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WO1996008695A1 - Capteurs optiques et procede de production de capteurs a detection de mode pour fibres optiques - Google Patents

Capteurs optiques et procede de production de capteurs a detection de mode pour fibres optiques Download PDF

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Publication number
WO1996008695A1
WO1996008695A1 PCT/AU1995/000568 AU9500568W WO9608695A1 WO 1996008695 A1 WO1996008695 A1 WO 1996008695A1 AU 9500568 W AU9500568 W AU 9500568W WO 9608695 A1 WO9608695 A1 WO 9608695A1
Authority
WO
WIPO (PCT)
Prior art keywords
fibre
singlemode
sensor
multimode
waveguide
Prior art date
Application number
PCT/AU1995/000568
Other languages
English (en)
Inventor
Edward Tapanes
Original Assignee
Future Fibre Technologies Pty. Ltd.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Future Fibre Technologies Pty. Ltd. filed Critical Future Fibre Technologies Pty. Ltd.
Priority to GB9704123A priority Critical patent/GB2307551B/en
Priority to CA002198593A priority patent/CA2198593C/fr
Priority to AU33768/95A priority patent/AU688113B2/en
Publication of WO1996008695A1 publication Critical patent/WO1996008695A1/fr

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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
    • 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
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/22—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers
    • G01L5/226—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers to manipulators, e.g. the force due to gripping
    • G01L5/228—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes for measuring the force applied to control members, e.g. control members of vehicles, triggers to manipulators, e.g. the force due to gripping using tactile array force sensors

Definitions

  • This invention relates to an optical sensor and method for producing modalmetric waveguide sensors.
  • Optical devices are commonly used in industry and science and include laser cavities, waveguides, lenses and other optical elements. Such optical devices are used in a variety of instruments and installations.
  • Photonics technology has revolutionised the communications and sensor fields. This is mainly due to the rapid development of opto-electronic devices.
  • a wide variety of glass materials, material-dopants and waveguide structures are available and the present invention relates to a waveguide sensor which is particularly well suited for detecting and monitoring structural parameters caused by acoustic, mechanical, electrical and magnetic events (i.e. strain, vibration, resonance, acoustic emission, etc.).
  • the fibre optic modalmetric sensor has been proven to have good potential for vibrational analysis of structures and for machine condition monitoring applications.
  • Fibre optic sensors are very promising for these applications because of their dielectric properties, their fine size, their ability to be remotely located and, in the case of intrinsic sensors, rapid response times. They also have particular advantages in hazardous environments. In addition, they have several clear advantages over existing conventional sensing techniques such as bulk optical measurements, potentiometric electrodes, resistive foil gauges and piezo-electric transducers. Engineered structures are usually not monitored in real-time because of the difficulties in incorporating the sensors into the sensing environment and because of the limitations of the sensors. Optical sensors overcome these difficulties by virtue of their inherent properties. In addition, optical sensors and optical processing systems are extremely fast and do not suffer from electro-magnetic interference (EMI), unlike their electronic counter-parts.
  • EMI electro-magnetic interference
  • Multimode optical fibres suffer from optical signal fading and drift due to the random or chaotic nature of the light propagating along the fibre.
  • the optical fibre industry has overcome the inherent weaknesses of multimode fibres by the use of singlemode fibre systems, but these are difficult to handle, and utilise quite expensive components.
  • the claimed invention overcomes the inherent weaknesses of multimode fibre optic sensors, is easy to fabricate and costs relatively little to assemble.
  • Optical fibres were found to be very microphonic quite early in the development of fibre optic systems.
  • a source of coherent optical radiation is used to launch light into a multimode fibre and a photodetector monitors the transmitted output signal.
  • Loads, vibrations and acoustic signals acting on the multimode fibre causes a change in length, diameter, and refractive index of the fibre, resulting in phase and polarisation modulation of the individual modes supported in the fibre.
  • a number of methods for isolating either individual modes or the inner core region of a multimode fibre have been disclosed in the art.
  • One such method involves placing a singlemode fibre in close proximity to various locations on the end-face of a multimode fibre in order to selectively excite a single or limited number of modes in the multimode fibre and thus stabilise the fibre output.
  • a singlemode fibre in close proximity to various locations on the end-face of a multimode fibre in order to selectively excite a single or limited number of modes in the multimode fibre and thus stabilise the fibre output.
  • an external lens and spatial filter arrangement is used to isolate regions of the speckle pattern output of a multimode fibre such that a photodetector can measure the optical power in a given group of modes.
  • the laser diode pigtail was FC-connected to one port of a 633 nm singlemode, 3 dB (2X2) fibre optic coupler.
  • a 1300 nm singlemode fibre with 9/125 ⁇ core/cladding diameter and mirrored end-face was mechanically coupled to one of the sensor ports of the (2X2) coupler using a Dorran mechanical splice.
  • the other unused sensor port was fractured to minimise end reflections.
  • the remaining output port of the coupler was ST-connected to a photodiode.
  • the 1300 nm singlemode fibre was used as the multimode (approximately 4 modes) sensing fibre and the 633 nm, 3.7 ⁇ m core diameter fibre-lead of the coupler was used as a diaphragm as well as to deliver and return the optical signals to/from the sensing region.
  • the sensor lengths used were typically 70 mm in length.
  • Tapanes and Rossiter overcame some of the disadvantages of prior art techniques by using a mechanical splice to maintain alignment of the single and multi moded fibres by butting the fibres against one another and mechanically locking them in that position.
  • the precision V-groove of the mechanical splice and the identical overall diameters of the two fibres ensured that the core of the singlemode fibre was maintained in alignment with the central region of the multimode fibre end-face.
  • multimode fibre optic interferometer With very good response linearity, as well as reduced drift and signal fading.
  • the present invention provides a method for producing a sensor, including: providing a singlemode optical fibre formed from a waveguide material and having a fibre core; providing a multimode waveguide and having a waveguide core; fusion splicing the singlemode fibre and multimode waveguide so that centres of the cores of the singlemode fibre and multimode waveguide are aligned and remain fixed at the splice; and cleaving or polishing the multimode waveguide, after the fusion splicing, at a desired location spaced from the splice to localise the sensor.
  • a singlemode of electromagnetic radiation is launched into the singlemode fibre from a light source such as a laser and propagates along the singlemode fibre.
  • a light source such as a laser
  • the singlemode can branch out into multiplemodes within the multimode waveguide so that when the multimode fibre experiences a change due to the change in the environment it is monitoring, properties of the electromagnetic radiation in the multimode waveguide can be altered.
  • Light which has had its property altered in the multimode waveguide enters the singlemode fibre from the multimode waveguide for detection by the detecting device.
  • Cleaving or polishing of the multimode waveguide for application of a mirroring material to reflect radiation back to a detector or fusion splicing of a singlemode fibre for enabling light to pass from the multimode waveguide to the singlemode fibre and then to a detector without reflection enables size of the sensing portion, namely the multimode waveguide, to be controlled so that the sensing portion can be made considerably smaller than in prior art devices.
  • the singlemode and multimode fibres are prepared prior to fusion splicing by cleaving or polishing ends of the singlefibre and multimode waveguide to establish flat smooth surfaces at the ends of the singlemode fibre and multimode waveguide which are to be fusion spliced.
  • the cleaving or polishing at the desired location spaced from the fusion splice establishes a flat smooth surface at the desired location.
  • the flat smooth surface at the desired location is coated with a mirroring material to reflect radiation back through the multimode waveguide and then the singlemode fibre to a detecting device.
  • the cleaved or polished multimode waveguide is fusion spliced at a desired location to a singlemode fibre which in turn is coupled to a detecting device.
  • the singlemode fibre is coupled to a light source, and a detecting device.
  • a plurality of multimode waveguides and singlemode fibres are fusion spliced in end-to-end relationship to form a quasi-distributed sensor.
  • a plurality of singlemode fibres are fusion spliced to respective multimode waveguides and the plurality of singlemode fibres are connected to a coupler which in turn is connected to a further singlemode fibre to form a multiplexed sensor.
  • the multimode waveguide is a multimode fibre.
  • the invention may be said to reside in a method for producing a waveguide sensor, including, but not limited to, the steps of:
  • Preparing a singlemode and a multimode fibre by cleaving or polishing their ends so as to establish a flat, smooth surface. After taking necessary precautions to remove any contaminants from the cleaved or polished fibre end-faces, the fibres are placed end-to-end in a fusion splicing apparatus and fused together using the appropriate or desired fusion arch times and currents. The fusion splicing procedure may be repeated a number of times if necessary. Although it is not imperative, a preferred procedure for splicing the fibres involves setting the fusion splicing parameters such that the fibres are abruptly fused and not wholly fused in a tapered-like manner, such that a visible line separating the fibres is observable.
  • the smaller core of the singlemode fibre does not taper or merge with the larger core of the multimode fibre and, therefore, essentially retains the original diaphragm size.
  • the core and overall diameters of the fibres is not limited and translation stages and/or V-grooves may be used on the fusion splicing apparatus to centrally align the cores of the two fibres before the fusion splicing procedure. Different combinations of single and multi mode fibres may require a different or unique set of fusion splicing parameters.
  • Preparing or connectorising the free end of the singlemode fibre in any manner which facilitates attaching, connecting or coupling the singlemode-fibre-part of the sensor to the appropriate combination and arrangement of light source, coupler, photodiode and signal processing electronics.
  • the position of the cleave or polished surface establishes the localised length or sensing region of the sensor. Therefore, it is possible to produce localised sensing lengths less than 1 mm long.
  • a selected portion of the fibre, including the end-face of the multimode fibre, is mirrored with a suitable mirroring material (ie.. a metal or dielectric material).
  • a suitable mirroring material ie.. a metal or dielectric material.
  • a preferred method for mirroring the multimode fibre end-face involves placing the fibre in a vacuum system and the prepared fibre end-face is then coated with a metallic material such as Au, Ag, Al or Ti or a dielectric material such as Ti0 2 .
  • This coating can be prepared by using thermal evaporation, electron beam evaporation or sputtering. Other coating or mirroring materials and techniques may also be utilised.
  • the manufactured sensor and/or the exposed fusion spliced region may be protected by encapsulating or coating the desired region in a suitable material (ie. ultraviolet acrylate, epoxy, etc.) .
  • any suitable light source, coupler and photodetector may be used with the sensor.
  • the required optical properties of the light source are such that light may be launched into and propagated in the singlemode waveguide.
  • the light propagated in a singlemode fibre should remain singlemoded during the entire period of travel in the singlemode fibre. Once the light is launched into the multimode fibre from the singlemode fibre, several modes may be excited and the multimoded fibre will be sensitive to various parameters. Once the light is launched back into the singlemode fibre from the multimode fibre, only a single mode is supported and travels to the optical components of the system. Lead-in/lead-out fibre desensitisation and sensor localisation is achieved in this manner.
  • the singlemode fibre should be made sufficiently long to attenuate all cladding modes in order to improve the signal-to noise ratio.
  • the invention also provides a sensor including: a singlemode optical fibre formed from a waveguide material and having a fibre core; and a multimode waveguide and having a waveguide core, the multimode waveguide being fusion spliced to the singlemode optical fibre so that centres of the cores of the singlemode waveguide and multimode fibre are aligned and remain fixed at the splice; and wherein the multimode waveguide is cleaved or polished, after fusion splicing, at a desired location spaced from the fusion splice to localise the sensor.
  • the cleaving or polishing at the desired location spaced from the fusion splice establishes a flat smooth surface at the desired location.
  • the flat smooth surface at the desired location is coated with a mirror material to localise the sensor.
  • the cleaved or polished multimode waveguide is fusion spliced to a further singlemode fibre which is coupled to a detecting device.
  • the senor includes a light source and a detecting device.
  • the light source and detecting device are coupled to the singlemode fibre so that radiation, in use, is launched into the singlemode fibre and propagates along the singlemode fibre and also along the multimode waveguide wherein properties of the radiation are altered due to changes in a parameter which is to be monitored, and the radiation is reflected from the mirroring material back along the multimode waveguide and singlemode fibre for detection by the detecting device.
  • a plurality of multimode waveguides and singlemode fibres are fusion spliced end-to-end to provide multi-distributed sensors.
  • a plurality of singlemode fibres are fusion spliced to multimode waveguides and the singlemode fibres are coupled to a coupler which is in turn coupled to a further singlemode fibre to produce a multiplexed sensor.
  • the waveguide sensors according to this invention can be used in real-time to monitor engineering structures and fabricated items. Their small size enables them to be used in difficult-to-reach areas or embedded non intrusively in an object for in-situ monitoring.
  • the concept of incorporating the waveguide sensors into a patch body provides protection for the sensor and allows the patch body to be adhered to the surface of existing or completed structures.
  • Utilisation of properties and characteristics of the electromagnetic radiation propagating in the waveguide sensor also enables monitoring to take place in a non-destructive manner. Thus, the sensor is not necessarily fractured or destroyed in order to monitor the desired parameter.
  • the effective sensing length of the waveguide sensor can be varied for either point or integrated sensitivity.
  • Multi-point sensing can be achieved by quasi-distributed, distributed or multiplexed configurations.
  • the waveguide comprises at least one optical fibre and/or at least one optical fibre device.
  • the waveguide may merely comprise an optical fibre without any additional sensing elements.
  • the optical fibre can include sensing elements at its end or along its length and those sensing elements can comprise devices which will respond to a change in the desired parameter in the environment of application and influence the properties and characteristics of the electromagnetic radiation propagating in the waveguide to thereby provide an indication of the change in the parameter.
  • the waveguide or waveguides may be formed from any glass material, hard oxides, halides, crystals, sol-gel glass, polymeric material or may be any form of monolithic substrate. Electro-optic devices, acousto-optic devices, magneto-optic devices and/or integrated optical devices may also be utilised in the sensing system.
  • the fusion splicing takes place in a fusion splicer or by laser welding techniques, or by any other tecyhniquest to fuse the multimode waveguide and singlemode fibre.
  • Figure 1 is a view showing an embodiment of the invention illustrating fusion splicing and mirroring
  • Figure 2 is a more detailed view of the embodiment of figure 1;
  • Figure 3 is a view showing a further embodiment of the invention.
  • Figure 4 is a view showing a still further embodiment of the invention.
  • Figure 5 is a view showing yet a further embodiment of the invention.
  • a singlemode fibre 14 and a multimode fibre 18 are prepared by cleaning their ends so as to establish a flat, smooth surface. After taking necessary precautions to remove any contaminants from the cleaved fibre end-faces, the fibres are placed end-to-end in a fusion splicing apparatus and fused together at 17 using the appropriate or desired fusion arch times and currents. The multimode fibre 18 is then cleaved at any location after the fusion splice 17 so as to establish a flat, smooth surface. The position of the cleave or polished surface establishes the localised length or sensing region of the sensor 12.
  • a selected portion 15 of the fibre, including the end-face of the multimode fibre, is mirrored with a suitable mirroring material (ie., a metal or dielectric material) .
  • a fibre optic modalmetric sensor 10 according to the preferred embodiment comprises a multimode fibre 18 which is mirrored on its end-face 15 and fusion spliced 17 to a singlemode fibre patch cord 16.
  • the free end of the fibre optic modalmetric sensor 10 can be adhered to an engineering structure or manufactured article.
  • the singlemode fibre patch cord 16 is coupled to instrumentation 20 which includes a light source 22, coupler 26 and a detector and signal processing unit 24.
  • the patch cord 16 can be of any desired length, and indeed up to several kilometres, so the instrumentation 20 can be located remote from the multimode fibre 18 which forms the sensing element of the sensor 10.
  • the light source 22 provides light which is propagated along the singlemode fibre 14 in the singlemode fibre patch cord 16 and, which in the embodiment of figure 2, is reflected back along the optical fibre for detection by the unit 24.
  • the detecting unit provides light which is propagated along the singlemode fibre 14 in the singlemode fibre patch cord 16 and, which in the embodiment of figure 2, is reflected back along the optical fibre for detection by the unit 24.
  • the detecting unit can be of any desired length, and indeed up to several kilometres, so the instrumentation 20 can be located remote from the multimode fibre 18 which forms the sensing element of the sensor 10.
  • the light source 22 provides light which is propagated along the singlemode fibre 14 in the singlemode fibre patch cord 16 and, which in the embodiment of figure 2, is reflected back along the optical fibre for detection by the unit 24.
  • the detecting unit provides light which is propagated
  • the propagated light in the multimode fibre 18 which is eventually detected by the detector unit 24 has its properties and characteristics altered by a change in a desired parameter which is to be monitored.
  • the multimode fibre 18 and a small part of the singlemode fibre 14/patch cord 16 is located on a patch body (not shown) of host material to enable the sensor to be conveniently attached to a structure or the like.
  • a singlemode optical fibre patch cord 16 is coupled to the light source 22.
  • a multimode fibre 18 is then fusion spliced to the singlemode fibre 16 in the same manner as described with reference to figures 1 and 2.
  • the other end of the multimode fibre 18 is cleaved and prepared in the manner referred to above and fusion spliced to a further singlemode fibre 14.
  • the singlemode fibre 14 is fusion spliced to a multimode fibre 18 which is in turn is fusion spliced to a singlemode optical fibre patch cord 16 which is coupled to the detector and signal processing device 24.
  • a quasi-distributed sensor is produced which has sensing portions formed by the two multimode fibres 18 wherein the propagated electro ⁇ magnetic radiation is received by the detector 24 at the end of the optical path rather than by reflecting the radiation back from a mirrored end 15 as in the embodiment of figure 2.
  • the patch cord 16 including the singlemode fibre, connected to detector 24, could be replaced with a multimode fibre.
  • results may not be as good as the arrangement shown in figure 2 because of drift or interference in the multimode fibre which replaces the patch cord 16.
  • a quasi-distributed sensor arrangement 30 is illustrated. This arrangement is made possible by fusion splicing 17 insensitive singlemode fibre 14 sections between the sensitive multimode fibre 18 sections.
  • a multiplexed fibre optic modalmetric sensor system 40 is illustrated.
  • a (1XN) star coupler 42 joins the singlemode optical fibre patch cords 16 to one individual singlemode optical fibre patch cord 44. This type of configuration would be capable of mapping parameter fields.
  • the primary applications of the fibre optic modalmetric sensor according to the preferred embodiments of this invention is in structural integrity monitoring and machine condition monitoring.
  • the sensor could be used to monitor a wide variety of structures and machinery, for example: metal or composite material aerospace structures, satellites, marine vessels, submersible vessels, storage vessels, off-shore structures, pipelines, chemical storage containers, power transformers, power generators, hydro electric dams, gearboxes, motors, compressors, buildings, bridges, etc. Other parameters could also be monitored depending on the type of waveguide or sensor arrangement employe .
  • the sensors are capable of monitoring parameters in a reliable and non destructive manner.
  • the sensor waveguide does not rely on failure, fracture, breakage or any other form of permanent, irreversible change.
  • the sensing region was constructed by fusion splicing an optical fibre with 3.5/125 ⁇ m core/cladding diameter to an optical fibre with 9/125 ⁇ core/cladding diameter.
  • the multimode (larger core) fibre was cleaved approximately 10 mm from the fusion splice location and mirrored.
  • the singlemode fibre free-end was fusion spliced to one of the sensor ports of the (2X2) coupler.
  • the unused sensor port was fractured to minimise end reflections.
  • the remaining output port of the coupler was ST-connected to a ST-receptacled silicon photodiode. The sensor was then adhered to a steel cantilever beam with Ciba ⁇ eigry Araldite 24 hour epoxy.
  • ESG electrical strain gauge
  • the laser diode pigtail was fusion spliced to a 1300 nm singlemode, 3 dB (2X2) fibre optic coupler.
  • the sensing region was constructed by fusion splicing an optical fibre with 9/125 ⁇ m core/cladding diameter to an optical fibre with 50/125 ⁇ m core/cladding diameter.
  • the multimode (larger core) fibre was cleaved approximately 10 mm from the fusion splice location and mirrored.
  • the singlemode fibre free-end was fusion spliced to one of the sensor ports of the (2X2) coupler. The unused sensor port was fractured to minimise end reflections.
  • the remaining output port of the coupler was fusion spliced to a fibre pigtailed In ⁇ aAs photodiode.
  • the sensor was then adhered to a steel cantilever beam with Ciba Geigy Araldite 24 hour epoxy.
  • An electrical strain gauge (ESG) was also adhered to the beam using a cyanoacrylate adhesive, co-located with the fibre optic sensor, in order to compare results.
  • the steel beam was placed in a cantilever load frame and deflected. Dynamic experiments were performed by deflecting the beam tip and releasing.
  • the sensor signal output (vibration) and frequency response were compared with the ESG response. In each case the sensor response showed excellent correlation with the ESG response.
  • the lead-in/lead-out singlemode fibre showed no significant sensitivity to external perturbations, demonstrating good localisation of the sensor Example 3:
  • the laser diode pigtail was fusion spliced to a 1300 nm singlemode, 3 dB (2X2) fibre optic coupler.
  • the sensing region was constructed by fusion splicing an optical fibre with 9/125 ⁇ m core/cladding diameter to an optical fibre with 100/140 ⁇ m core/cladding diameter.
  • the multimode (larger core) fibre was cleaved approximately 10 mm from the fusion splice location and mirrored.
  • the singlemode fibre free-end was fusion spliced to one of the sensor ports of the (2X2) coupler. The unused sensor port was fractured to minimise end reflections.
  • the remaining output port of the coupler was fusion spliced to a fibre pigtailed InGaAs photodiode.
  • the sensor was then adhered to a steel cantilever beam with Ciba Geigy Araldite 24 hour epoxy.
  • An electrical strain gauge (ESG) was also adhered to the beam using a cyanoacrylate adhesive, co-located with the fibre optic sensor, in order to compare results.
  • the steel beam was placed in a cantilever load frame and deflected. Dynamic experiments were performed by deflecting the beam tip and releasing.
  • the sensor signal output (vibration) and frequency response via a Fast
  • the laser diode pigtail was fusion spliced to a 1300 nm singlemode, 3 dB (2X2) fibre optic coupler.
  • the sensing region was constructed by fusion splicing an optical fibre with 9/125 ⁇ m core/cladding diameter to an optical fibre with 100/140 ⁇ m core/cladding diameter.
  • the multimode (larger core) fibre was cleaved approximately 300 mm from the fusion splice location and mirrored.
  • the singlemode fibre free-end was FC-connectorised and connected to a FC receptacled sensor port of the (2X2) coupler.
  • the unused sensor port arm was fractured to minimise end reflections.
  • the remaining output port of the coupler was fusion spliced to a fibre pigtailed In ⁇ aAs photodiode.
  • the sensor was then encapsulated in a thin layer of Ciba Geigy Araldite 24 hour epoxy and embedded in a concrete beam.
  • the concrete beam was placed in a three-point bend apparatus and deflected.
  • the response of the sensor showed excellent agreement with the magnitude and frequency of the applied force.
  • the concrete beam was also impacted with a steel hammer and the sensor response showed the expected, high frequency response characteristics.
  • the lead-in/lead-out singlemode fibre showed no significant sensitivity to external perturbations, demonstrating good localisation of the sensor.
  • Optical devices made by the method of the invention and optical devices according to the invention are useful in a wide variety of applications and fields. Not inclusive, but indicatively, the following examples illustrate some applications in which the fibre optic modalmetric sensor may be used:
  • Aerospace structures operate on extremely tight tolerances and safety criteria. As a consequence, aerospace structures are often inspected at frequent intervals using labour intensive non-destructive techniques. Electrical strain gauges and piezo-electrics cannot be incorporated into the structure without detrimental effects and have a limited fatigue life. As a consequence, real-time structural integrity monitoring is rarely achieved in aerospace structures, except perhaps in sophisticated military research projects.
  • the fibre optic modalmetric sensor alternatively, can be adhered to the inner-surface of aerospace structures, thus not affecting the aerodynamics, and yet provide the following advantages over conventional sensors: they can perform quasi-static or dynamic measurements, have very high fatigue life, are corrosion resistant, are non-conductive, are capable of point or distributed sensing, can be configured to any shape or contour, and a single sensor is capable of monitoring several parameters simultaneously.
  • Fibre optic modalmetric sensors are not only resistant to corrosion, but they could possibly monitor the extent of corrosion of the structure. Lightning strikes would severely effect electrical or conductive devices, whereas optical sensors are generally not affected by this type of strike.
  • the fibre optic modalmetric sensors can be reliably adhered to critical areas of off-shore oil-rigs (ie. underwater support structures) and thus offers the opportunity to monitor the structural integrity in real-time. On-board the oil-rig, fibre optic modalmetric sensors could continuously monitor structural vibrations.
  • EMI electro-magnetic interference
  • Insulation degradation of large power equipment is one of the major concerns of electricity supply authorities. Forced outage of a large generator or transformer due to insulation breakdown can cost millions of dollars in repair and outage costs. The potential for generator and transformer outage is ever increasing as a large proportion of the capital equipment in the Australian and international electrical industry is nearing its expected lifetime. Replacement and refurbishment of these major components has significantly slowed down because of economic restraints and many are now operating beyond their expected operational lifetime. Therefore, it is important to closely monitor the insulation condition of these components and determine the remnant life of the electrical generating plant. Partial discharge (PD) measurements have been one of the most effective diagnostic tools for monitoring the insulation condition of high voltage equipment.
  • PD Partial discharge
  • the fibre optic modalmetric sensor offers a new technique for PD measurements in the power industry by monitoring minute, high frequency acoustic emission signals in the structure. Machine condition monitoring can be performed simultaneously with the fibre optic modalmetric sensor by low-pass filtering the signal and performing frequency analysis of the structural resonances.
  • the fibre optic modalmetric sensor offers several advantages over other PD detectors currently under development around the world, these include: less complex, small size, ease of use, safer for the high voltage equipment insulation, more reliable for noise discrimination (immunity to EMI) and cost effective.
  • Undersea pipelines are generally not monitored at all due to the lack of any reliable and durable sensing techniques. If something goes wrong with a pipeline (ie., cracking, corrosion, etc.) it is usually realised when the output flow is affected. No information is available as to the type and location of the fault. Obviously, this is an inefficient and potentially costly situation. Not only has the flow of goods stopped, but the pipeline has to be pulled up or divers/robots need to go down to have a look for the fault. Undersea pipelines are in a very harsh and corrosive environment. In addition, their lengths can vary from a few meters to several hundred kilometres in length.
  • load cells which are configuration of resistive strain devices.
  • the cells have a characteristic narrow load range within which accuracy and sensitivities are within tolerance.
  • the narrowness of this operating range derives from the non-linearity of the electrical resistance response to strain, a feature which the fibre optic modalmetric sensor overcomes.
  • load cells constructed with fibre optic modalmetric sensor components should be more sensitive at most loads but cover a much broader range off loads. This would result in the current series of load cells being replaced by a single broad-range fibre optical modalmetric sensor cell.
  • An added advantage would be the zero sensitivity of the fibre optic modalmetric sensor cells to electrical noise and harmonic responses to set frequencies of loading.
  • Structural integrity monitoring applications in general.
  • Machine condition monitoring applications in general.
  • Optical signal processing, conditioning, stabilisation and optimisation applications in general.
  • the fibre optic modalmetric sensor may be used in most applications where conventional sensors such as electrical strain gauges, accelerometers, thermocouples, make-break circuits and piezo-electric sensors are employed or might be employed if they were less limited. Not inclusive, but indicatively, the following examples illustrate some users of the fibre optic modalmetric sensor:
  • the ibre optic modalmetric sensor overcomes the inherent weaknesses, is easy to fabricate and costs relatively little to assemble.
  • Such a sensing system would offer low cost and increased safety advantages over existing technologies and has the potential for short to long term installation monitoring in plant, ecological (i.e., undersea) and other environments.
  • Many applications of the fibre optic modalmetric sensor are possible because of it's sensitivity, simplicity and cost effectiveness.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Optical Transform (AREA)
  • Mechanical Coupling Of Light Guides (AREA)

Abstract

La présente invention concerne un capteur optique et un procédé de fabrication d'un capteur optique dans lequel une fibre monomode (14) est aboutée par fusion à une fibre multimode (18). A l'autre extrémité de la jonction (17), la fibre multimode est fendue ou polie à l'emplacement prévu pour recevoir le détecteur. L'extrémité (15) de la fibre multimode peut alors comporter un miroir réfléchissant les rayons par la fibre multimode de façon à les faire repasser dans la fibre monomode pour détection par un capteur (24). Une autre réalisation consiste à coupler une source lumineuse (22) à la fibre monomode, une autre fibre monomode étant raccordée à la fibre multimode à l'emplacement prévu à la fibre multimode par une jonction par fusion. Il est ainsi possible de raccorder à l'autre fibre monomode un capteur (24) détectant les rayons passant par la fibre multimode et dont les propriétés sont modifiées dans la fibre multimode.
PCT/AU1995/000568 1994-09-13 1995-09-01 Capteurs optiques et procede de production de capteurs a detection de mode pour fibres optiques WO1996008695A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
GB9704123A GB2307551B (en) 1994-09-13 1995-09-01 Optical sensors and method for producing fibre optic modalmetric sensors
CA002198593A CA2198593C (fr) 1994-09-13 1995-09-01 Capteurs optiques et procede de production de capteurs a detection de mode pour fibres optiques
AU33768/95A AU688113B2 (en) 1994-09-13 1995-09-01 Optical sensors and method for producing fibre optic modalmetric sensors

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPM8043 1994-09-13
AUPM8043A AUPM804394A0 (en) 1994-09-13 1994-09-13 Method for producing fibre optic modalmetric sensors and applications thereof

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WO1996008695A1 true WO1996008695A1 (fr) 1996-03-21

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CA (1) CA2198593C (fr)
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Cited By (23)

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Publication number Priority date Publication date Assignee Title
WO1998059219A3 (fr) * 1997-06-20 1999-04-29 Secr Defence Detecteur de courbure de fibre optique
US6776543B1 (en) 2003-02-04 2004-08-17 Hewlett-Packard Development Company, L.P. Fiber optic print media thickness sensor and method
US7092586B2 (en) 2003-07-18 2006-08-15 Network Integrity Systems Inc. Intrusion detection system for use on an optical fiber using a translator of transmitted data for optimum monitoring conditions
US7173690B2 (en) 2003-07-03 2007-02-06 Senstar-Stellar Corporation Method and apparatus using polarisation optical time domain reflectometry for security applications
EP1151279A4 (fr) * 1998-12-18 2007-12-05 Future Fibre Tech Pty Ltd Appareil et procede destines a surveiller une structure a l'aide d'un procede de propagation opposee de signaux pour localiser des evenements
US7376293B2 (en) 2003-07-18 2008-05-20 Network Intergrity Systems Inc. Remote location of active section of fiber in a multimode intrusion detection system
US7403674B2 (en) 2003-07-18 2008-07-22 Network Integrity Systems Inc. Intrusion detection system for a multimode optical fiber using a bulk optical wavelength division multiplexer for maintaining modal power distribution
US7403675B2 (en) 2003-07-18 2008-07-22 Network Integrity Systems Inc. Method of high order mode excitation for multimode intrusion detection
CN101965367A (zh) * 2008-03-11 2011-02-02 未来纤维技术有限公司 模式度量型光纤传感器
WO2011044619A1 (fr) * 2009-10-14 2011-04-21 Future Fibre Technologies Pty Ltd Capteur à fibre modale métrique
EP2385357A1 (fr) * 2010-05-06 2011-11-09 Siemens Aktiengesellschaft Capteur de vibrations à fibre optique
CN103852093A (zh) * 2013-12-19 2014-06-11 哈尔滨工业大学（威海） 一种基于模式干涉反射结构的光纤激光传感系统
CN107490429A (zh) * 2017-07-21 2017-12-19 国网上海市电力公司 一种地埋电缆防误开挖预警装置
CN107525579A (zh) * 2017-07-21 2017-12-29 国网上海市电力公司 一种基于光纤双模式耦合的多防区振动探测装置
CN110243456A (zh) * 2019-07-23 2019-09-17 国网上海市电力公司 一种基于光纤双模式耦合的多防区振动探测装置
CN111076751A (zh) * 2019-12-30 2020-04-28 苏州德睿电力科技有限公司 一种基于ald镀膜的高灵敏度光波导传感器及其制备方法
CN112816996A (zh) * 2021-01-29 2021-05-18 太原理工大学 利用光谐振腔实现多模光纤故障位置的检测装置及方法
CN113589439A (zh) * 2021-07-29 2021-11-02 西南交通大学 一种基于双芯光纤的纤维集成Sagnac全反镜、方法和光系统
US11585692B2 (en) * 2019-10-24 2023-02-21 Palo Alto Research Center Incorporated Fiber optic sensing system for grid-based assets
US11719559B2 (en) 2019-10-24 2023-08-08 Palo Alto Research Center Incorporated Fiber optic sensing system for grid-based assets
WO2023196795A3 (fr) * 2022-04-04 2023-11-23 University Of Pittsburgh-Of The Commonwealth System Of Higher Education Système de surveillance basé sur des capteurs interférométriques multimodes multiplexés
CN119068615A (zh) * 2024-11-07 2024-12-03 南通围界盾智能科技有限公司 基于光纤传感的隧道电缆入侵探测系统
EP4248181A4 (fr) * 2020-11-17 2025-01-01 Teldor Cables & Systems Ltd. Détection de vibration distribuée par fibres optiques

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* Cited by examiner, † Cited by third party
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CN107247037B (zh) * 2017-07-28 2023-06-02 中国工程物理研究院激光聚变研究中心 基于单模-多模-无芯光纤结构的分子态有机污染物监测传感器

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4292023A (en) * 1979-08-01 1981-09-29 Curtiss-Wright Corporation Fluidized bed combustor and removable windbox and tube assembly therefor
US4628831A (en) * 1982-01-20 1986-12-16 Charbonnages De France Hearth and process for fluidized-bed treatment of a fuel
CH659876A5 (de) * 1983-05-10 1987-02-27 Sulzer Ag Wirbelbettfeuerung.
DE3623177A1 (de) * 1986-06-23 1988-01-07 Ruhrkohle Waerme Gmbh Brennkammer fuer atmosphaerische stationaere wirbelschichtfeuerung

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5008545A (en) * 1989-10-23 1991-04-16 Tektronix, Inc. High resolution optical fault locator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4292023A (en) * 1979-08-01 1981-09-29 Curtiss-Wright Corporation Fluidized bed combustor and removable windbox and tube assembly therefor
US4628831A (en) * 1982-01-20 1986-12-16 Charbonnages De France Hearth and process for fluidized-bed treatment of a fuel
CH659876A5 (de) * 1983-05-10 1987-02-27 Sulzer Ag Wirbelbettfeuerung.
DE3623177A1 (de) * 1986-06-23 1988-01-07 Ruhrkohle Waerme Gmbh Brennkammer fuer atmosphaerische stationaere wirbelschichtfeuerung

Cited By (34)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2341445A (en) * 1997-06-20 2000-03-15 Secr Defence Optical fibre bend sensor
GB2341445B (en) * 1997-06-20 2002-01-02 Secr Defence Optical fibre bend sensor
EP1134556A3 (fr) * 1997-06-20 2002-04-10 QinetiQ Limited Detecteur de courbure de fibre optique
US6389187B1 (en) 1997-06-20 2002-05-14 Qinetiq Limited Optical fiber bend sensor
US6621956B2 (en) 1997-06-20 2003-09-16 Qinetiq Limited Optical fibre bend sensor
WO1998059219A3 (fr) * 1997-06-20 1999-04-29 Secr Defence Detecteur de courbure de fibre optique
EP1151279A4 (fr) * 1998-12-18 2007-12-05 Future Fibre Tech Pty Ltd Appareil et procede destines a surveiller une structure a l'aide d'un procede de propagation opposee de signaux pour localiser des evenements
US6776543B1 (en) 2003-02-04 2004-08-17 Hewlett-Packard Development Company, L.P. Fiber optic print media thickness sensor and method
US7173690B2 (en) 2003-07-03 2007-02-06 Senstar-Stellar Corporation Method and apparatus using polarisation optical time domain reflectometry for security applications
US7120324B2 (en) 2003-07-18 2006-10-10 Network Integrity Systems Inc. Intrusion detection system for use on an optical fiber using a translator of transmitted data for optimum monitoring conditions
US7376293B2 (en) 2003-07-18 2008-05-20 Network Intergrity Systems Inc. Remote location of active section of fiber in a multimode intrusion detection system
US7403674B2 (en) 2003-07-18 2008-07-22 Network Integrity Systems Inc. Intrusion detection system for a multimode optical fiber using a bulk optical wavelength division multiplexer for maintaining modal power distribution
US7403675B2 (en) 2003-07-18 2008-07-22 Network Integrity Systems Inc. Method of high order mode excitation for multimode intrusion detection
US7092586B2 (en) 2003-07-18 2006-08-15 Network Integrity Systems Inc. Intrusion detection system for use on an optical fiber using a translator of transmitted data for optimum monitoring conditions
CN101965367A (zh) * 2008-03-11 2011-02-02 未来纤维技术有限公司 模式度量型光纤传感器
US8792754B2 (en) 2009-10-14 2014-07-29 Future Fibre Technologies Pty Ltd Modalmetric fibre sensor
WO2011044619A1 (fr) * 2009-10-14 2011-04-21 Future Fibre Technologies Pty Ltd Capteur à fibre modale métrique
AU2010306071B2 (en) * 2009-10-14 2015-08-27 Future Fibre Technologies Pty Ltd Modalmetric fibre sensor
EP2385357A1 (fr) * 2010-05-06 2011-11-09 Siemens Aktiengesellschaft Capteur de vibrations à fibre optique
US8559772B2 (en) 2010-05-06 2013-10-15 Siemens Aktiengesellschaft Fiber-optic vibration sensor
CN103852093A (zh) * 2013-12-19 2014-06-11 哈尔滨工业大学（威海） 一种基于模式干涉反射结构的光纤激光传感系统
CN107490429A (zh) * 2017-07-21 2017-12-19 国网上海市电力公司 一种地埋电缆防误开挖预警装置
CN107525579A (zh) * 2017-07-21 2017-12-29 国网上海市电力公司 一种基于光纤双模式耦合的多防区振动探测装置
CN110243456A (zh) * 2019-07-23 2019-09-17 国网上海市电力公司 一种基于光纤双模式耦合的多防区振动探测装置
US11585692B2 (en) * 2019-10-24 2023-02-21 Palo Alto Research Center Incorporated Fiber optic sensing system for grid-based assets
US11719559B2 (en) 2019-10-24 2023-08-08 Palo Alto Research Center Incorporated Fiber optic sensing system for grid-based assets
CN111076751A (zh) * 2019-12-30 2020-04-28 苏州德睿电力科技有限公司 一种基于ald镀膜的高灵敏度光波导传感器及其制备方法
EP4248181A4 (fr) * 2020-11-17 2025-01-01 Teldor Cables & Systems Ltd. Détection de vibration distribuée par fibres optiques
CN112816996A (zh) * 2021-01-29 2021-05-18 太原理工大学 利用光谐振腔实现多模光纤故障位置的检测装置及方法
CN112816996B (zh) * 2021-01-29 2023-09-15 太原理工大学 利用光谐振腔实现多模光纤故障位置的检测装置及方法
CN113589439A (zh) * 2021-07-29 2021-11-02 西南交通大学 一种基于双芯光纤的纤维集成Sagnac全反镜、方法和光系统
CN113589439B (zh) * 2021-07-29 2022-05-13 西南交通大学 一种基于双芯光纤的纤维集成Sagnac全反镜、方法和光系统
WO2023196795A3 (fr) * 2022-04-04 2023-11-23 University Of Pittsburgh-Of The Commonwealth System Of Higher Education Système de surveillance basé sur des capteurs interférométriques multimodes multiplexés
CN119068615A (zh) * 2024-11-07 2024-12-03 南通围界盾智能科技有限公司 基于光纤传感的隧道电缆入侵探测系统

Also Published As

Publication number Publication date
AUPM804394A0 (en) 1994-10-06
GB9704123D0 (en) 1997-04-16
GB2307551A (en) 1997-05-28
GB2307551B (en) 1999-08-11
CA2198593C (fr) 2005-01-11
CA2198593A1 (fr) 1996-03-21

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