CN101532891B - Fiber grating pressure sensor free from temperature influence - Google Patents
Fiber grating pressure sensor free from temperature influence Download PDFInfo
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- CN101532891B CN101532891B CN2009100220284A CN200910022028A CN101532891B CN 101532891 B CN101532891 B CN 101532891B CN 2009100220284 A CN2009100220284 A CN 2009100220284A CN 200910022028 A CN200910022028 A CN 200910022028A CN 101532891 B CN101532891 B CN 101532891B
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Abstract
The invention relates to a fiber grating pressure sensor free from temperature influence. The fiber grating pressure sensor is characterized in that a fiber grating is encapsulated in a tubular shell of which one end is open; one end of the fiber grating runs through a pore in the center of the unopened end face of the tubular shell, and a monomode fiber is connected with a fiber coupler; two sides of the fiber coupler are provided with four ports together; another port of one side connected with the fiber coupler is connected with and runs through the monomode fiber and is positioned in a fiber refractive index matching fluid; in two port of the other side of the fiber coupler, one port is connected with a broadband light source through the monomode fiber, and the other port is connected with a demodulation system through the monomode fiber; and the encapsulation of the fiber grating adopts the filling of a polymer to the tubular shell. The fiber grating pressure sensor only utilizes one fiber grating as a pressure sensitive element, can avoid the accurate sensing influence of the change of ambient temperature on a pressure signal, can change the stretching amount of reflection spectrum bandwidth of the fiber grating through the change of elasticity modulus of the polymer, and further changes the measuring precision and measuring range of the sensor.
Description
Technical field
The present invention relates to a kind of fiber bragg grating pressure sensor free from temperature influence, belong to sensor technical field, the pressure transducer technology that particularly a kind of sensitive element is a fiber grating.
Background technology
Along with the continuous maturation that the continuous development and the fiber grating of optical fiber sensitization technology writes technology, fiber grating is widely used in field of sensing technologies as a kind of new strain sensing element.Traditional pressure transducer kind is a lot, as the piezoresistive pressure sensor of based semiconductor material piezoresistive effect, based on the capacitance pressure transducer, of presser sensor capacitor, based on piezoelectric pressure indicator of material piezoelectric effect etc.The common feature of these pressure transducers is to be active structure, thereby is subjected to the interference of ambient electromagnetic field easily, and pressure-responsive speed is slow, and hysteresis quality is bigger, and sensitivity is low, and measurement range is narrower, also is difficult to be applied in inflammable, the explosive and corrosion-prone environment.With the sensitive element of fiber grating as pressure transducer, be characterized in the induction and the transmission of transducing signal are all finished in optical fiber, thereby probe is passive structures, signal is not subjected to the influence of ambient electromagnetic field, dependable performance, and can under high temperature, extreme environment such as inflammable, explosive and perishable, use.Yet,, bring the temperature, pressure cross sensitivity because the variation of temperature and pressure all will cause moving of fiber grating centre wavelength.Therefore, how can effectively solve the cross sensitivity problem of temperature and pressure, promptly eliminating Temperature Influence in gaging pressure is the key of this type of sensor practicability.
Sun An, Qiao Xueguang etc. once proposed a kind of fiber bragg grating pressure sensor based on polymer encapsulated (Sun An, Qiao Xueguang, Jia Zhenan, Guo group, Chen Changyong, high pressure resistant optical fiber Bragg raster pressure sensing technology research, the photon journal, 2004,33 (7)), be characterized in, before the packaged fiber grating, adopt the heat-conducting type organic silica gel to apply curing,, prevent from course of exerting pressure, to occur the chirp phenomenon of fiber grating to reduce bonding and the friction between encapsulating material and the tubular shell.But this structure also need be added temperature compensation means in actual pressure is measured, can keep the accuracy of measuring.
Summary of the invention
The technical matters that solves
For fear of the deficiencies in the prior art part, the present invention proposes a kind of fiber bragg grating pressure sensor free from temperature influence, utilize coarse tubular shell inwall and polymkeric substance tight bond to increase the chirp value of fiber grating, and then the bandwidth demodulation of employing fiber grating, because temperature change can not influence the variation of bandwidth, can guarantee that therefore sensor avoids Temperature Influence.
Technical scheme
Basic thought of the present invention is: fiber grating is encapsulated in the polymkeric substance, around the polymkeric substance under the limited situation, its exposed end produces gradient strain at its end face near zone along its central axis because of being subjected to well-distributed pressure, the fiber grating that causes being encapsulated in this gradient strain regions produces axial strain heterogeneous, thereby makes the reflectance spectrum generation chirp phenomenon of fiber grating and the broadening of bandwidth.Meanwhile, the variation of environment temperature can only cause the drift of fiber grating foveal reflex wavelength, and can not bring the broadening of reflection spectrum bandwidth.Therefore, can obtain the size of force value by demodulation reflection spectrum bandwidth information.
The invention is characterized in: fiber grating 1 is encapsulated in the tubular shell 3 of an end opening, an end of fiber grating 1 by tubular shell 3 not the aperture at open end center pass and single-mode fiber 9 be connected with fiber coupler 5; Fiber coupler 5 both sides have four ports, and another port connection of a side that is connected with fiber coupler 5 places optical fibre refractivity matching fluid 8 by single-mode fiber 9; Two ports of fiber coupler 5 opposite sides, an end connects wideband light source 6, one ends by single-mode fiber 9 and connects demodulating system 7 by single-mode fiber 9; Packaged fiber grating 1 adopts polymkeric substance 2 fillings in tubular shell 3.
Described tubular shell 3 is: the end at hollow cylinder 4 is to adopt the protection bonnet 11 that is threaded, and the center of protection bonnet 11 is provided with the aperture that passes through for single-mode fiber 9.
The grid region part of fiber grating is encapsulated in the almost gradient strain zone of polymkeric substance 2, and this zone is 5-20mm apart from the scope of polymkeric substance pressure-bearing surface 10.
Beneficial effect
Fiber bragg grating pressure sensor free from temperature influence of the present invention, only utilize a fiber grating as pressure-sensing device, can avoid simultaneously variation of ambient temperature to the accurate perception influence of pressure signal, but also can change the broadening amount of fiber grating reflection spectrum bandwidth, and then change the measuring accuracy and the range of this sensor by the elastic modulus that changes polymkeric substance.Simultaneously, advantage such as that this sensor has is simple in structure, be easy to realize, measurement range is big on the technology is fit to the sensing measurement of big pressure such as oil well or deep water very much.
Description of drawings
Fig. 1 is fiber grating bandwidth tuning principle schematic under the gradient strain.The cycle variation characteristic of fiber grating before the corresponding respectively encapsulation polymkeric substance of Fig. 1 (a) and Fig. 1 (b) pressurized and behind the pressurized.
Fig. 2 is encapsulation polymkeric substance exposed end its axial strain distribution curve under the well-distributed pressure effect that utilizes the finite element method analog computation to obtain.
Fig. 3 is the fiber bragg grating pressure sensor structural drawing of employing mode 1.
Fig. 4 is the fiber bragg grating pressure sensor structural drawing of employing mode 2.
1, fiber grating; 2, polymkeric substance (polyurethane or acrylate); 3, tubular shell; 4, hollow cylinder; 5, fiber coupler; 6, wideband light source; 7. demodulating system; 8, index-matching fluid; 9, single-mode fiber; 10, polymkeric substance pressure-bearing surface; 11, protection bonnet.
Embodiment
Now in conjunction with the embodiments, accompanying drawing is further described the present invention:
Embodiment 1: consult accompanying drawing 3, fiber grating adopts Fiber Bragg Grating FBG 1, Fiber Bragg Grating FBG 1 is encapsulated in the tubular metal housing 3 of an end opening, an end of fiber grating 1 by tubular shell 3 not the aperture at open end center pass and single-mode fiber 9 is connected with 2 * 2 3dB fiber coupler 5; Fiber coupler 5 both sides have four ports, and another port connection of a side that is connected with fiber coupler 5 places optical fibre refractivity matching fluid 8 by single-mode fiber 9; Two ports of fiber coupler 5 opposite sides, an end connects wideband light source 6, one ends by single-mode fiber 9 and connects demodulating system 7 by single-mode fiber 9; Packaged fiber grating 1 adopts 2 fillings of polymkeric substance acrylate in tubular shell 3.
Installation step is as follows: tubular shell first 3 of (1) processing also makes its inwall keep coarse, the polymkeric substance 2 that is beneficial to encapsulate can with its tight bond; (2) remove the coat of fiber grating 1 part to be packaged, can effectively avoid the be stretched reverse drift of rear center's wavelength of fiber grating 1 like this; (3) fiber grating 1 is placed on tubular shell 3 central axis and to it carry out prestretched, then the polymkeric substance 2 for preparing is filled in the tubular shell 3; (4) after the polymkeric substance 2 of filling solidifies, this sensor is calibrated measurement.During measurement, the light that wideband light source 6 sends arrives the fiber grating 1 that is encapsulated in the polymkeric substance 2 through fiber coupler 5, arrives demodulating system 7 by fiber coupler 5 behind the reflected signal.Simultaneously on polymkeric substance pressure-bearing surface 10, apply well-distributed pressure, the broadened bandwidth amount of measuring optical fiber grating 1 reflectance spectrum, finally the broadening amount by bandwidth obtains applied pressure value size.
Embodiment 2: consult accompanying drawing 4, adopt the fiber bragg grating pressure sensor structural drawing of packaged type 2.Encapsulation step is as follows: (1) processing alloy tubular shell 4 and protection bonnet 11, and both can be connected by sealing thread, the inwall of same tubular shell 4 is worn into uneven surface; (2) remove the coat of Fiber Bragg Grating FBG 1 packed part; (3) place fiber grating 1 and on tubular shell 4 central axis and to it, carry out prestretched, then the polymer polyurethane 2 for preparing is encapsulated in the tubular shell 4; (4) will protect bonnet 11 to be added on the tubular shell 4, calibrate measurement after the polymkeric substance 2 of encapsulation solidifies.Its measuring method is with shown in Figure 3 identical.
Claims (3)
1. fiber bragg grating pressure sensor free from temperature influence, it is characterized in that: fiber grating (1) is encapsulated in the tubular shell (3) of an end opening, an end of fiber grating (1) by tubular shell (3) not the aperture at open end center pass and be connected with fiber coupler (5) by single-mode fiber (9); Fiber coupler (5) both sides have four ports, and another port of a side that is connected with fiber grating (1) places optical fibre refractivity matching fluid (8) by single-mode fiber (9); Two ports of fiber coupler (5) opposite side, an end connects wideband light source (6) by single-mode fiber (9), and an end connects demodulating system (7) by single-mode fiber (9); Packaged fiber grating (1) adopts polymkeric substance (2) filling in tubular shell (3); The grid region part of fiber grating is encapsulated in the almost gradient strain zone of polymkeric substance (2), and this zone is 5-20mm apart from the scope of polymkeric substance pressure-bearing surface (10).
2. fiber bragg grating pressure sensor free from temperature influence according to claim 1; it is characterized in that: described tubular shell (3) is: the end at hollow cylinder (4) is to adopt the protection bonnet (11) that is threaded, and the center of protection bonnet (11) is provided with the aperture that passes through for single-mode fiber (9).
3. any fiber bragg grating pressure sensor free from temperature influence according to claim 1 is characterized in that: described polymkeric substance is acrylate or polyurethane.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2009100220284A CN101532891B (en) | 2009-04-15 | 2009-04-15 | Fiber grating pressure sensor free from temperature influence |
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| CN2009100220284A CN101532891B (en) | 2009-04-15 | 2009-04-15 | Fiber grating pressure sensor free from temperature influence |
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| CN101532891A CN101532891A (en) | 2009-09-16 |
| CN101532891B true CN101532891B (en) | 2011-01-19 |
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Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101788309B (en) * | 2010-01-19 | 2011-10-26 | 合肥工业大学 | Fiber grating sensing signal interference demodulation device free from heat influence of driving device |
| CN103411727B (en) * | 2013-07-26 | 2015-08-05 | 西北工业大学 | For the tonometric fibre optic compression sensor of pneumatic plant and measuring method thereof |
| CN106500906B (en) * | 2016-12-14 | 2022-03-01 | 北京交通大学 | Air pressure sensor based on coreless optical fiber |
| CN107687817B (en) * | 2017-07-20 | 2019-11-29 | 北京航天控制仪器研究所 | A kind of miniaturization flexible optical fibre grating strain transducer |
| CN110864830A (en) * | 2018-08-27 | 2020-03-06 | 南京采薇且歌信息科技有限公司 | Fiber grating sensor suitable for wide temperature range |
| CN111537120A (en) * | 2020-06-03 | 2020-08-14 | 华北电力大学 | Fiber grating sensor for monitoring internal pressure of power transformer |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1654926A (en) * | 2005-03-15 | 2005-08-17 | 南开大学 | Linear chirp optical fiber grating based two-dimensional stress sensor |
| CN1995924A (en) * | 2007-01-04 | 2007-07-11 | 中国人民解放军海军工程大学 | Fiber-optic grating sensor |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1654926A (en) * | 2005-03-15 | 2005-08-17 | 南开大学 | Linear chirp optical fiber grating based two-dimensional stress sensor |
| CN1995924A (en) * | 2007-01-04 | 2007-07-11 | 中国人民解放军海军工程大学 | Fiber-optic grating sensor |
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| Title |
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| 于永森等.一种基于啁啾光纤光栅温度不敏感的应力传感器.半导体光电.2005,第26卷(第4期), * |
| 王宏亮等.一种补偿式光纤光栅传感器压力特性研究.光电子.激光.2005,第16卷(第3期), * |
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