CN207407830U - High precision and high sensitivity fiber Bragg grating strain sensor - Google Patents
High precision and high sensitivity fiber Bragg grating strain sensor Download PDFInfo
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- CN207407830U CN207407830U CN201721019795.6U CN201721019795U CN207407830U CN 207407830 U CN207407830 U CN 207407830U CN 201721019795 U CN201721019795 U CN 201721019795U CN 207407830 U CN207407830 U CN 207407830U
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Abstract
The utility model discloses a kind of high precision and high sensitivity fiber Bragg grating strain sensor, including：Optical fiber, surface have polyimide coating layer, and the fibre core of the optical fiber is equipped with the grating made of femtosecond laser carves grid, and the optical fiber at the grating both ends is weldingly fixed on through low-melting glass solder on two pedestals of the elastomer respectively.Due to having the optical fiber of polyimide coating layer using surface, grating on optical fiber is carved grid by femtosecond laser and is made, and the optical fiber at grating both ends is to be welded on by low-melting glass solder on two pedestals, so that the tensile strength higher of the fiber Bragg grating strain sensor formed, monitoring accuracy improves the requirement for three times of existing same type of sensor, meeting the highly sensitive big strain monitoring scope of high-precision in engineer application.
Description
Technical field
The utility model is related to strain transducer fields more particularly to a kind of high precision and high sensitivity fiber grating strain to pass
Sensor.
Background technology
In recent years, as the rapid development and field of civil engineering of optical fiber sensing technology are to the fast of monitoring structural health conditions demand
Speed increases, and fiber-optic grating sensor increasingly shows it in field of civil engineering compared to traditional mechanical electronic mode sensor
Advantage.And it is the important indicator for characterizing engineering structure safety to strain, and by analyzing structural strain, can obtain structure
The information such as dangerouse cross-section and degree of fatigue, and the service life of structure can be estimated.
Fiber Bragg grating strain sensor due to its intrinsic safety, Wavelength-encoding, light structure, corrosion-resistant, electromagnetism interference,
The outstanding advantages such as networking convenience, long-range real time on-line monitoring are widely applied.
Most of fiber Bragg grating strain sensor is all that make use of the emergent property of fiber grating in itself, i.e., grating is carried out
It stretches or squeezing causes screen periods to change, possessed elasto-optical effect causes effective refractive index also with outer to optical fiber in itself
The variation of boundary's stress state and change.The sensitivity of the emergent property of fiber grating in itself, i.e. 1.2 μ ε/pm, if fiber grating solution
The precision of instrument is adjusted to remove sensor error for 3pm, then the error of a whole set of sensor-based system is about 3.6 μ ε, to straining precision
More demanding occasion can not then meet its detection requirement.
For the application of engineering structure health strain monitoring, the encapsulating structure of fiber Bragg grating strain sensor is such as at present
(11 be sensor fixed position in Fig. 1, and 12 be optical fiber package position, and 13 be bare fibre, and 14 be acrylate-coated shown in Fig. 1
Layer optical fiber, 15 be sensor elastomer).
Using common acrylate coat optical fiber, as shown in Figure 2 (21 be Bragg gratings in Fig. 2, and 22 be fiber core,
23 be covering, and 24 be mechanical crackle, and 25 be acrylate-coated layer, and A is incident light, and B penetrates light to return), due to existing quarter grid skill
It has to divest acrylate-coated layer at the grid region of art limitation grating, it is naked grating to cause at grating, and passes through epoxy resin
The optical fiber at grating both ends is fixed on elastomer by the mode of glue sticking, the optical fiber fixed position point and sensor at grating both ends
The ratio of fixed position, that is, gauge length during use is almost 1:1.The resolution ratio of the sensor of this structure is naked grating
1.2 μ ε/pm of resolution ratio, due to the linear expansion coefficient of metal material using ordinary optic fibre grating and sensor elastomer
Limitation in outdoor environment so that can not use its enhanced sensitivity, usual range for the fiber Bragg grating strain sensor of ± 3000 microstrains
When, due to the coefficient of thermal expansion of measured material, it has been normal light in ± 4000 microstrains or so to cause actual measuring range
The limit of grid carrying, encapsulating structure, which has largely only served, protects grating not damage and effect easy for installation.
This 1.2 μ ε/pm sensors of resolution ratio are superimposed with the error of sensor in itself and the error of instrument demodulation again, generally
Substantial measurement errors are in ± 5pm or so when in use for sensor, in some places higher to required precision, it is difficult to meet need
It asks.
Utility model content
Based on the problems of prior art, the purpose of this utility model is to provide a kind of high precision and high sensitivity optical fiber
Grating strain transducer and preparation method thereof, measurement accuracy improve three times, and strain monitoring scope reaches ± 3000 μ ε, and can carry
Rise the tensile strength of sensor.
The purpose of this utility model is achieved through the following technical solutions：
The utility model embodiment provides a kind of high precision and high sensitivity fiber Bragg grating strain sensor, including：
Optical fiber, surface have polyimide coating layer, and the fibre core of the optical fiber is equipped with made of femtosecond laser carves grid
Grating, the optical fiber at the grating both ends are weldingly fixed on through low-melting glass solder on two pedestals of the elastomer respectively.
The high-precision that the utility model embodiment provides it can be seen from above-mentioned technical solution provided by the utility model is high
Sensitivity fiber Bragg grating strain sensor, its advantage are：
Due to optical fiber of the use surface with polyimide coating layer, the grating on optical fiber is to carve grid system by femtosecond laser
Into, and the optical fiber at grating both ends is to be welded on by low-melting glass solder on two pedestals so that the fiber grating of formation should
Become the tensile strength higher of sensor, monitoring accuracy is improved to three times of existing same type of sensor, is met high in engineer application
The requirement of the highly sensitive big strain monitoring scope of precision.And welded due to the use of low-melting glass solder, it can in packaging technology
Directly by metal pipe sleeve and optical fiber seal, without optical fiber surface is metallized, wellability is good, can reach level Hermetic Package；Change
It learns and stablizes preferably, seal and do not generate gas in the process, noresidue after sealing；Hermetic seal temperature is than relatively low, sealing temperature model
It encloses for 330 DEG C~380 DEG C, it is easily operated；Strong applicability, with respect to conventional package, the component life after being encapsulated using the product is long.
The packaging technology of more conventional epoxide-resin glue, fiber grating are welded by low-melting glass, and contact point stability is good, eliminates compacted
The drift of wavelength zero point caused by change.
Description of the drawings
It is required in being described below to embodiment in order to illustrate more clearly of the technical solution of the utility model embodiment
The attached drawing used is briefly described, it should be apparent that, the accompanying drawings in the following description is only some implementations of the utility model
Example, without creative efforts, can also be according to these attached drawings for those of ordinary skill in the art
Obtain other accompanying drawings.
Fig. 1 is the encapsulating structure schematic diagram for the existing fiber grating strain transducer that the prior art provides；
Fig. 2 is the optical fiber grating structure schematic diagram for the acrylate-coated layer that the prior art provides；
Fig. 3 is the overall structure diagram for the fiber Bragg grating strain sensor that the utility model embodiment provides；
Fig. 4 is that the femtosecond laser that the utility model embodiment provides carves grid, polyimide coating layer optical fiber grating structure shows
It is intended to；
In Fig. 1：11- sensors fixed position；12- optical fiber package positions；13- bare fibres；14- acrylate-coated layer light
It is fine；15- sensor elastomers；
In Fig. 2：21-Bragg gratings；22- fiber cores；23- coverings；24- mechanical crackles；25- acrylate-coated layers；
A- incident lights；B-, which is returned, penetrates light；
In Fig. 3：31- femtosecond lasers carve the grating of the polyimide coating layer of grid；32- elastomers；33- low-melting glasses weld
Contact；34- pedestals；
In Fig. 4：41- femtosecond lasers carve the Bragg gratings of grid；42- fiber cores；43- coverings；44- polyimide coatings
Layer；C- incident lights；D-, which is returned, penetrates light.
Specific embodiment
With reference to the particular content of the utility model, the technical scheme in the embodiment of the utility model is carried out it is clear,
It is fully described by, it is clear that the described embodiments are only a part of the embodiments of the utility model rather than whole implementation
Example.Embodiment based on the utility model, those of ordinary skill in the art are obtained without making creative work
Every other embodiment, belong to the scope of protection of the utility model.
As shown in Figure 3,4, the utility model embodiment provides a kind of high precision and high sensitivity fiber grating strain sensor
Device, including：
Optical fiber, surface are equipped with polyimide coating layer, and the fibre core of the optical fiber is equipped with made of femtosecond laser carves grid
Grating, the optical fiber at the grating both ends are weldingly fixed on through low-melting glass solder on two pedestals of the elastomer respectively.
In above-mentioned strain transducer, elastomer uses elastic alloy body, and tensile strength is not under the room temperature of the elastic alloy body
Less than 1225Mpa, elongation percentage is not less than 5%；
Two pedestals are bolted on the elastomer in above-mentioned strain transducer, in the utility model and are formed
Prestressed structure can be previously applied prestressing force to the grating on pedestal by adjusting bolt, and then realize the strain transducer
Negative strain monitoring function.
The utility model embodiment also provides a kind of production method of high precision and high sensitivity fiber Bragg grating strain sensor,
Including：
It is equipped with by femtosecond laser quarter grid on surface on the fiber core of polyimide coating layer and grating is made, utilize eutectic
The optical fiber at grating both ends is respectively welded on two pedestals by point glass solder, and two pedestals and optical fiber are placed on elastomer
On, two pedestals are screwed on pedestal respectively；
By one section of wavelength values and record being connected on fiber Bragg grating (FBG) demodulator under reading room temperature static state of optical fiber, pass through torsion
The screw of one of pedestal is moved to adjust prestretching, sees that wavelength data is adjusted to increase 3nm when adjusting, with screw thread glue fixed pedestal
Screw；
Said structure is integrally put into incubator and carries out aging, is then fabricated to fiber grating strain sensor according to technological process
Device.
The utility model embodiment is specifically described in further detail below.
As shown in Figure 3,4, the label 31 in Fig. 3 carves the grating of the polyimide coating layer of grid for femtosecond laser, and 32 be bullet
Property body, 33 be low-melting glass welding point, 34 be pedestal；Label 41 in Fig. 4 carves the Bragg gratings of grid for femtosecond laser, and 42
It is covering for fiber core, 43,44 be polyimide coating layer, and C is incident light, and D penetrates light to return.The fiber grating strain sensor
In device, using femtosecond laser quarter grid and the fiber grating with polyimide coating layer, the tensile strength of sensor is improved, is improved
The practicability of strain monitoring in engineering structure health monitoring；Using unique strain sensitization encapsulating structure so that fiber grating should
Become sensor accuracy class and improve three times, strain monitoring scope extends to ± 3000 μ ε.The fiber grating strain of the utility model
Big strain ability to bear of the sensor due to ensure that enclosed chip and packaging plastic, measurement range can meet for ± 3000 μ ε
The requirement of large strain sensing.
In the fiber Bragg grating strain sensor, pedestal, elastomeric material select elastic alloy, have high elasticity modulus,
High intensity, high temperature resistant, corrosion-resistant, nonmagnetic, elasticity modulus is basically unchanged in certain temperature range, and the coefficient of expansion is small, quality
The characteristics such as factor height.Tensile strength is not less than 1225Mpa under room temperature, and elongation percentage is not less than 5%.
The advantage that variations in refractive index inscription fiber grating is generated using femto-second laser pulse induction optical fiber fibre core is：Femtosecond
The nonlinear optical effect of laser generates the non-erasable grating extremely stablized as senser element；To 1000 degrees Celsius of pole
Hold stability；Through coat direct write, retain the better mechanical strength of optical fiber, retain the excellent properties of special coat, it is remote high
In the mechanical strength of conventional stripping-re-coating method fiber grating.
Using the optical fiber with polyimide coating layer, since polyimides is a kind of heat-resisting material, have high
The performances such as heat resistance, excellent chemical stability, good electrical insulating property and high mechanical properties, can guarantee in low-melting glass
Coat will not be burned under 270 DEG C of welding temperatures.
The low-melting glass used in the utility model is a kind of low temperature sealing glass solder, in packaging technology can directly by
Metal pipe sleeve and optical fiber seal, without optical fiber surface is metallized, wellability is good, can reach level Hermetic Package；Chemical stabilization
Preferably, seal and do not generate gas in the process, noresidue after sealing；For hermetic seal temperature than relatively low, sealing temperature scope is 330
DEG C~380 DEG C, it is easily operated；Strong applicability, with respect to conventional package, the component life after being encapsulated using the product is long.It is more conventional
The packaging technology of epoxide-resin glue, fiber grating are welded by low-melting glass, and contact point stability is good, eliminates creep and causes
Wavelength zero point drift.
The strain transducer of the utility model is during packaged fiber grating, first, utilizes low-melting glass solder
Two pedestals are welded on to the grating both ends of femtosecond laser quarter grid, polyimide coating layer；Secondly, by packaged pedestal and light
Grid are positioned on elastomer together, and pedestal is fixed using screw in the back side；Again, by optical fiber one section be connected to fiber grating demodulation
The wavelength values and record under room temperature static state are read on instrument；Finally, adjusted by twisting the screw of one of pedestal behind
Prestretching sees that wavelength data is adjusted to increase 3nm or so when adjusting, puts screw thread glue fixed screw.Entirety is put into incubator and carries out aging,
Then it is fabricated to fiber Bragg grating strain sensor according to technological process.
Using this wavelength after prestretching as zero point wavelength, when fiber Bragg grating strain sensor is axially compressed, pass
Wavelength change can be transmitted to (FBG) demodulator and be scaled negative strain automatically by sensor；When fiber Bragg grating strain sensor is axially stretched
When, wavelength change can be transmitted to (FBG) demodulator and be scaled normal strain automatically by sensor.
Since low-melting glass welding solves the problems, such as null offset；Femtosecond laser carves grid, polyimide coating layer light
Grid have very high tensile strength；On the premise of gauge length is constant, shorten the distance of grating both ends fixed point so that fiber grating should
The sensitivity for becoming sensor is increased to 0.4 μ ε/pm by 1.2 original μ ε/pm, engineer application strain monitoring range by it is original ±
1500 μ ε expand to ± 3000 μ ε.
In laboratory, the fiber Bragg grating strain sensor of the utility model is placed on calibration frame and carries out calibration experiment,
Fiber Bragg grating strain sensor strain measurement scope is ± 3000 μ ε, meets the big strain structure health monitoring of engineering structure health
Demand；Wavelength variable quantity is 3nm, and femtosecond laser carves grid, the grating of polyimide coating layer is bearing so big wavelength change
Amount；Precision is 1%F.S, and monitoring should be changed to accurately.
The fiber Bragg grating strain sensor of the utility model, has the advantages that：
Fiber Bragg grating strain sensor carves grid, polyimide coating layer grating, low smelting point glass using femtosecond laser
Welding technique so that the tensile strength higher of the strain transducer, monitoring accuracy are improved to original three times, and meeting engineering should
With the requirement of the highly sensitive big strain monitoring scope of middle high-precision.It is welded using low-melting glass solder, it can be direct in packaging technology
By metal pipe sleeve and optical fiber seal, without optical fiber surface is metallized, wellability is good, can reach level Hermetic Package；It is chemical steady
It is fixed preferable, it seals and does not generate gas in the process, noresidue after sealing；Than relatively low, sealing temperature scope is hermetic seal temperature
It is 330 DEG C~380 DEG C, easily operated；Strong applicability, with respect to conventional package, the component life after being encapsulated using the product is long.Relatively often
The packaging technology of epoxide-resin glue is advised, fiber grating is welded by low-melting glass, and contact point stability is good, eliminates creep and makes
Into wavelength zero point drift.The tensile strength of sensor is improved, improves the reality of strain monitoring in engineering structure health monitoring
The property used；Using specific strain sensitization encapsulating structure so that fiber Bragg grating strain sensor measurement accuracy improves three times, strain prison
It surveys scope and extends to ± 3000 μ ε.
The above is only the preferable specific embodiment of the utility model, but the scope of protection of the utility model is not
This is confined to, in the technical scope that any one skilled in the art discloses in the utility model, can be readily occurred in
Change or replacement, should be covered within the scope of the utility model.Therefore, the scope of protection of the utility model should
It is subject to the protection domain of claims.
Claims (3)
1. a kind of high precision and high sensitivity fiber Bragg grating strain sensor, which is characterized in that including：
Optical fiber, surface have polyimide coating layer, and the fibre core of the optical fiber is equipped with the grating made of femtosecond laser carves grid,
The optical fiber at the grating both ends is weldingly fixed on through low-melting glass solder on two pedestals of elastomer respectively；The elastomer
Using elastic alloy body, tensile strength is not less than 5% not less than 1225Mpa, elongation percentage under the room temperature of the elastic alloy body；Two
Pedestal is using elastic alloy pedestal, and for tensile strength not less than 1225Mpa, elongation percentage is not small under the room temperature of each elastic alloy pedestal
In 5%.
2. high precision and high sensitivity fiber Bragg grating strain sensor according to claim 1, which is characterized in that described two
Pedestal is bolted on the elastomer and forms prestressed structure.
3. high precision and high sensitivity fiber Bragg grating strain sensor according to claim 1, which is characterized in that the strain passes
The strain monitoring scope of sensor is ± 3000 μ ε.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721019795.6U CN207407830U (en) | 2017-08-15 | 2017-08-15 | High precision and high sensitivity fiber Bragg grating strain sensor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721019795.6U CN207407830U (en) | 2017-08-15 | 2017-08-15 | High precision and high sensitivity fiber Bragg grating strain sensor |
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| CN207407830U true CN207407830U (en) | 2018-05-25 |
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| CN201721019795.6U Active CN207407830U (en) | 2017-08-15 | 2017-08-15 | High precision and high sensitivity fiber Bragg grating strain sensor |
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| Date | Code | Title | Description |
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| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20190520 Address after: Room 609, Block B, 320 Pubin Road, Jiangpu Street, Nanjing City, Jiangsu Province, 210000 Patentee after: Nanjing Pinao Photoelectric Technology Co., Ltd. Address before: 314512 Second Floor of Building No. 26 Zikai East Road, Shimen Town, Tongxiang City, Jiaxing City, Zhejiang Province Patentee before: Zhejiang Zhiyuan Photoelectric Technology Co., Ltd. |
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| TR01 | Transfer of patent right |