WO2005083379A1 - Capteur a fibre optique a plusieurs bras - Google Patents

Capteur a fibre optique a plusieurs bras Download PDF

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Publication number
WO2005083379A1
WO2005083379A1 PCT/SG2004/000045 SG2004000045W WO2005083379A1 WO 2005083379 A1 WO2005083379 A1 WO 2005083379A1 SG 2004000045 W SG2004000045 W SG 2004000045W WO 2005083379 A1 WO2005083379 A1 WO 2005083379A1
Authority
WO
WIPO (PCT)
Prior art keywords
sensor
fiber optic
layers
arm
bragg grating
Prior art date
Application number
PCT/SG2004/000045
Other languages
English (en)
Inventor
Swee Chuan Tjin
Original Assignee
Sif Universal Private Limited
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 Sif Universal Private Limited filed Critical Sif Universal Private Limited
Priority to PCT/SG2004/000045 priority Critical patent/WO2005083379A1/fr
Publication of WO2005083379A1 publication Critical patent/WO2005083379A1/fr

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/18—Diffraction gratings
    • G02B5/1814—Diffraction gratings structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings
    • 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
    • G01K11/3206—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 at discrete locations in the fibre, e.g. using Bragg scattering
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
    • G01K3/00—Thermometers giving results other than momentary value of temperature
    • G01K3/08—Thermometers giving results other than momentary value of temperature giving differences of values; giving differentiated values
    • G01K3/14—Thermometers giving results other than momentary value of temperature giving differences of values; giving differentiated values in respect of space
    • 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
    • G01L1/246—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 using integrated gratings, e.g. Bragg gratings
    • 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
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
    • G02B6/02076—Refractive index modulation gratings, e.g. Bragg gratings
    • G02B6/02171—Refractive index modulation gratings, e.g. Bragg gratings characterised by means for compensating environmentally induced changes
    • G02B6/02176—Refractive index modulation gratings, e.g. Bragg gratings characterised by means for compensating environmentally induced changes due to temperature fluctuations
    • G02B6/0218—Refractive index modulation gratings, e.g. Bragg gratings characterised by means for compensating environmentally induced changes due to temperature fluctuations using mounting means, e.g. by using a combination of materials having different thermal expansion coefficients

Definitions

  • This invention relates to a multi-arm fiber optic sensor and refers particularly, though not exclusively, to a multi-arm fiber optic sensor where each arm has a Bragg grating.
  • the invention also relates to such a sensor used as a force sensor able to compensate for temperature variation, and such a sensor for obtaining temperature variations.
  • the earlier application discloses an optic force sensor that uses a single arm of a fiber optic with a Bragg grating.
  • a fiber optic force sensor using a Bragg grating that is able to compensate for temperature variation would be of great advantage.
  • Such a sensor able to obtain temperature variations would also be of considerable advantage.
  • a fiber optic sensor comprising: (a) a fiber optic having a plurality of operatively connected arms, each arm having a Bragg grating; (b) the fiber optic being embedded between a plurality of embedding layers; (c) the embedding layers comprising an upper portion with at least one upper layer and a lower portion with at least one lower layer.
  • the fiber optic sensor may be used as a force sensor able to compensate for temperature variation; and preferably is able to read temperature, or expansion/ contraction due to temperature.
  • a fiber optic force sensor comprising:
  • the fiber optic being embedded between a plurality of embedding layers;
  • the embedding layers comprising an upper portion with at least one upper layer and a lower portion with at least one lower layer;
  • each of the plurality of arms is parallel.
  • the fiber optic may comprise a first arm operatively connected to a second arm by an arcuate portion, the first arm having a first Bragg grating and the second arm having a second Bragg grating.
  • the first Bragg grating may be axially aligned with the second Bragg grating.
  • the first Bragg grating and the second Bragg grating are in different planes, with there being at least one embedding layer between them.
  • the embedding material may be one or more of: metal, polymer, ceramic, carbon fibre composite, and so forth.
  • the embedded layers in contact with each Bragg grating have fibers with their axis aligned with an optical axis of the arm of the fiber optic on which the Bragg grating is written. More preferably, all other layers have fibers oriented either cross-ply or parallel-ply.
  • the upper portion may comprise a plurality of upper layers, each of the plurality of upper layers being identical and parallel.
  • the plurality of upper layers may be oriented in a cross-ply arrangement and/or parallel-ply arrangement.
  • the lower portion may comprise a plurality of lower layers, each of the plurality of lower layers being identical and parallel.
  • the plurality of lower layers may be oriented in a cross-ply arrangement and/or parallel-ply arrangement.
  • the number of upper layers may be the same as the number of lower layers. Alternatively, the number of upper layers may be different to the number of lower layers.
  • Figure 1 is an exploded perspective view of a first, preferred embodiment
  • Figure 2 is a perspective view of a second, preferred embodiment
  • Figure 3 is a perspective view of the embodiment of Figure 1 ;
  • Figure 4 is a graph illustrating the temperature spectrum for the embodiments of
  • Figure 1 shows an exploded perspective view of a first embodiment of a sensor according to the present invention
  • Figure 3 shows that same embodiment as assembled.
  • an optical fiber 203 with a fiber Bragg grating generally referred as 204 the optical fiber being embedded between embedding layers generally shown as 202.
  • the Bragg wavelength depends on the temperature of the Bragg grating 204.
  • the optical fiber 203 is formed as a loop, with there being a first arm 205 and a second arm 206, the two arms 205, 206 being joined by an arcuate portion 207.
  • First arm 205 has a first longitudinal axis 208 and second arm has a second longitudinal axis 209.
  • axes 208, 209 are parallel, and spaced apart. In that way the arms 205, 206 are parallel to each other.
  • Each arm 205, 206 has a Bragg grating 204.
  • the Bragg gratings 204 are axially aligned - they are at a location on each arm 205, 206 the same distance from arcuate portion 207.
  • Each arm 205, 206 as well as their Bragg gratings 204, are in different planes with there being at least one embedding layer 201 between them.
  • the embedding layer(s) 201 may be of any suitable material such as for example, metal, ceramic, polymer, carbon fiber composite, carbon fiber prepregs, and so forth.
  • the fibers are preferably all aligned.
  • the axes of the fibers are preferably parallel to the optical axis of the arm 205, 206 on which the Bragg grating 204 is written. All other layers may be cross-ply or parallel-ply.
  • the layers 202 have an upper portion 210 and lower portion 211.
  • the upper portion 210 has at least one layer (as illustrated) but preferably has a plurality of layers.
  • the lower portion 211 preferably has at least one layer (as illustrated) but preferably has a plurality of layers.
  • the layers of the upper portion 210 and lower portion 211 may be cross-ply or parallel-ply.
  • the number of layers in lower portion 211 may be the same as the number of layers in the upper portion 210. Alternatively, the number of layers in the lower portion 211 may be different to the number of layers in the upper portion 210. It is preferred for the layers in upper portion 210 to be the same as the layers in the lower portion 211.
  • the orientation of the layers in the upper portion 210 is preferably the same as the orientation of the layers in the lower portion 211. If the layers in one of the portions 210, 211 are in a cross-ply arrangement, the layers in the other portion are preferably also in a cross-ply arrangement. Alternatively, the layers in one of the portions 210, 211 may be cross-ply, and the layers in the other portion may be parallel-ply.
  • the arms 205 and 206 are aligned such that their axes 208, 209 are in planes generally parallel with the planes of upper portion 210 and lower portion 211 and are vertically aligned.
  • Figure 2 shows a variation.
  • the axes 208, 209 are aligned at an angle to the horizontal and the vertical. The angle may be in the range 1° to 179°.
  • the optical fiber 203 may be located in or adjacent to the neutral layer between portions 210, 211, the location being as required or desired. Alternatively, the optical fiber may be remote from the neutral layer.
  • a fiber Bragg grating will reflect light that has a wavelength ⁇ t corresponding to twice its period ⁇ , multiplied by the effective refractive index of the fiber n ⁇ ff that the propagating mode sees.
  • ⁇ 2 ⁇ n ⁇ ff
  • the Bragg condition This is called the Bragg condition, and ⁇ is called the Bragg wavelength.
  • Light at other wavelengths will be transmitted without significant attenuation.
  • the grating operates as a narrow-band wavelength notch filter.
  • any force or pressure or strain or stress or thermal energy applied to the fiber Bragg grating results in a shift in the Bragg wavelength t of the sensor, which can be detected in either the reflected signal or spectrum l r or in the transmitted signal or spectrum l . Since the measured information is encoded directly into wavelength, which is in absolute power, the resultant data acquired does not depend directly on the total light intensity, on losses in connectors or on the source power level. For this reason, a thermal and/or force sensor using a fiber Bragg grating is particularly insensitive to exterior deteriorations such as variations in the light intensity or light losses. Therefore, the thermal and/or force sensor according to the present invention is particularly reliable and robust.
  • the effect of the temperature effect ⁇ T will depend on whether Ti is greater or less than T 2 .
  • FIG. 6 Another advantage of having two arms 205, 206 for optical fibre 203, and each arm having a Bragg grating 204, is that the sensor is able to respond to forces in two directions. This is shown in Figures 6 to 9.
  • the force is applied in one direction - either as a compressive force from above, or as a tensile force from below.
  • the force differential ⁇ F between arms 205 and 206 can be detected.
  • the force is applied in the opposite direction - either as a compressive force from below, or as a tensile force from above.
  • the force differential ⁇ F can be detected.
  • the exerted force results in a variation of the predetermined optical transmittance and reflectance of the Bragg grating 204.
  • a force sensor having the fiber Bragg grating 204 can be used in particular to measure a force applied perpendicularly to the fiber optical axis 208, 209 and perpendicular to the plane of the layer portions 210, 211 and is, therefore, capable of measuring a pressure exerted upon either one of the layer portions 210, 211.
  • This pressure sensor can nevertheless be used also to measure a stress or strain exerted in the plane of the layer portions 210, 211 and, in particular in the longitudinal direction of the optical fiber 203. Accordingly, this sensor can also be used as strain sensor.
  • a force sensor having a fiber Bragg grating embedded between the lower portion 211 and the upper portion 210 according to the invention represents an indirect sensing device.
  • the indirect sensing device and technique of the invention using an embedded fiber Bragg grating offers several advantages.
  • the embedded fiber Bragg grating extends, both in case of pressure and of a strain sensor according to the invention, extends the range of forces that can be applied to the fiber Bragg grating with no permanent damage to the fiber Bragg grating.
  • the response of the embedded fiber shows improved stability with respect to time as compared to that of a bare fiber Bragg grating used in direct sensing techniques. Such stability is observed when a static force is applied to both the bare and embedded fiber Bragg grating and the drift in the axial strain is observed over a period of time.
  • the fiber Bragg grating sensor with two fiber optic arms 205, 206 can be used as a force sensor not affected by temperature variation.
  • the sensor is able to read temperature, or expansion/contraction due to temperature.
  • Such a sensor is sometimes referred to as an "athermal" sensor.
  • the optical fiber 203 may have a diameter that is comparable to a thickness of each layer, although this is not necessary.
  • the optical fiber 203 can be acrylate-coated, polyimide-coated or uncoated, which is selected according to which materials are contained in the layers.
  • the coating if such is provided preferably has a thickness of typically 10 microns.
  • each layer is made of a composite material comprising a polymer material and elongated carbon fibers being arranged in parallel within each layer.
  • Each layer may be thermally and/or electrically insulating.
  • each layer can comprise glass fibers instead of or in addition to the carbon fibers.
  • an epoxy resin material or a polyester resin material is used in the layers.
  • the optical fiber 203 has a diameter that is considerably larger than a diameter of the elongated fibers. This provides a smoother bending of the optical fiber 203 embedded between the lower portion 211 and the upper portion 210.
  • the thickness and number of the layers of portions 210, 211 should be selected such that the sensor has a predetermined sensitivity to the external force, F.
  • F external force
  • a fiber optic with two arms 205, 206 has been described the arms 205, 206 being joined by an arcuate portion 207, and each arm 205, 206 having a Bragg grating 204, it will be realized that three or more (e.g. three, four, five, six and so forth) arms could be provided, each with a Bragg grating 204.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Transform (AREA)
  • Measuring Temperature Or Quantity Of Heat (AREA)

Abstract

La présente invention concerne un capteur à fibre optique comprenant une fibre optique (203) comportant deux bras parallèles (205, 206) fonctionnellement connectés, chaque bras étant pourvu d'un réseau de Bragg (204). La fibre optique est noyée entre une pluralité de couches d'enrobage. Les couches d'enrobage comprennent une partie supérieure (210) comportant au moins une couche supérieure et une partie inférieure comportant au moins une couche inférieure. Les bras (205, 206) sont fonctionnellement reliés par une partie cintrée (207). Au moins une couche d'enrobage (201) est prévue entre le premier bras (205) et le deuxième bras (206). Le capteur n'est pas sensible à la température et peut lire la température ou la contraction/dilatation due à la température.
PCT/SG2004/000045 2004-02-26 2004-02-26 Capteur a fibre optique a plusieurs bras WO2005083379A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/SG2004/000045 WO2005083379A1 (fr) 2004-02-26 2004-02-26 Capteur a fibre optique a plusieurs bras

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/SG2004/000045 WO2005083379A1 (fr) 2004-02-26 2004-02-26 Capteur a fibre optique a plusieurs bras

Publications (1)

Publication Number Publication Date
WO2005083379A1 true WO2005083379A1 (fr) 2005-09-09

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006107278A1 (fr) * 2005-04-05 2006-10-12 Agency For Science, Technology And Research Detecteur de reseau de bragg dans une fibre
WO2009111827A1 (fr) * 2008-03-11 2009-09-17 Commonwealth Scientific And Industrial Research Organisation Dispositif optique
CN103674358A (zh) * 2013-11-25 2014-03-26 中国航空工业集团公司北京长城计量测试技术研究所 一种膜片式光纤f-p腔压力传感器温度补偿方法
DE102014200955A1 (de) * 2014-01-21 2015-07-23 Bayerische Motoren Werke Aktiengesellschaft Erfassung von lokalen Temperaturen eines in einem Presswerkzeug angeordneten Bauteils aus einem Faserverbundwerkstoff
JP2016013667A (ja) * 2014-07-03 2016-01-28 三菱電機株式会社 ハニカムサンドイッチ構造体およびその製造方法
CN105371880A (zh) * 2015-12-21 2016-03-02 山东大学 用于注塑制品检测的光纤光栅传感器嵌件及其制造方法
CN105606275A (zh) * 2015-12-21 2016-05-25 山东大学 一种隔膜滤板的芯板在线监测系统及方法
CN107631739A (zh) * 2017-09-07 2018-01-26 西安交通大学 光纤光栅振动/应力复合传感器
CN110095201A (zh) * 2019-04-10 2019-08-06 三峡大学 实时监测混凝土坝空间温度分布的分布式光纤测温系统及其方法
US11167509B2 (en) * 2016-02-02 2021-11-09 Mitsubishi Heavy Industries, Ltd. Composite-material molding apparatus and composite-material molding method
US20220341729A1 (en) * 2021-04-21 2022-10-27 Saudi Arabian Oil Company Fiber optic sensor network for subsurface impact protection system

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5399854A (en) * 1994-03-08 1995-03-21 United Technologies Corporation Embedded optical sensor capable of strain and temperature measurement using a single diffraction grating
US5646400A (en) * 1995-07-14 1997-07-08 The United States Of America As Represented By The Secretary Of The Navy Corrosion detecting and monitoring method and apparatus
US5770155A (en) * 1995-11-21 1998-06-23 United Technologies Corporation Composite structure resin cure monitoring apparatus using an optical fiber grating sensor
EP1148324A2 (fr) * 2000-04-17 2001-10-24 NTT Advanced Technology Corporation Capteur à fibre optique du type patch
WO2002046712A1 (fr) * 2000-12-07 2002-06-13 Nanyang Technological University Detecteur de force pour fibre optique

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5399854A (en) * 1994-03-08 1995-03-21 United Technologies Corporation Embedded optical sensor capable of strain and temperature measurement using a single diffraction grating
US5646400A (en) * 1995-07-14 1997-07-08 The United States Of America As Represented By The Secretary Of The Navy Corrosion detecting and monitoring method and apparatus
US5770155A (en) * 1995-11-21 1998-06-23 United Technologies Corporation Composite structure resin cure monitoring apparatus using an optical fiber grating sensor
EP1148324A2 (fr) * 2000-04-17 2001-10-24 NTT Advanced Technology Corporation Capteur à fibre optique du type patch
WO2002046712A1 (fr) * 2000-12-07 2002-06-13 Nanyang Technological University Detecteur de force pour fibre optique

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2006107278A1 (fr) * 2005-04-05 2006-10-12 Agency For Science, Technology And Research Detecteur de reseau de bragg dans une fibre
US7702190B2 (en) 2005-04-05 2010-04-20 Agency For Science, Technology And Research Fiber Bragg grating sensor
WO2009111827A1 (fr) * 2008-03-11 2009-09-17 Commonwealth Scientific And Industrial Research Organisation Dispositif optique
US8724935B2 (en) 2008-03-11 2014-05-13 Commonwealth Scientific And Industrial Research Organisation Optical device
CN103674358A (zh) * 2013-11-25 2014-03-26 中国航空工业集团公司北京长城计量测试技术研究所 一种膜片式光纤f-p腔压力传感器温度补偿方法
CN103674358B (zh) * 2013-11-25 2015-06-17 中国航空工业集团公司北京长城计量测试技术研究所 一种膜片式光纤f-p腔压力传感器温度补偿方法
DE102014200955A1 (de) * 2014-01-21 2015-07-23 Bayerische Motoren Werke Aktiengesellschaft Erfassung von lokalen Temperaturen eines in einem Presswerkzeug angeordneten Bauteils aus einem Faserverbundwerkstoff
JP2016013667A (ja) * 2014-07-03 2016-01-28 三菱電機株式会社 ハニカムサンドイッチ構造体およびその製造方法
CN105371880A (zh) * 2015-12-21 2016-03-02 山东大学 用于注塑制品检测的光纤光栅传感器嵌件及其制造方法
CN105606275A (zh) * 2015-12-21 2016-05-25 山东大学 一种隔膜滤板的芯板在线监测系统及方法
US11167509B2 (en) * 2016-02-02 2021-11-09 Mitsubishi Heavy Industries, Ltd. Composite-material molding apparatus and composite-material molding method
CN107631739A (zh) * 2017-09-07 2018-01-26 西安交通大学 光纤光栅振动/应力复合传感器
CN110095201A (zh) * 2019-04-10 2019-08-06 三峡大学 实时监测混凝土坝空间温度分布的分布式光纤测温系统及其方法
US20220341729A1 (en) * 2021-04-21 2022-10-27 Saudi Arabian Oil Company Fiber optic sensor network for subsurface impact protection system

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