05-07 | United Technologies Corporation | Active multipoint fiber laser sensor |
| JP2661856B2 (en) * | 1993-03-26 | 1997-10-08 | 株式会社神戸製鋼所 | Temperature distribution measurement method |
| FR2706607B1 (en) * | 1993-06-15 | 1995-07-21 | Thomson Csf | Reconfigurable multi-point temperature sensor. |
| US5446280A (en) * | 1993-08-31 | 1995-08-29 | Center For Innovative Technology | Split-spectrum self-referenced fiber optic sensor |
| KR100255961B1 (en) * | 1994-03-11 | 2000-05-01 | 아끼구사 나오유끼 | Method and device for measuring physical quantity, method for fabricating semiconductor device, and method and device for measuring wavelength |
| DE4423104A1 (en) * | 1994-07-01 | 1996-01-04 | Leon Helma Christina | Pressure sensitive sensor system |
| US5649934A (en) * | 1994-12-06 | 1997-07-22 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Apparatus for assisting childbirth |
| US5775808A (en) * | 1996-06-19 | 1998-07-07 | Applied Materials, Inc. | Apparatus for real-time, in situ measurement of temperature and a method of fabricating and using same |
| US6056436A (en) * | 1997-02-20 | 2000-05-02 | University Of Maryland | Simultaneous measurement of temperature and strain using optical sensors |
| US6057911A (en) * | 1997-11-17 | 2000-05-02 | Northrop Grumman Corporation | Fiber optic fabry-perot sensor for measuring absolute strain |
| GB9820467D0 (en) | 1998-09-18 | 1998-11-11 | Europ Economic Community | Sensing apparatus and a measurment method |
| GB9828469D0 (en) * | 1998-12-24 | 1999-02-17 | British Aerospace | A modulated fibre bragg grating strain gauge assembly for absolute gauging of strain |
| DE19913800C2 (en) * | 1999-03-26 | 2002-02-28 | Telegaertner Geraetebau Gmbh | Arrangement for evaluating narrow-band optical signals |
| GB0021976D0 (en) * | 2000-09-07 | 2000-10-25 | Optomed As | Multi-parameter fiber optic probes |
| GB0021975D0 (en) | 2000-09-07 | 2000-10-25 | Optomed As | Filter optic probes |
| US6659640B2 (en) * | 2001-04-26 | 2003-12-09 | The United States Of America As Represented By The Secretary Of The Navy | Fiber optic temperature measurement system and method |
| TW500912B (en) * | 2001-11-30 | 2002-09-01 | Nat Chao Tung University Libra | Method to sense the stress and temperature distribution of fiber simultaneously |
| DE102010044583B4 (en) * | 2010-09-07 | 2012-05-10 | Krohne Messtechnik Gmbh | Deflection measuring device according to the interferometry principle |
| US9170172B2 (en) * | 2011-08-23 | 2015-10-27 | The Boeing Company | Composite structure having an embedded sensing system |
| WO2013134575A1 (en) * | 2012-03-07 | 2013-09-12 | Ofs Fitel, Llc | Grating-based sensor |
| CA2815788C (en) * | 2012-07-31 | 2016-10-11 | The Boeing Company | Composite structure having an embedded sensing system |
| DE102013205205A1 (en) * | 2013-03-25 | 2014-10-09 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Fiber optic sensor and its use |
| KR101575869B1 (en) | 2014-05-26 | 2015-12-09 | 한국광기술원 | PLC type physical quanty sensing apparatus |
| US9240262B1 (en) * | 2014-07-21 | 2016-01-19 | General Electric Company | Systems and methods for distributed pressure sensing |
| WO2019073424A1 (en) * | 2017-10-11 | 2019-04-18 | Auckland Uniservices Limited | A deformation sensing device, apparatus and system |
| JP7145824B2 (en) * | 2019-08-22 | 2022-10-03 | 古河電気工業株式会社 | External force detector and optical fiber sensor |
| CN110631735A (en) * | 2019-10-22 | 2019-12-31 | 武汉理工光科股份有限公司 | Pipeline temperature measurement system and method based on distributed sensing optical fiber |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE411955B (en) * | 1978-06-02 | 1980-02-11 | Asea Ab | FIBEROPTICAL METDON WITH MOST TWO FIBERS |
| US4151747A (en) * | 1978-06-21 | 1979-05-01 | Electric Power Research Institute, Inc. | Monitoring arrangement utilizing fiber optics |
| US4295738A (en) * | 1979-08-30 | 1981-10-20 | United Technologies Corporation | Fiber optic strain sensor |
| US4295739A (en) * | 1979-08-30 | 1981-10-20 | United Technologies Corporation | Fiber optic temperature sensor |
| US4298794A (en) * | 1979-08-30 | 1981-11-03 | United Technologies Corporation | Fiber optic hot spot detector |
| US4420251A (en) * | 1980-05-05 | 1983-12-13 | Rockwell International Corporation | Optical deformation sensor |
| JPS57191798A (en) * | 1981-05-19 | 1982-11-25 | Furukawa Electric Co Ltd | Detection of value to be measured employing multi-core optical fiber |
| US4653906A (en) * | 1984-08-13 | 1987-03-31 | United Technologies Corporation | Spatially resolving fiber-optic crosstalk strain sensor |
| JPH067049B2 (en) * | 1984-08-13 | 1994-01-26 | ユナイテツド テクノロジ−ズ コ−ポレ−シヨン | Optical fiber strainmeter for dispersive and spaced analysis |
| US4773753A (en) * | 1985-09-03 | 1988-09-27 | Daiichi Denshi Kogyo Kabushiki Kaisha | Fiber sensor |
-
1986
- 1986-06-19 GB GB8614960A patent/GB2197946B/en not_active Expired
-
1987
- 1987-06-15 DE DE8787305289T patent/DE3777889D1/en not_active Expired - Lifetime
- 1987-06-15 EP EP87305289A patent/EP0250194B1/en not_active Expired
- 1987-06-15 ES ES198787305289T patent/ES2031503T3/en not_active Expired - Lifetime
- 1987-06-17 CA CA000539916A patent/CA1290589C/en not_active Expired - Lifetime
- 1987-06-19 JP JP62151554A patent/JPS6340827A/en active Granted
- 1987-06-19 BR BR8703506A patent/BR8703506A/en not_active IP Right Cessation
-
1988
- 1988-12-05 US US07/281,963 patent/US4842403A/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0579131B2 (en) | 1993-11-01 |
| GB8614960D0 (en) | 1986-07-23 |
| EP0250194A2 (en) | 1987-12-23 |
| JPS6340827A (en) | 1988-02-22 |
| EP0250194B1 (en) | 1992-04-01 |
| US4842403A (en) | 1989-06-27 |
| DE3777889D1 (en) | 1992-05-07 |
| EP0250194A3 (en) | 1989-08-23 |
| BR8703506A (en) | 1988-03-22 |
| GB2197946B (en) | 1989-12-20 |
| ES2031503T3 (en) | 1992-12-16 |
| GB2197946A (en) | 1988-06-02 |
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