CA1093858A - Fibre optic cable signal detector and fault locator - Google Patents
Fibre optic cable signal detector and fault locatorInfo
- Publication number
- CA1093858A CA1093858A CA343,763A CA343763A CA1093858A CA 1093858 A CA1093858 A CA 1093858A CA 343763 A CA343763 A CA 343763A CA 1093858 A CA1093858 A CA 1093858A
- Authority
- CA
- Canada
- Prior art keywords
- optic cable
- fibre optic
- signal detector
- fibre
- fault locator
- 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
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/07—Arrangements for monitoring or testing transmission systems; Arrangements for fault measurement of transmission systems
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
- G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Examining Or Testing Airtightness (AREA)
Abstract
Fibre Optic Cable Signal Detector and Fault Locator Abstract Based on the spectrophone principle, an acoustic transducer may be mounted on a fibre optic cable to detect modulated light messages being transmitted along the cable. The same device may also be used as a movable indicator to precisely locate and identify fibre structural discontinuities, bends and ruptures in a simple manner.
Description
- 1 .a~3~
This invention relates to fibre optics and more particularly to a device which enables the optical signal conducted by the fibre to be measured by a pressure or heat sensor.
The principle and putting into p~actice of signal -transmission along a fibre, usually a quartz fibre9 by modulation of ligh-t is well known. A major advantage of fibre light transmission is the high bar~clwidth, typically 200 obtained versus the 10 MH~ normal wi-th metal coaxial cable. Optical fibres also differ from their conventional communication counterpar-ts in that the fibre is entirely an insulator rather than a conductor. Furthermore since the light signal travels within the fibre, alw~ys reflecting inwards when it strikes the fibre outer boundary -there is no light emitted from the fibre and hence no signal along its length except at the very end. Since the fibre is generally covered in a mechanically protec-ti~e, opaquc sheath there is even less likelihood that llgh-t will escape. Because, of this flbre optic cables are said to be very private since there is no analogy with inductive coupling which may be used with metal cable in order to intercept messages being transmitted along it. This privacy al90 makes it difficult to locate the ~xact po~ition o~ breaks in the optical fibre within the cable sheath.
To a lesser extent break detection is also a problem in metal communication lines though here the pos3ibility of visual inspection exlsts, at least for bare twisted-pair lines. One common solution is time domain reflectometry whereby an electrical pulse is sent down the line and its reflection monitored.
The reflected pulse will indicate -the presence of breaks or discontinuities.
This method may also be employed wi-th optical fibres, however, a disad~antage in bo-th cases is that intricate9 expensive equipment is needed particularly if the break or discontinuity is to be located precisely within a fraction of a centimetre~
We propose a new solution to the problem of the interception of modulated light signals and the location of defects, bends or ruptures i~ fibre optical cables. Our solu-tion arises from consideration o~ the optoacoustic cell (some synonyms ares spectrophone, photoacoustic cell etc.) which essentiall~
m~asures heat or pressure generated by the passage of light t~ough a medium X;,, ~4 ': ,, ' , " ' ,.: " . ::
- ` ` z ~
which it contains. In its common form the optoacoustic cell consists of a container having glass windows on each end, an integral pressure transducer such as a microphone~ a light source with or withou-t a chopper and conventional electronic readout instrumentation. For our applicatLon we oonsider -the light fibre to be at once -the optoacoustic cell container, medium and end windows. The pressure transducer (or strain gauge or heat sensor) may be glued, clamped or otherwise brought into mechanical contact with the fibre at any point on its lengbh. The transducer, which may be a common pie~oceramic transducer ele~eNt, need not contac-t the flbre directly but instead may contact the outer sheath of the cable.
Since the fibre optic cable may be many hundreds of metres long the optoacoustic cell has now changed from a finite, closed container to a nearly infinite, open one. As ligh-t passes along thc fibre, either ln the Porm of a 50 discrete pulse or as a continuous modulation wave, it will cause -khermal and stress waves to be created which may be detected by the transducer elemen-t joined to the fibre. Thus we have observed a 100 ~V signal from a transducer glued to a light fibre when light from a flashlamp was sent along it~
The light sent along the fibre could be a test signal used to located fibre defects or it could simply be the normal modulated light communication slgnal which the fibre carries. ~y moving the transducer along the optical fibre an anomalous signal could be detected at the point where the fibre has a defect, microbend or rupture since the acoustic wave generated there would differ considerably from that due to a normal fibre section.
Figure 1 is a plan view of the Fibre Optic Cable Signal Detector.
Item 1 is a fibre optic cable to which glue is joined (2). Also joined to the glue is a piezoceramic transducer (3).
Figure 2 is an edge view of the same device.
~' ~
:: .
This invention relates to fibre optics and more particularly to a device which enables the optical signal conducted by the fibre to be measured by a pressure or heat sensor.
The principle and putting into p~actice of signal -transmission along a fibre, usually a quartz fibre9 by modulation of ligh-t is well known. A major advantage of fibre light transmission is the high bar~clwidth, typically 200 obtained versus the 10 MH~ normal wi-th metal coaxial cable. Optical fibres also differ from their conventional communication counterpar-ts in that the fibre is entirely an insulator rather than a conductor. Furthermore since the light signal travels within the fibre, alw~ys reflecting inwards when it strikes the fibre outer boundary -there is no light emitted from the fibre and hence no signal along its length except at the very end. Since the fibre is generally covered in a mechanically protec-ti~e, opaquc sheath there is even less likelihood that llgh-t will escape. Because, of this flbre optic cables are said to be very private since there is no analogy with inductive coupling which may be used with metal cable in order to intercept messages being transmitted along it. This privacy al90 makes it difficult to locate the ~xact po~ition o~ breaks in the optical fibre within the cable sheath.
To a lesser extent break detection is also a problem in metal communication lines though here the pos3ibility of visual inspection exlsts, at least for bare twisted-pair lines. One common solution is time domain reflectometry whereby an electrical pulse is sent down the line and its reflection monitored.
The reflected pulse will indicate -the presence of breaks or discontinuities.
This method may also be employed wi-th optical fibres, however, a disad~antage in bo-th cases is that intricate9 expensive equipment is needed particularly if the break or discontinuity is to be located precisely within a fraction of a centimetre~
We propose a new solution to the problem of the interception of modulated light signals and the location of defects, bends or ruptures i~ fibre optical cables. Our solu-tion arises from consideration o~ the optoacoustic cell (some synonyms ares spectrophone, photoacoustic cell etc.) which essentiall~
m~asures heat or pressure generated by the passage of light t~ough a medium X;,, ~4 ': ,, ' , " ' ,.: " . ::
- ` ` z ~
which it contains. In its common form the optoacoustic cell consists of a container having glass windows on each end, an integral pressure transducer such as a microphone~ a light source with or withou-t a chopper and conventional electronic readout instrumentation. For our applicatLon we oonsider -the light fibre to be at once -the optoacoustic cell container, medium and end windows. The pressure transducer (or strain gauge or heat sensor) may be glued, clamped or otherwise brought into mechanical contact with the fibre at any point on its lengbh. The transducer, which may be a common pie~oceramic transducer ele~eNt, need not contac-t the flbre directly but instead may contact the outer sheath of the cable.
Since the fibre optic cable may be many hundreds of metres long the optoacoustic cell has now changed from a finite, closed container to a nearly infinite, open one. As ligh-t passes along thc fibre, either ln the Porm of a 50 discrete pulse or as a continuous modulation wave, it will cause -khermal and stress waves to be created which may be detected by the transducer elemen-t joined to the fibre. Thus we have observed a 100 ~V signal from a transducer glued to a light fibre when light from a flashlamp was sent along it~
The light sent along the fibre could be a test signal used to located fibre defects or it could simply be the normal modulated light communication slgnal which the fibre carries. ~y moving the transducer along the optical fibre an anomalous signal could be detected at the point where the fibre has a defect, microbend or rupture since the acoustic wave generated there would differ considerably from that due to a normal fibre section.
Figure 1 is a plan view of the Fibre Optic Cable Signal Detector.
Item 1 is a fibre optic cable to which glue is joined (2). Also joined to the glue is a piezoceramic transducer (3).
Figure 2 is an edge view of the same device.
~' ~
:: .
Claims (7)
1. A fibre optic cable signal detector and fault locator comprising a fibre optic cable, a pulsed light input, and a pressure transducer, said transducer mechanically joined to the fibre optic cable, said light source producing thermal and stress waves through absorption in the fibre optic cable, said waves passing through the mechanical joint to the transducer causing a transducer signal related to the pulsed light input.
2. A fibre optic cable signal detector and fault locator as defined in claim 1 where the input is periodically modulated light.
3. A fibre optic cable signal detector and fault locator as defined in claim 1 where the fibre optic cable is covered in a protective sheath and the pressure transducer is mechanically joined to the fibre optic cable.
4. A fibre optic cable signal detector and fault locator as defined in claim 1 where the pressure transducer is a heat sensor.
5. A fibre optic cable signal detector and fault locator as defined in claim 1 where the magnitude of the light input is measured permitting the transducer signal to indicate absorption in the cable, also called transmission loss.
6. A fibre optic cable signal detector and fault locator as defined in claim 1 used to identify and locate at a point any discontinuity, microbend, defect or rupture in an optical fibre.
7. A fibre optic cable signal detector and fault locator as defined in claim 1 where the fibre optic cable is an optical fibre cable connector and the transmission loss is measured.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA343,763A CA1093858A (en) | 1980-01-16 | 1980-01-16 | Fibre optic cable signal detector and fault locator |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA343,763A CA1093858A (en) | 1980-01-16 | 1980-01-16 | Fibre optic cable signal detector and fault locator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1093858A true CA1093858A (en) | 1981-01-20 |
Family
ID=4116050
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA343,763A Expired CA1093858A (en) | 1980-01-16 | 1980-01-16 | Fibre optic cable signal detector and fault locator |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1093858A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0069930A1 (en) * | 1981-07-02 | 1983-01-19 | Sumitomo Electric Industries Limited | Monitor device for laser systems transmitting laser light through optical fibers |
| WO2005020478A1 (en) * | 2003-08-20 | 2005-03-03 | At & T Corp. | Method, apparatus and system for minimally intrusive fiber identification |
-
1980
- 1980-01-16 CA CA343,763A patent/CA1093858A/en not_active Expired
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0069930A1 (en) * | 1981-07-02 | 1983-01-19 | Sumitomo Electric Industries Limited | Monitor device for laser systems transmitting laser light through optical fibers |
| WO2005020478A1 (en) * | 2003-08-20 | 2005-03-03 | At & T Corp. | Method, apparatus and system for minimally intrusive fiber identification |
| US8023774B2 (en) | 2003-08-20 | 2011-09-20 | At&T Intellectual Property Ii, L.P. | Method, apparatus and system for minimally intrusive fiber identification |
| US8811780B2 (en) | 2003-08-20 | 2014-08-19 | At&T Intellectual Property Ii, L.P. | Method, apparatus and system for minimally intrusive fiber identification |
| US9243973B2 (en) | 2003-08-20 | 2016-01-26 | At&T Intellectual Property Ii, L.P. | Method, apparatus and system for minimally intrusive fiber identification |
| US9534982B2 (en) | 2003-08-20 | 2017-01-03 | At&T Intellectual Property Ii, L.P. | Method, apparatus and system for minimally intrusive fiber identification |
| US9797807B2 (en) | 2003-08-20 | 2017-10-24 | At&T Intellectual Property Ii, L.P. | Method, apparatus and system for minimally intrusive fiber identification |
| US10168247B2 (en) | 2003-08-20 | 2019-01-01 | At&T Intellectual Property Ii, L.P. | Method, apparatus and system for minimally intrusive fiber identification |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |