CN103791957A - Fiber flow sensor based on metal-film-coated and long-period fiber bragg gratings - Google Patents
Fiber flow sensor based on metal-film-coated and long-period fiber bragg gratings Download PDFInfo
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- CN103791957A CN103791957A CN201410076437.3A CN201410076437A CN103791957A CN 103791957 A CN103791957 A CN 103791957A CN 201410076437 A CN201410076437 A CN 201410076437A CN 103791957 A CN103791957 A CN 103791957A
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Abstract
The invention relates to a fiber flow sensor based on metal-film-coated and long-period fiber bragg gratings. The fiber flow sensor comprises a section of ordinary single mode fiber, a long-period fiber bragg grating A and a long-period fiber bragg grating B are written into a fiber core of the ordinary single mode fiber, and the surface of a wrapping layer of the fiber where the long-period fiber bragg grating B is located is coated with a layer of metal film. A pump is used for injecting a laser into the long-period fiber bragg grating A, the pump light is coupled into the fiber wrapping layer, heat exchanging is carried out between the wrapping layer of the long-period fiber bragg grating B and the metal film, the heat field distribution is affected, and due to the fact that the change of the heat field distribution is measured through the long-period fiber bragg grating B, the purpose of flow sensing is achieved. The fiber bragg grating technology and hot line type flow sensing technology are combined, and therefore the fiber flow sensor has the advantages of being easy to manufacture, small in size, high in sensitivity, low in cost and the like.
Description
Technical field
The present invention relates to a kind of fiber optic sensing device, be specifically related to a kind of optic flow sensor based on metal-coated membrane long period fiber grating.
Background technology
The measurement of flow velocity, flow in the industrial processes such as oil, chemical industry, medicine, energy measurement, environmental monitoring in occupation of very important status.Therefore, flow velocity, flow sensor are indispensable senser elements in fluid detection and control procedure.Traditional mechanical type flow velocity, flow sensor measuring error is large, precision is low.For example, adopt the current meter of hyperacoustic Flow speed measurer, electromagnetic current meter or acoustical Doppler effect etc., although measuring accuracy is higher, the high and easy electromagnetic wave interference of its cost.Along with the development of optical fiber technology, a lot of flow velocity of optical, flow sensors based on optical principle are there are.
In recent years, optic flow sensor enjoys people's extensive concern because of its unique advantage.Optic flow sensor is adopt characteristic (as intensity, phase place, frequency, wavelength etc.) that light transmits the time in optical fiber can be subject to the modulation of flow and the principle that corresponding modulation voltage is demodulated into rate of flow of fluid is realized.Compared with traditional flow sensor, optic flow sensor tool has the following advantages: (1) accuracy, highly sensitive; (2) high pressure resistant, high temperature resistant, anti-electromagnetic interference (EMI), safe and reliable under inflammable, explosive environments; (3) bandwidth, dynamic range are wide; (4) be convenient to telemeasurement and control; (5) volume is little, quality is light.Owing to thering is anti-electromagnetic interference (EMI), anti-neighbourhood noise, the features such as electric insulating quality and self-security, therefore optic flow sensor will have huge marketable value.
Traditional flow sensor based on optical fiber mainly contains optical fiber low discharge sensor, optical fiber doppler flowmeter, optical fiber turbine flow transducer, optical fiber vortex flow sensors etc.
Low discharge optic flow sensor, based on Fresnel drageffect measuring flow, has been realized the measurement of specific area fluid low discharge.But, a little less than fluid flow less makes transducing signal, be unfavorable for the detection of signal, reduce the accuracy of measuring.Now, sensors with auxiliary electrode were only meets the needs of oil, well flow measurement, is difficult to be widely used in the measurement of fluid.
Optical fiber doppler flowmeter is the flowing velocity that the Doppler effect based on light is determined fluid, can realize the contactless high-precision of speed of moving body and measure.Optical fiber doppler flowmeter can be advantageously applied to places such as solving Large Diameter Pipeline, thick tube wall, cement lining.But in fluid, molecule or bubble are random existence, thereby have affected its measuring accuracy.
Optical fiber turbine flow transducer is on the basis of conventional turbine flow measurement principle, adopts multimode optical fiber to replace internal magnetization sensor and the reflection-type optical fiber turbine flow transducer that forms.It has linearity, reproducible, anti-electromagnetic interference capability strong, measure the advantages such as dynamic range is large.But its application is confined to that scene is not charged, the test of low-viscosity oil gas flow.
Optical fiber vortex flow sensors is a kind of vortex flow sensors that produces eddy current using optical fiber as non-linear type fluid.Utilize the release frequency of vortex to be directly proportional to flow velocity, obtain fluid flow thereby just can measure frequency.Because optical fiber is for a long time in fluid, therefore optical fiber may produce the phenomenons such as fracture, wearing and tearing.
At present, Fiber Bragg Grating technology development is very rapid, and the sensor of the physical quantitys such as temperature based on fiber grating, pressure, vibration, humidity also emerges in an endless stream.Aspect measurement of fluid flow, target type fiber grating flowmeter combines single or multiple fiber gratings, semi-girder and target formula disk, has improved many reference amounts, security and the accuracy of systematic survey, applies very extensive.The basic functional principle of this class sensor is to be used on target formula disk and while transferring on cantilever by transmission rod when the mobile masterpiece producing of fluid, the torsional deformation of suspended wall will cause fiber grating deformation, cause the wave length shift of fiber grating, thereby can obtain by the variable quantity of measuring wavelength the flow value that will measure.But this sensor construction is comparatively complicated, measurement result and semi-girder parameter are closely related, and are difficult to the formulation of the standard that realizes.
In research in sum, existing optic flow sensor respectively has feature in performance and method for making, but all has shortcoming separately, embody a concentrated reflection of sensing arrangement relative complex, volume greatly, serviceable life is partially short, measuring accuracy is low and price is high.Wide application based on optical fibre flowmeter and the active demand to novel optical fiber flow sensor.
Summary of the invention
For existing fiber flow sensor complex process, serviceable life is short, volume is large, the problem such as expensive, the object of the present invention is to provide a kind of optic flow sensor based on metal-coated membrane long period fiber grating.
The technical solution used in the present invention is:
Comprise one section of general single mode fiber, write long period fiber grating A and long period fiber grating B in its fibre core, the cladding surface of long period fiber grating B is coated with layer of metal film; Utilize pumping that laser is injected to long period fiber grating A, pump light is coupled in fibre cladding, and in covering and the metallic film generation heat interchange of long period fiber grating B, affects heat field and distribute, measure it by long period fiber grating B simultaneously and change, reach the object of flow sensing.
The beneficial effect that the present invention has is:
The present invention combines Fiber Bragg Grating technology with hot-wire flow sensing technology, have and make the advantages such as simple, volume is little, highly sensitive, cost is lower, can be used for the measurement of small gas flow.
Accompanying drawing explanation
Fig. 1 is the structural representation of the optic flow sensor based on metal-coated membrane long period fiber grating.
Fig. 2 is a kind of pick-up unit figure of the optic flow sensor part based on metal-coated membrane long period fiber grating.
In figure: 1, single-mode fiber, 2, long period fiber grating A, 3, long period fiber grating B, 4, metallic film, 5, wideband light source, 6, pump laser, 7, wavelength division multiplexer, 8, hot-wire flow sensing unit, 9, spectroanalysis instrument.
Embodiment
Below in conjunction with the drawings and specific embodiments, the invention will be further described.
As shown in Figure 1, comprise one section of general single mode fiber 1, wherein write long period fiber grating A2 and long period fiber grating B3, the cladding surface of long period fiber grating B3 place optical fiber is coated with layer of metal film 4; Utilize pumping that laser is injected to long period fiber grating A2, pump light is coupled in fibre cladding, and at covering and the metallic film 4 of long period fiber grating B3, heat interchange occurs, and affects heat field and distributes, measure it by long period fiber grating B3 simultaneously and change, reach the object of flow sensing.
The basic functional principle of the optic flow sensor based on metal-coated membrane long period fiber grating:
As shown in Figure 1, on the one hand, laser is injected by the free end of long period fiber grating A section optical fiber, and when through long period fiber grating A, most energy of laser will go in will being coupled to fibre cladding, thereby cause metal film absorption portion laser energy.Absorb the metal film of laser energy by releases heat, forced corresponding grating region to form specific temperature field.Obviously, rate of flow of fluid is larger, and the heat of taking away is just larger, and the temperature of grating region is just less, and temperature becomes negative linear relationship with fluid flow.The susceptibility of long-period grating pair temperature is five times of ordinary optic fibre grating, therefore the variation of measuring metal film temperature field by long period fiber grating B can obtain very high sensitivity, and then obtains fluid flow data more accurately.
As shown in Figure 1, wherein: single-mode fiber 1 overall length 11cm, long period fiber grating A2 length is 25mm, long period fiber grating A2 is apart from left end free end 20mm, with long period fiber grating B3 distance be 20mm; Long period fiber grating B3 length is 25mm, and apart from right-hand member free end 20mm, metal film length is 30mm;
As shown in Figure 2, wideband light source 5 is the ASE light source of bandwidth 1520-1620nm; Pump laser 6 is continuous Raman fiber laser, and power 0-1W is adjustable; Wavelength division multiplexer 7 is high power wavelength division multiplexer, takes wave band and can determine according to the centre wavelength of long period fiber grating A2; Spectroanalysis instrument 9 is AQ8683.
The pick-up unit of the novel Hot Wire Type Flow Sensor part based on fiber grating has many structures, enumerates a kind of detection architecture below, but is not limited only to this.
As shown in Figure 2, adopt the first structure, wavelength division multiplexer 6 is connected sensing unit 8 with wideband light source 5 and pump laser 6, and the other end of sensing unit 8 connects spectroanalysis instrument 9.
Claims (3)
1. the optic flow sensor based on metal-coated membrane long period fiber grating, comprises layer of metal film (4), wideband light source (5), pump laser (6), wavelength division multiplexer (7), sensing unit (8) and spectroanalysis instrument (9) that one section of general single mode fiber (1), long period fiber grating A (2), long period fiber grating B (3), cladding surface plate.It is characterized in that: sensing unit (8) comprises the single-mode fiber (1) that is carved with long period fiber grating A (2), long period fiber grating B (3) and cladding surface thereof and is coated with metallic film (4).Wavelength division multiplexer (6) is connected sensing unit (8) with wideband light source (5) and pump laser (6), the other end of sensing unit (8) connects spectroanalysis instrument (9).
2. long period fiber grating A as claimed in claim 1 (2), is characterized in that: the pumping laser of specific wavelength can be coupled in covering.
3. metallic film as claimed in claim 1 (4), is characterized in that: can absorb energy the evolution of heat of the laser that is coupled into covering.
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| CN201410076437.3A CN103791957A (en) | 2014-03-03 | 2014-03-03 | Fiber flow sensor based on metal-film-coated and long-period fiber bragg gratings |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104864895A (en) * | 2015-04-30 | 2015-08-26 | 天津大学 | Method for measuring little-mode long-period fiber grating based on carbon nanomaterial and sensor thereof |
| CN105973279A (en) * | 2016-06-03 | 2016-09-28 | 安徽工业大学 | Single-end reflective long-period fiber grating sensor and manufacture process thereof |
| CN107870039A (en) * | 2016-09-27 | 2018-04-03 | 福州高意通讯有限公司 | A kind of Fourier transform spectrometer |
| US10012776B2 (en) | 2015-11-23 | 2018-07-03 | Microsoft Technology Licensing, Llc | Optical filters, methods of manufacture, and methods of use |
| CN108414036A (en) * | 2018-03-19 | 2018-08-17 | 山东省科学院激光研究所 | A kind of quasi-distributed flow rate monitoring system |
| CN110579249A (en) * | 2019-09-17 | 2019-12-17 | 西北大学 | Co-doped multimode fiber bragg grating based hot-wire flow sensor and manufacturing method thereof |
| CN115343806A (en) * | 2022-06-15 | 2022-11-15 | 暨南大学 | Multi-wavelength high-order mode generation method based on cascade long-period fiber grating |
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Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104864895A (en) * | 2015-04-30 | 2015-08-26 | 天津大学 | Method for measuring little-mode long-period fiber grating based on carbon nanomaterial and sensor thereof |
| CN104864895B (en) * | 2015-04-30 | 2017-04-05 | 天津大学 | Measuring method and sensor based on the few mould LPFG of carbon nanomaterial |
| US10012776B2 (en) | 2015-11-23 | 2018-07-03 | Microsoft Technology Licensing, Llc | Optical filters, methods of manufacture, and methods of use |
| CN105973279A (en) * | 2016-06-03 | 2016-09-28 | 安徽工业大学 | Single-end reflective long-period fiber grating sensor and manufacture process thereof |
| CN107870039A (en) * | 2016-09-27 | 2018-04-03 | 福州高意通讯有限公司 | A kind of Fourier transform spectrometer |
| CN108414036A (en) * | 2018-03-19 | 2018-08-17 | 山东省科学院激光研究所 | A kind of quasi-distributed flow rate monitoring system |
| CN108414036B (en) * | 2018-03-19 | 2021-03-09 | 山东省科学院激光研究所 | Quasi-distributed flow velocity monitoring system |
| CN110579249A (en) * | 2019-09-17 | 2019-12-17 | 西北大学 | Co-doped multimode fiber bragg grating based hot-wire flow sensor and manufacturing method thereof |
| CN110579249B (en) * | 2019-09-17 | 2021-06-29 | 西北大学 | Hot-wire flow sensor based on cobalt-doped multimode fiber bragg grating and manufacturing method |
| CN115343806A (en) * | 2022-06-15 | 2022-11-15 | 暨南大学 | Multi-wavelength high-order mode generation method based on cascade long-period fiber grating |
| CN115343806B (en) * | 2022-06-15 | 2023-07-25 | 暨南大学 | Multi-wavelength high-order mode generation method based on cascade long-period fiber bragg grating |
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Application publication date: 20140514 |