CN106524937A - Fiber bragg grating strain device - Google Patents

Fiber bragg grating strain device Download PDF

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Publication number
CN106524937A
CN106524937A CN201611019430.3A CN201611019430A CN106524937A CN 106524937 A CN106524937 A CN 106524937A CN 201611019430 A CN201611019430 A CN 201611019430A CN 106524937 A CN106524937 A CN 106524937A
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Prior art keywords
substrate
fiber bragg
bragg grating
compensator
strain sensor
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CN201611019430.3A
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CN106524937B (en
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于长江
张治国
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Beijing University of Posts and Telecommunications
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Beijing University of Posts and Telecommunications
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G01B11/165—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by means of a grating deformed by the object

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optical Transform (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

The invention provides a fiber bragg grating strain sensor. The sensor comprises a substrate, two compensation arms and fiber bragg gratings, wherein the two compensation arms are symmetrically arranged on two sides of the substrate; one side of an upper end of each compensation arm, which is close to a substrate center, is provided with an optical fiber fixing point; one side of a lower end of the each compensation arm, which is far away from the optical fiber fixing point, is fixed to the substrate; and the fiber bragg gratings are arranged on the two compensation arms through the optical fiber fixing points. In the invention, an expansion direction of the compensation arms is opposite to an expansion direction of the substrate so that expansion quantities and the expansion directions of the substrate and the compensation arms are different, expansion quantities of the fiber bragg gratings are compensated and a temperature cross interference is eliminated.

Description

A kind of fiber grating strain device
Technical field
The present invention relates to technical field of optical fiber, more particularly, to the fiber grating strain device for eliminating temperature impact.
Background technology
Fiber Bragg Grating FBG is a kind of optical pickocff very with practical value, with small volume, electromagnetism interference The advantages of.As fiber grating has the advantages that small volume, splice loss, splice attenuation are little, is compatible with full optical fiber, can imbed intellectual material, and And change of its resonance wavelength to external environments such as temperature, strain, refractive index, concentration is more sensitive, bridge, tunnel, The aspects such as large and complex structure deformation monitoring and petrochemical industry, power supply facilities temperature monitoring such as building are increasingly widely applied.
At present, Fiber Bragg Grating FBG is in actual sensing measurement, there is strain and Temperature cross-over tender subject, strain and The change of temperature can make its bragg wavelength change.Fiber Bragg grating strain sensor be which results in measuring strain When, temperature interference can be introduced.Current numerous studies work is using double grating or other structures, while measurement temperature and should Become, then temperature-compensating is carried out to dependent variable.These methods are used mostly multiple gratings or system architecture is complicated.Therefore, make Simple structure, the fiber Bragg grating strain sensor of exclusion temperature interference are hot issues in current strain sensing field.
The content of the invention
The present invention provides a kind of fiber grating strain device for overcoming the problems referred to above or solving the above problems at least in part.
According to an aspect of the present invention, there is provided a kind of fiber Bragg grating strain sensor, including：
Substrate；
Two compensator arms, are symmetricly set on the both sides of the substrate, and the upper end of the compensator arm is close to the substrate center Side optical fiber fixing point is set, the lower end of the compensator arm is fixed with the substrate away from the side of the optical fiber fixing point； And
Fiber grating, is arranged on two compensator arms by optical fiber fixing point；
The relation of the compensator arm and substrate is：
a1L1+afLf-2a2L2=0
Wherein, a1For the linear expansion coefficient of substrate, a2For the linear expansion coefficient of compensator arm, afLine for fiber grating expands Coefficient, L1For the effective length of substrate, L2For the effective length of compensator arm, LfFor the distance of two optical fiber fixing points.
The application is by arranging the expansion direction of compensator arm and the expansion direction of substrate conversely, making this fiber grating strain device In variation of ambient temperature, by substrate and the difference of the swell increment and expansion direction of compensator arm, the swollen of fiber grating is compensate for Bulk, realizes temperature self-compensation, eliminates Temperature cross-over interference.
Description of the drawings
Fig. 1 is the structural representation of fiber Bragg grating strain sensor in prior art；
Fig. 2 is the top view of the fiber Bragg grating strain sensor according to the embodiment of the present invention；
Fig. 3 is the side view of the fiber Bragg grating strain sensor according to the embodiment of the present invention.
Specific embodiment
With reference to the accompanying drawings and examples, the specific embodiment of the present invention is described in further detail.Hereinafter implement Example is for illustrating the present invention, but is not limited to the scope of the present invention.
Fig. 1 shows the structural representation of fiber Bragg grating strain sensor in prior art.As illustrated, the device is only wrapped Substrate 101 is included, substrate 101 arranges the V-shaped groove 102 for placing fiber grating 103 along changing direction.As fiber grating 103 is straight Connect and contact with substrate, in actual sensing measurement, there is strain and Temperature cross-over tender subject, strain and the change of temperature can Make its bragg wavelength change, cause fiber Bragg grating strain sensor temperature interference to be introduced in measuring strain.
Fig. 2 shows the top view of a fiber Bragg grating strain sensor disclosed by the invention, as illustrated, the device bag 201, two compensator arms 202 of substrate and fiber grating 203 are included, compensator arm 202 is symmetricly set on the both sides of substrate 201, compensated The upper end edge strain sensing direction of arm 202 arranges V-shaped groove 204 and arranges optical fiber in the side for being close to the substrate center and fixes Point, the lower end of the compensator arm are fixed with the substrate away from the side of the optical fiber fixing point 205, fiber grating, by light Fine fixing point is arranged in two V-shaped grooves 204.This device when temperature sense is received, as substrate can extend to both sides, and two Individual compensator arm is extended towards towards substrate, therefore has reached the effect of adaptive equalization temperature.
By arranging the expansion direction of compensator arm and the expansion direction of substrate conversely, making this fiber grating strain device in environment During temperature change, by substrate and the difference of the swell increment and expansion direction of compensator arm, the swell increment of fiber grating is compensate for, it is real Show temperature self-compensation, eliminate Temperature cross-over interference.
In one embodiment, two compensator arms 202 can be at 1/3, the 2/3 of 201 length of substrate, it is also possible to be arranged on At 1/4, the 3/4 of 201 length of substrate.
Fig. 3 shows the side view of the present invention.As figure shows, the compensator arm includes basic blocks 2021 and extension block 2022, basic blocks 2021 are fixedly connected with the substrate；Extension block 2022 is arranged on the basic blocks upper end, institute with being integrally formed The upper surface for stating extension block arranges V-shaped groove 2023 along strain sensing direction.
In one embodiment, the cross section of basic blocks is square, and a foursquare center line and strain sensing Direction is consistent；The cross section of the compensator arm is rectangle, and the rectangular width is consistent with the length of side of the cross section of basic blocks.
In one embodiment, the distance of the one end away from substrate center of two compensator arms is limited as the substrate Effective length L1, the extension block along strain sensing direction length and the basic blocks along strain sensing direction length it Effective length L of the difference for the compensator arm2, the distance between two optical fiber fixing points are Lf, a1For the linear expansion coefficient of substrate, Linear expansion coefficients of the a2 for compensator arm, afFor the linear expansion coefficient of fiber grating, then substrate need to meet below equation with compensator arm, The strain measurement of temperature self-compensation is capable of achieving then：
a1L1+afLf-2a2L2=0.
The applicant discloses the derivation of above-mentioned formula：
The central wavelength lambda of fiber grating firstBMeet bragg's formula：
λB=2neffΛ
Wherein, neffFor fiber grating equivalent refractive index, Λ is screen periods.
Further, when fiber Bragg grating strain sensor only temperature influence, fiber grating temperature influence itself, in There is drift in cardiac wave length, drift value is：
Wherein, Δ T be temperature variation, βTFor temperature coefficient.
Further, substrate outwards expands Δ L1, compensator arm inwardly expands Δ L2, therefore, substrate and compensator arm are always swollen Bulk Δ L0Computing formula is：
ΔL0=Δ L1-ΔL2=a1ΔTL1-2a2ΔTL2
Further, substrate and compensator arm overall expansion amount Δ L0, make extra dependent variableMake For fiber grating, during now fiber grating is caused the additional strain that substrate and compensator arm expansion bring to cause by temperature Heart wavelength variable quantity is：
Wherein, βεFor strain-responsive coefficient；Now changing total amount by the fiber bragg grating center wavelength that temperature causes is：
Further, fiber Bragg grating strain sensor to be made is temperature independent, need to meet formula Δ λB=0, then：
a1L1+afLf-2a2L2=0
Wherein,It is defined as the linear expansion coefficient of fiber grating.It is achieved that eliminating temperature to strain measurement Cross jamming.
In one embodiment, the substrate and compensator arm are metal material.The purpose of so design is that metal can Strained with good transmission, also, as the occasion of the strain transducer application of the present invention is welded to the cantilever of metal mostly On beam or in other metal structures, preferably can be welded using strain transducer made by metal.
In one embodiment, linear expansion coefficient of the linear expansion coefficient of the compensator arm more than the substrate, due to mending The expansion for repaying arm generation is inwardly expansion, and substrate is outwards expansion, and when the temperature increases, substrate and basic blocks are all outwards swollen Rise, now the inwardly swollen amount of extension block is swollen have to be larger than the amount that substrate inwardly expands, the swell increment of ability compensated optical fiber.
In one embodiment, two rectangular through-holes are symmetrical arranged in the middle part of the substrate, are so arranged and is advantageous in that, one Aspect can increase the susceptibility of substrate expansion, on the other hand ensure that substrate expansion is uniform using rectangular design, more conducively Eliminate interference of the temperature to strain measurement.
In one embodiment, the material of the compensator arm is stainless steel.
In one embodiment, the material of the substrate is invar.
As stainless linear expansion coefficient is much larger than the linear expansion coefficient of invar, the coefficient of expansion of substrate is lower, substrate Lower with the overall expansion amount of optical fiber, the design swell increment of compensator arm is also less, and the cumulative volume of this strain transducer is also more It is little.
In one embodiment, optical fiber cloth is inscribed on fiber core using ultraviolet argon laser and phase mask plate method Glug grating, the centre wavelength of fiber grating is 1550nm, and optical fiber coating divests length for 13.0mm, and the line of fiber grating is swollen Swollen coefficient is af=12.0 × 10-6/℃。
From invar as substrate material, the linear expansion coefficient a of invar1=1.8 × 10-6/ DEG C, compensator arm is chosen stainless Steel, stainless linear expansion coefficient a2=16 × 10-6/ DEG C, therefore can be obtained by above-mentioned formula, L1For 20.7mm, L2For 3.85mm. Under fiber Bragg grating strain sensor is only by temperature action, the structure design size meets a1L1+afLf-2a2L2=0, Neng Gouda To temperature reverses compensation effect, the strain measurement of temperature self-compensation is realized.
Finally, the present processes are only preferably embodiment, are not intended to limit protection scope of the present invention.It is all Within the spirit and principles in the present invention, any modification, equivalent substitution and improvements made etc. should be included in the protection of the present invention Within the scope of.

Claims (8)

1. a kind of fiber Bragg grating strain sensor, it is characterised in that include：
Substrate；
Two compensator arms, are symmetricly set on the both sides of the substrate, and the upper end of the compensator arm is close to the one of the substrate center Side arranges optical fiber fixing point, and the lower end of the compensator arm is fixed with the substrate away from the side of the optical fiber fixing point；And
Fiber grating, is arranged on two compensator arms by optical fiber fixing point；
The relation of the compensator arm and substrate is：
a1L1+afLf-2a2L2=0
Wherein, a1For the linear expansion coefficient of substrate, a2For the linear expansion coefficient of compensator arm, afFor the linear expansion coefficient of fiber grating, L1For the effective length of substrate, L2For the effective length of compensator arm, LfFor the distance of two optical fiber fixing points.
2. fiber Bragg grating strain sensor as claimed in claim 1, it is characterised in that the compensator arm includes：
Basic blocks, are fixedly connected with the substrate；And
Extension block, is arranged on the basic blocks upper end with being integrally formed, and the upper surface of the extension block is set along strain sensing direction V-shaped groove is put, the optical fiber fixing point is arranged in the V-shaped groove；
Wherein, length difference with the basic blocks along the length in strain sensing direction of the extension block along strain sensing direction is The effective length of the compensator arm.
3. fiber Bragg grating strain sensor as claimed in claim 2, it is characterised in that the distance of two basic blocks is institute State the effective length of substrate.
4. the fiber Bragg grating strain sensor as described in claim 1-3 any one, it is characterised in that the substrate and compensation Arm is metal material.
5. fiber Bragg grating strain sensor as claimed in claim 4, it is characterised in that the linear expansion coefficient of the compensator arm is big In the linear expansion coefficient of the substrate.
6. fiber Bragg grating strain sensor as claimed in claim 5, it is characterised in that two are symmetrical arranged in the middle part of the substrate Rectangular through-hole.
7. fiber Bragg grating strain sensor as claimed in claim 6, it is characterised in that the material of the compensator arm is stainless Steel.
8. fiber Bragg grating strain sensor as claimed in claim 7, it is characterised in that the material of the substrate is invar.
CN201611019430.3A 2016-11-17 2016-11-17 A kind of fiber grating strain device Active CN106524937B (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107328369A (en) * 2017-06-22 2017-11-07 石家庄铁道大学 Fiber Bragg grating strain sensor
CN108489415A (en) * 2018-06-01 2018-09-04 南京梦联桥传感科技有限公司 A kind of fibre optic strain sensor with temperature self-compensation
CN110057480A (en) * 2019-05-21 2019-07-26 衢州学院 A kind of the fiber grating torque sensor and its installation method of forked type conjugated structure
CN116067298A (en) * 2023-04-06 2023-05-05 山东省科学院激光研究所 Optical fiber strain sensor structure

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000221011A (en) * 1999-02-02 2000-08-11 Kyowa Electron Instr Co Ltd Optical fiber type strain gage
CN101201430A (en) * 2007-12-03 2008-06-18 北京航空航天大学 Temperature compensating device for optical fiber and grating
CN201535667U (en) * 2009-09-18 2010-07-28 昆明理工大学 Double tube fiber Bragg grating strain sensor insensitive to temperature change
CN102853778A (en) * 2012-08-06 2013-01-02 杭州珏光物联网科技有限公司 Fiber grating strain sensor
CN105333833A (en) * 2015-10-27 2016-02-17 北京航空航天大学 Temperature-independent fiber bragg grating strain sensor
CN205373657U (en) * 2015-07-30 2016-07-06 电子科技大学 Enamel amber strain sensor device based on sensitization structure temperature compensating
CN206192288U (en) * 2016-11-17 2017-05-24 北京邮电大学 Fiber grating effector

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2000221011A (en) * 1999-02-02 2000-08-11 Kyowa Electron Instr Co Ltd Optical fiber type strain gage
CN101201430A (en) * 2007-12-03 2008-06-18 北京航空航天大学 Temperature compensating device for optical fiber and grating
CN201535667U (en) * 2009-09-18 2010-07-28 昆明理工大学 Double tube fiber Bragg grating strain sensor insensitive to temperature change
CN102853778A (en) * 2012-08-06 2013-01-02 杭州珏光物联网科技有限公司 Fiber grating strain sensor
CN205373657U (en) * 2015-07-30 2016-07-06 电子科技大学 Enamel amber strain sensor device based on sensitization structure temperature compensating
CN105333833A (en) * 2015-10-27 2016-02-17 北京航空航天大学 Temperature-independent fiber bragg grating strain sensor
CN206192288U (en) * 2016-11-17 2017-05-24 北京邮电大学 Fiber grating effector

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107328369A (en) * 2017-06-22 2017-11-07 石家庄铁道大学 Fiber Bragg grating strain sensor
CN108489415A (en) * 2018-06-01 2018-09-04 南京梦联桥传感科技有限公司 A kind of fibre optic strain sensor with temperature self-compensation
CN110057480A (en) * 2019-05-21 2019-07-26 衢州学院 A kind of the fiber grating torque sensor and its installation method of forked type conjugated structure
CN110057480B (en) * 2019-05-21 2024-02-06 衢州学院 Fiber bragg grating torque sensor with fork-shaped conjugated structure and installation method thereof
CN116067298A (en) * 2023-04-06 2023-05-05 山东省科学院激光研究所 Optical fiber strain sensor structure
CN116067298B (en) * 2023-04-06 2023-06-09 山东省科学院激光研究所 Optical fiber strain sensor structure

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