WO1992007236A1 - Reflecteur a fibres optiques - Google Patents
Reflecteur a fibres optiques Download PDFInfo
- Publication number
- WO1992007236A1 WO1992007236A1 PCT/GB1991/001820 GB9101820W WO9207236A1 WO 1992007236 A1 WO1992007236 A1 WO 1992007236A1 GB 9101820 W GB9101820 W GB 9101820W WO 9207236 A1 WO9207236 A1 WO 9207236A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- fibre
- optical fibre
- light
- reflector
- optical
- Prior art date
Links
- 239000013307 optical fiber Substances 0.000 title claims abstract description 43
- 230000003287 optical effect Effects 0.000 claims abstract description 12
- 230000008878 coupling Effects 0.000 claims abstract description 3
- 238000010168 coupling process Methods 0.000 claims abstract description 3
- 238000005859 coupling reaction Methods 0.000 claims abstract description 3
- 239000000835 fiber Substances 0.000 claims description 39
- 230000001427 coherent effect Effects 0.000 claims description 6
- 230000005540 biological transmission Effects 0.000 claims description 4
- 238000001514 detection method Methods 0.000 claims description 4
- 239000000853 adhesive Substances 0.000 claims description 2
- 230000001070 adhesive effect Effects 0.000 claims description 2
- 230000001419 dependent effect Effects 0.000 claims 1
- 238000010276 construction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000003491 array Methods 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000000586 desensitisation Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000001771 vacuum deposition Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/353—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre
- G01D5/35383—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells influencing the transmission properties of an optical fibre using multiple sensor devices using multiplexing techniques
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H9/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means
- G01H9/004—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by using radiation-sensitive means, e.g. optical means using fibre optic sensors
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/241—Light guide terminations
- G02B6/243—Light guide terminations as light absorbers
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/2804—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers
Definitions
- This invention relates to optical fibre reflectors for use in sensing systems such as for example are used in the detection of acoustic pressure waves e.g. hydrophone applications or temperature sensing.
- Reflectometric arrays of interferometric sensors are formed by constructing a line of fibre transducers separated by a semi reflecting element such as is described in British Patent Specification No. 2126820B.
- an optical fibre reflector comprising a pair of fibres interconnected intermediate of their ends to permit optical coupling therebetween, one of the fibres having a light reflective termination at one end and a light dispersive termination at the opposite end.
- the invention also includes an optical sensing system comprising an optical fibre arranged to be subjected along its length to fibre deforming forces during operation of the system and means for producing coherent light signals for transmission along said optical fibre, in which the optical fibre is provided along its length with a plurality of equally spaced optical fibre reflectors as previously defined so that a small proportion of each light signal being transmitted along the fibre will be reflected back along the fibre from each of the reflectors whereby each reflected light signal after the first interferes with either the previously reflected signal from the preceding reflector or a reference light signal of the same frequency or a frequency with a constant difference frequency to the transmitted light signal to produce an electrical signal in square law photo-detection means of the system, the difference between respective electrical signals corresponding to successive fibre elements being dependant upon the length of the fibre elements so that changes in length of these elements produced by the incidence of deforming forces will result in changes in the electrical signals which will be detected.
- FIG 1 shows an optical fibre reflector constructed in accordance with the invention employing two equal diameter fibres
- Figure 3 shows a schematic diagram of a sensing system constructed in accordance with a second aspect of the invention.
- Figures 4 and 5 show pulse diagrams relating to alternative systems for sensing optical fibre deformation.
- the drawing of Figure 1 shows two optical fibres 10 and 11 which may be single or multimode and are of equal diameter.
- the fibre 10 in this example is shown to be straight, although this is not essential, and is intended to form the main transmission path for coherent light pulses.
- the fibre 11 in this example is shown curved, although this is not essential, and forms a reflector.
- the second fibre adjoins the first fibre and is optically coupled thereto by for example fusion.
- One end of the fibre 11 is provided with a reflective mirror 12 which may be a discrete device or alternatively the end surface may be adapted to reflect light back along the fibre by for example silvering of the end surface e.g. by dipping in a silver solution or vacuum coating by sputtering.
- the other end of the fibre 11 is arranged to be dispersive so that significant light is not reflected.
- Such dispersion can be effected by forming that end by a bad break of the fibre and/or by applying an adhesive which solidifies thereon and is light dispersive.
- each two-pulse light signal reaches the first reflector 25 a small proportion of the signal will be reflected back along the fibre 24 to the beam splitter 23 which directs the signal to a photodetector 32.
- the remaining part of the two-pulse signals travels on to reflector 26 at which a further small proportion thereof will be reflected back along the optical fibre 24 to the detector 32.
- This procedure continues until that part of the two-pulse signal remaining reaches the last of the reflectors 31 and a small proportion of this signal is again reflected back along the optical fibre to the detector 32.
- a further two-pulse optical transmission is then made and the cycle repeated.
- FIG. 4 of the drawing shows by way of example reflections of the two-pulse signals from the reflectors 25, 26 and 27.
- the reflection from the second reflector 26 in the present example is delayed with respect to the reflection from the first reflector 25 by time T.
- the delay between the reflections is such that there is total coincidence or at least some overlap between the reflected pulse or frequency F of a later reflected signal with the pulse of frequency F + AF of the preceding reflected signal.
- the reflected pulses are heterodyned in the square law photodetector 32 to produce beat or modulated signals as shown and the phase modulation of these signal will vary in dependence upon variations in length of the optical fibre elements. Accordingly, by detecting and measuring the phase modulation of the beat signals by means of a phase detector 33 changes in length of the optical fibre elements and thus deformation forces acting on these elements can be measured.
- FIG. 5 of the drawings shows the pulse diagram of an alternative sensing system in which the pulsed laser will produce at predetermined intervals one or two closely spaced pulses of the same frequency which constitute the signals fed to the optical fibre 24 ( Figure 3) without the intervention of the optical switch means 22 ( Figure 3) .
- the signals reflected from the reflectors 25, 26 and 27 will be as shown in Figure 5.
- the reflected signals are homodyned and the changes in amplitude of the electrical signals produced by changes in length of the optical fibre elements will be detected by the photodetector 32 ( Figure 3) .
- the phase detector 33 is not required for this embodiment.
- the free end of the optical fibre including the reflectors 25 to 31 may be trailed through the water and provide a beamforming acoustic wave sensor array which responds to acoustic waves impinging on the optical fibre sensing elements to produce variations in the lengths thereof which will be measured in the manner described.
- a beamforming acoustic wave sensor array which responds to acoustic waves impinging on the optical fibre sensing elements to produce variations in the lengths thereof which will be measured in the manner described.
- this enables a single optical fibre sensor to be used as a beamforming array instead of using a plurality of separate sensors which can be inconvenient and expensive.
- the simple and relatively cheap provision of a beamforming acoustic sensor array as described also has the advantage of requiring access to one end only of the optical fibre which facilitates trailing of the fibre behind a vessel and which is compatible with the desensitisation of that part of the optical fibre between the signal generating and phase detection means and the fibre sensing elements.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
Abstract
Un réflecteur à fibres optiques comprend une paire de fibres (10, 11) mutuellement reliées en un point intermédiaire par rapport à leurs extrémités afin de permettre un couplage optique entre elles. L'une des fibres (11) comporte une terminaison réflectrice (12) à une extrémité et une terminaison dispersant la lumière à l'extrémité opposée.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9022739A GB2248928A (en) | 1990-10-19 | 1990-10-19 | Optical fibre reflector |
GB9022739.8 | 1990-10-19 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1992007236A1 true WO1992007236A1 (fr) | 1992-04-30 |
Family
ID=10683990
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/GB1991/001820 WO1992007236A1 (fr) | 1990-10-19 | 1991-10-17 | Reflecteur a fibres optiques |
Country Status (3)
Country | Link |
---|---|
AU (1) | AU8730891A (fr) |
GB (1) | GB2248928A (fr) |
WO (1) | WO1992007236A1 (fr) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2734373A1 (fr) * | 1995-05-19 | 1996-11-22 | Gaz De France | Coupleur optique a taux de derivation variable et utilisation en tant que capteur |
EP0895075A3 (fr) * | 1997-07-31 | 1999-10-20 | Litton Systems, Inc. | Réseau de capteurs de pression optiques, non-acoustiques, à multiplexage par division de temps |
WO2000012977A1 (fr) * | 1998-09-01 | 2000-03-09 | Input/Output, Inc. | Systeme optoacoustique recursif de detection sismique |
EP1912049A1 (fr) * | 2006-10-13 | 2008-04-16 | AT&T Corp. | Procédé et appareil pour la capture acoustique à l'aide d'impulsions optiques multiples |
EP1912050A1 (fr) * | 2006-10-13 | 2008-04-16 | AT&T Corp. | Procédé et appareil pour la capture acoustique à l'aide d'impulsions optiques multiples |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5297224A (en) * | 1992-08-14 | 1994-03-22 | Litton Systems, Inc. | Optically switched sensor array |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2152689A (en) * | 1984-01-11 | 1985-08-07 | Plessey Co Plc | Optical fibre sensing apparatus |
US4545253A (en) * | 1983-08-29 | 1985-10-08 | Exxon Production Research Co. | Fiber optical modulator and data multiplexer |
US4673270A (en) * | 1985-06-28 | 1987-06-16 | Amp Incorporated | Channel add/drop filter-coupler |
EP0231635A2 (fr) * | 1986-01-07 | 1987-08-12 | Litton Systems, Inc. | Dispositif de dérivation pour ligne de bus bidirectionnelle à fibre optique |
EP0277698A2 (fr) * | 1987-02-02 | 1988-08-10 | Litton Systems, Inc. | Méthode et arrangement de mesure avec des détecteurs fibreoptiques |
-
1990
- 1990-10-19 GB GB9022739A patent/GB2248928A/en not_active Withdrawn
-
1991
- 1991-10-17 WO PCT/GB1991/001820 patent/WO1992007236A1/fr active Application Filing
- 1991-10-17 AU AU87308/91A patent/AU8730891A/en not_active Abandoned
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4545253A (en) * | 1983-08-29 | 1985-10-08 | Exxon Production Research Co. | Fiber optical modulator and data multiplexer |
GB2152689A (en) * | 1984-01-11 | 1985-08-07 | Plessey Co Plc | Optical fibre sensing apparatus |
US4673270A (en) * | 1985-06-28 | 1987-06-16 | Amp Incorporated | Channel add/drop filter-coupler |
EP0231635A2 (fr) * | 1986-01-07 | 1987-08-12 | Litton Systems, Inc. | Dispositif de dérivation pour ligne de bus bidirectionnelle à fibre optique |
EP0277698A2 (fr) * | 1987-02-02 | 1988-08-10 | Litton Systems, Inc. | Méthode et arrangement de mesure avec des détecteurs fibreoptiques |
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2734373A1 (fr) * | 1995-05-19 | 1996-11-22 | Gaz De France | Coupleur optique a taux de derivation variable et utilisation en tant que capteur |
EP0895075A3 (fr) * | 1997-07-31 | 1999-10-20 | Litton Systems, Inc. | Réseau de capteurs de pression optiques, non-acoustiques, à multiplexage par division de temps |
WO2000012977A1 (fr) * | 1998-09-01 | 2000-03-09 | Input/Output, Inc. | Systeme optoacoustique recursif de detection sismique |
EP1912049A1 (fr) * | 2006-10-13 | 2008-04-16 | AT&T Corp. | Procédé et appareil pour la capture acoustique à l'aide d'impulsions optiques multiples |
EP1912050A1 (fr) * | 2006-10-13 | 2008-04-16 | AT&T Corp. | Procédé et appareil pour la capture acoustique à l'aide d'impulsions optiques multiples |
US7742157B2 (en) | 2006-10-13 | 2010-06-22 | At&T Intellectual Property Ii, L.P. | Method and apparatus for acoustic sensing using multiple optical pulses |
US7764363B2 (en) | 2006-10-13 | 2010-07-27 | At&T Intellectual Property Ii, L.P. | Method and apparatus for acoustic sensing using multiple optical pulses |
US9768863B2 (en) | 2006-10-13 | 2017-09-19 | At&T Intellectual Property Ii, L.P. | Method and apparatus for acoustic sensing using multiple optical pulses |
US9787394B2 (en) | 2006-10-13 | 2017-10-10 | At&T Intellectual Property Ii, L.P. | Method and apparatus for acoustic sensing using multiple optical pulses |
US10447388B2 (en) | 2006-10-13 | 2019-10-15 | At&T Intellectual Property Ii, L.P. | Method and apparatus for detecting a disturbance in a medium |
US10454573B2 (en) | 2006-10-13 | 2019-10-22 | At&T Intellectual Property Ii, L.P. | Method and apparatus for detecting a disturbance in a medium |
US10623091B2 (en) | 2006-10-13 | 2020-04-14 | At&T Intellectual Property Ii, L.P. | Method and apparatus for detecting a disturbance in a medium using threshold based detection |
US10623092B2 (en) | 2006-10-13 | 2020-04-14 | At&T Intellectual Property Ii, L.P. | Method and apparatus for detecting a disturbance in a medium using threshold based detection |
US10972180B2 (en) | 2006-10-13 | 2021-04-06 | At&T Intellectual Property Ii, L.P. | Method and apparatus for detecting a disturbance in a medium |
US10972181B2 (en) | 2006-10-13 | 2021-04-06 | At&T Intellectual Property Ii, L.P. | Method and apparatus for detecting a disturbance in a medium |
US11431409B2 (en) | 2006-10-13 | 2022-08-30 | At&T Intellectual Property Ii, L.P. | Method and apparatus for detecting a disturbance in a medium based on shifted filtered phase information for a plurality of fixed locations |
US11438059B2 (en) | 2006-10-13 | 2022-09-06 | At&T Intellectual Property Ii, L.P. | Method and apparatus for detecting a disturbance in a medium based on shifted filtered phase information for a plurality of locations |
Also Published As
Publication number | Publication date |
---|---|
GB2248928A (en) | 1992-04-22 |
GB9022739D0 (en) | 1991-06-12 |
AU8730891A (en) | 1992-05-20 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4302835A (en) | Multiple terminal passive multiplexing apparatus | |
US4653916A (en) | Optical sensing systems | |
US4649529A (en) | Multi-channel fiber optic sensor system | |
US4297887A (en) | High-sensitivity, low-noise, remote optical fiber | |
GB2126820A (en) | An optical sensing system | |
US5510890A (en) | Laser radar with reference beam storage | |
GB2165118A (en) | OTDR for sensing distortions in optical fibres | |
GB2147758A (en) | Optical detecting and/or measuring | |
GB2136113A (en) | Improvements Relating to Optical Sensing Systems | |
US5071214A (en) | Interferometric fibre optic network | |
EP0183502B1 (fr) | Systèmes pour la génération d'impulsions optiques | |
WO1992007236A1 (fr) | Reflecteur a fibres optiques | |
GB2147759A (en) | Optical sensor | |
US5227624A (en) | Optical sensing systems with plural wavelengths and wavelength sensitive sensors | |
GB2190262A (en) | Optical fibre sensor | |
GB2152689A (en) | Optical fibre sensing apparatus | |
Dakin et al. | Optical fibre hydrophone array-recent progress | |
EP0299638A2 (fr) | Dispositifs de transducteurs optiques | |
EP0326199A2 (fr) | Capteur optique | |
GB2248498A (en) | Variable gain optical sensing system | |
JP3004775B2 (ja) | 光音響センサアレイシステム | |
GB2157842A (en) | Optical fibre sensing apparatus | |
GB2190187A (en) | Optical fibre sensors | |
GB2250593A (en) | Optical sensing system | |
JPS63292033A (ja) | 光ファイバの片端測定方法 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AK | Designated states |
Kind code of ref document: A1 Designated state(s): AU CA JP US |
|
AL | Designated countries for regional patents |
Kind code of ref document: A1 Designated state(s): AT BE CH DE DK ES FR GB GR IT LU NL SE |
|
122 | Ep: pct application non-entry in european phase | ||
NENP | Non-entry into the national phase |
Ref country code: CA |