CN103278214B - Polarization maintaining fiber bragg grating liquid level sensor - Google Patents
Polarization maintaining fiber bragg grating liquid level sensor Download PDFInfo
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- CN103278214B CN103278214B CN201310206911.5A CN201310206911A CN103278214B CN 103278214 B CN103278214 B CN 103278214B CN 201310206911 A CN201310206911 A CN 201310206911A CN 103278214 B CN103278214 B CN 103278214B
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Abstract
A kind of polarization maintaining fiber bragg grating liquid level sensor, the drive link being processed with tooth bar is set at buoy, drive link is arranged on crossbeam, crossbeam is arranged cogged steel pipe is installed, gear engages with the tooth bar on drive link top, be provided with bearing between steel pipe and gear, the end of steel pipe is provided with fixed head, is provided with polarization maintaining fiber bragg grating in steel pipe.The liquid level sensor of this structure is compared with existing Fiber Grating Liquid Depth Sensor, and sensitivity reaches 0.03dB/cm, to liquid level change response in well repeated.The present invention has the advantages such as structure is simple, measurement range is large, practical, can be used for the liquid level sensor measuring the liquid level height such as water, gasoline, kerosene.
Description
Technical field
The invention belongs to Fiber Grating Sensors Technology field, be specifically related to the liquid level sensor measuring liquid level.
Background technology
Liquid level sensor is used to the surveying instrument of tracer liquid height, has important application in many aspects, as fuel storage system, and water level monitoring and some chemical reaction process monitorings etc.At present, the liquid level sensor based on Fibre Optical Sensor principle is Mach-Zahnder interference formula sensor, Fiber Bragg Grating FBG (FBG) formula sensor, long-period fiber grating (LPG) formula sensor, distributed fiber grating laser instrument, multiple-mode interfence formula sensor mostly.Find in the process of research and development: long-period fiber grating formula and Mach-Zahnder interference formula liquid level sensor are generally transmission-type structure, and degree of being practical is lower, and the complex manufacturing process of long-period fiber grating, production cost are high; Although Fiber Bragg Grating FBG formula sensor stability is better, but for corroding Fiber Bragg Grating FBG during level gauging, reduce the physical strength of sensor, or utilize mechanical strain structure that liquid level change is converted into the wave length shift of Fiber Bragg Grating FBG, this sensor, measurement range is little, Temperature cross-over is highly sensitive.Compare with fiber Bragg grating sensor, distributed fiber grating laser instrument can improve level gauging scope and eliminate Temperature cross-over sensitivity, but distributed fiber grating Optical Maser System is complicated, and integration degree is low; The multimode interferometric structure of coreless fiber is simple, but light loss is larger.Therefore, the demand meeting application is all difficult to.
The basic sensing principle of polarization maintaining fiber bragg grating liquid level sensor utilizes gearing to change the power of vertical direction into torsion to polarization maintaining fiber bragg grating, namely liquid level variable quantity is converted to the torsional capacity of polarization maintaining fiber bragg grating.When polarization maintaining fiber bragg grating twists, the polarisation of light state of its internal transmission changes, cause the energy of the centre wavelength of its reflectance spectrum to change, therefore, the change of liquid level can be measured by the change of monitoring polarization maintaining fiber bragg grating energy.Also do not find polarization maintaining fiber bragg grating liquid level sensor at present.
Summary of the invention
Technical matters to be solved by this invention is the shortcoming overcoming above-mentioned fibre optic liquid level sensor, provides a kind of reasonable in design, structure is simple, measurement range is large, practical polarization maintaining fiber bragg grating liquid level sensor.
Solving the problems of the technologies described above adopted technical scheme is: arrange the drive link being processed with tooth bar at buoy, drive link is arranged on crossbeam, crossbeam is arranged cogged steel pipe is installed, gear engages with the tooth bar on drive link top, bearing is provided with between steel pipe and gear, the end of steel pipe is provided with fixed head, is provided with polarization maintaining fiber bragg grating in steel pipe.
Polarization maintaining fiber bragg grating of the present invention is: inscribing on polarization maintaining optical fibre has grating, and a reflection wavelength of grating is 1520 ~ 1620nm, and the difference of another reflection wavelength of grating and a reflection wavelength is 0 ~ 1nm.
Polarization maintaining fiber bragg grating of the present invention is: inscribing on polarization maintaining optical fibre has grating, and reflection wavelength the best for grating is 1570nm, and difference the best of another reflection wavelength of grating and a reflection wavelength is 0.5nm.
The present invention adopts the Bragg grating inscribed on bow-tie type polarization maintaining optical fibre, the high birefringence caused because polarization maintaining optical fibre internal stress distribution is unbalance, reflectance spectrum is caused to there will be two resonant wavelengths, these two resonant wavelengths represent two mutually perpendicular polarization modes respectively, torsional moment is coupled between cause polarization maintaining fiber bragg grating to reflect two inclined moulds, show as the change of two resonant wavelength energy of reflectance spectrum, and wavelength remains unchanged substantially.Polarization maintaining fiber bragg grating is encapsulated in torsion device, then gearing is utilized to change the power of vertical direction into torsion to polarization maintaining fiber bragg grating, namely liquid level variable quantity is converted to the torsional capacity of polarization maintaining fiber bragg grating, is measured the change of liquid level by the change of monitoring polarization maintaining fiber bragg grating reflectance spectrum resonant wavelength energy.The liquid level sensor of this structure is compared with existing Fiber Grating Liquid Depth Sensor, and sensitivity reaches 0.03dB/cm, to liquid level change response in well repeated.The present invention has the advantages such as structure is simple, measurement range is large, practical, can be used for the liquid level sensor measuring the liquid level height such as water, gasoline, kerosene.
Accompanying drawing explanation
Fig. 1 is the structural representation of an invention embodiment.
Embodiment
Below in conjunction with drawings and Examples, the present invention is described in more detail, but the invention is not restricted to these embodiments.
Embodiment 1
In FIG, the polarization maintaining fiber bragg grating liquid level sensor of the present embodiment is made up of steel pipe 1, polarization maintaining fiber bragg grating 2, gear 3, drive link 4, bearing 5, fixed head 6, buoy 7, crossbeam 8 connection.
Drive link 4 is had by thread connection in the center of buoy 7, the top of drive link 4 is processed with tooth bar, drive link 4 is arranged on crossbeam 8, drive link 4 can move up and down on crossbeam 8, the center of gear 3 is provided with steel pipe 1, bearing 5 is installed between steel pipe 1 and gear, steel pipe 1 screw threads for fastening connector is fixedly connected on crossbeam 8, gear 3 engages with the tooth bar on drive link 4 top; buoy 7 fluctuates on liquid level; drive link 4 moves up and down, and drive link 4 driven gear 3 rotates, and steel pipe 1 does not rotate.Have fixed head 6 at the right-hand member of steel pipe 1 by thread connection, fixed head 6 is circular slab, also can be processed into rectangular slab, fixed head 6 is processed porose, is arranged on the equipment needing to survey liquid level for being fixedly connected by the present invention's screw threads for fastening connector.In steel pipe, be provided with polarization maintaining fiber bragg grating 2, the polarization maintaining fiber bragg grating 2 of the present embodiment is that carving and writing method inscription has grating to make routinely on polarization maintaining optical fibre, and a reflection wavelength of grating is 1570nm, and another reflection wavelength is 1570.5nm.This polarization maintaining fiber bragg grating 2 changes along with the liquid level of fluid to be measured, its reflectance spectrum wavelength energy changes, adopt spectroanalysis instrument to measure polarization maintaining fiber bragg grating liquid level sensor reflectance spectrum wavelength energy with the variable quantity that night rises in position, the liquid level of fluid to be measured can be calculated.The liquid level of fluid to be measured calculates by following formula:
y＝0.0592×sin((x-5.20364)π/5.66788)-7.02186
In formula, y is reflectance spectrum wavelength energy, and unit is dB, x is liquid level.
Embodiment 2
In the present embodiment, be provided with polarization maintaining fiber bragg grating 2 in steel pipe 1, on the present embodiment polarization maintaining optical fibre, carving and writing method inscription has grating routinely, and a reflection wavelength of grating is 1520nm, and another reflection wavelength is 1520.5nm.The connecting relation of other parts and parts is identical with embodiment 1.
Embodiment 3
In the present embodiment, be provided with polarization maintaining fiber bragg grating 2 in steel pipe 1, on the present embodiment polarization maintaining optical fibre, carving and writing method inscription has grating routinely, and a reflection wavelength of grating is 1620nm, and another reflection wavelength is 1620.5nm.The connecting relation of other parts and parts is identical with embodiment 1.
Embodiment 4
In above embodiment 1 ~ 3, polarization maintaining fiber bragg grating 2 is installed in steel pipe 1, on polarization maintaining optical fibre, carving and writing method inscription has grating routinely, a reflection wavelength of grating is identical with corresponding embodiment, another reflection wavelength is equal with a reflection wavelength, and namely the difference of a reflection wavelength and another reflection wavelength is 0.The connecting relation of other parts and parts is identical with embodiment 1.
Embodiment 5
In above embodiment 1 ~ 3, polarization maintaining fiber bragg grating 2 is installed in steel pipe 1, on polarization maintaining optical fibre, carving and writing method inscription has grating routinely, and a reflection wavelength of grating is identical with corresponding embodiment, and a reflection wavelength of grating and the difference of another reflection wavelength are 1nm.The connecting relation of other parts and parts is identical with embodiment 1.
In order to verify beneficial effect of the present invention, inventor adopts the polarization maintaining fiber bragg grating liquid level sensor of the embodiment of the present invention 1 to carry out laboratory study test, and test situation is as follows:
Experimental apparatus: wideband light source, model is ASE-CL-N, is produced by China's great source photoelectricity; Spectroanalysis instrument, model is AQ6370B, is produced by Japanese Agilent company.
1, the liquid level of test water
The liquid level of polarization maintaining fiber bragg grating liquid level sensor to water of example 1 is adopted to test.In measuring process, in water vat, add water, polarization maintaining fiber bragg grating liquid level sensor is put into water vat; buoy 7 swims on the water surface; fixed head 6 is fixed on water vat wall, add 19 water in water vat, water level rises 0 ~ 19cm; often add a water; water level often rises 1cm, measures a polarization maintaining fiber bragg grating liquid level sensor reflectance spectrum wavelength energy, and test water level rises the situation of 0 ~ 19cm; carry out matching with Origin software, the fit correlation of correspondence is:
y＝0.0592×sin((x-5.20364)π/5.66788)-7.02186
In formula, y is reflectance spectrum wavelength energy, unit is dB, x is liquid level, adopts the change that spectroanalysis instrument measurement polarization maintaining fiber bragg grating liquid level sensor reflectance spectrum wavelength energy rises with water level, liquid level Sensitivity, the Repeatability of inspection polarization maintaining fiber bragg grating liquid level sensor.Experimental result is in table 1.
The change of table 1 reflectance spectrum wavelength energy and the relation of liquid level
| Liquid level (mm) | Reflectance spectrum wavelength energy (dB) |
| 1 | -7.09 |
| 2 | -7.085 |
| 3 | -7.08 |
| 4 | -7.075 |
| 5 | -7.06 |
| 6 | -7.04 |
| 7 | -7.03 |
| 8 | -7 |
| 9 | -6.97 |
| 10 | -6.94 |
| 11 | -6.98 |
| 12 | -7.01 |
| 13 | -7.06 |
| 14 | -7.07 |
| 15 | -7.06 |
| 16 | -7.05 |
| 17 | -7.03 |
| 18 | -6.99 |
| 19 | -6.95 |
From table 1, along with liquid level rises, the energy of reflectance spectrum wavelength reduces in cyclical variation, and liquid level rises within the scope of 0 ~ 19cm, and the maximum level sensitivity of sensor is 0.03dB/cm.Through many experiments, sensor is well repeated to the response that liquid level changes.
Claims (2)
1. a polarization maintaining fiber bragg grating liquid level sensor, the drive link (4) being processed with tooth bar is set at buoy (7), drive link (4) is arranged on crossbeam (8), the upper setting of crossbeam (8) is provided with the steel pipe (1) of gear (3), gear (3) engages with the tooth bar on drive link (4) top, bearing (5) is provided with between steel pipe (1) and gear (3), the end of steel pipe (1) is provided with fixed head (6), it is characterized in that: in steel pipe (1), be provided with polarization maintaining fiber bragg grating (2), described polarization maintaining fiber bragg grating (2) is: inscribing on polarization maintaining optical fibre has grating, and a reflection wavelength of grating is 1520 ~ 1620nm, and the difference of another reflection wavelength of grating and a reflection wavelength is 0 ~ 1nm.
2. polarization maintaining fiber bragg grating liquid level sensor according to claim 1, it is characterized in that: described polarization maintaining fiber bragg grating (2) is: inscribing on polarization maintaining optical fibre has grating, a reflection wavelength of grating is 1570nm, and the difference of another reflection wavelength of grating and a reflection wavelength is 0.5nm.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109655133A (en) * | 2018-12-27 | 2019-04-19 | 北京信息科技大学 | Liquid level sensor and preparation method thereof based on single mode FBG grating |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN111103029B (en) * | 2019-12-26 | 2021-04-30 | 河南理工大学 | Intelligent monitoring device and monitoring method for fiber bragg grating of coal level of coal bunker |
| CN112857530B (en) * | 2021-03-17 | 2024-06-18 | 承德热河克罗尼仪表有限公司 | Electric pontoon liquid level meter measuring device and have this measuring device's electric pontoon liquid level meter |
Citations (4)
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|---|---|---|---|---|
| CN2414401Y (en) * | 2000-03-15 | 2001-01-10 | 廖文山 | Liquid level automatic controller for storage tank |
| JP2001188021A (en) * | 1999-10-22 | 2001-07-10 | Fuji Electric Co Ltd | Optical water level detector |
| CN101832808A (en) * | 2010-04-15 | 2010-09-15 | 北京交通大学 | Taper chirped fiber grating liquid level sensor based on reflection spectrum bandwidth detection |
| KR20130049615A (en) * | 2011-11-04 | 2013-05-14 | 한국광기술원 | Temperature-compensated flow rate measuring apparatus based on fiber bragg grating sensors |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001188021A (en) * | 1999-10-22 | 2001-07-10 | Fuji Electric Co Ltd | Optical water level detector |
| CN2414401Y (en) * | 2000-03-15 | 2001-01-10 | 廖文山 | Liquid level automatic controller for storage tank |
| CN101832808A (en) * | 2010-04-15 | 2010-09-15 | 北京交通大学 | Taper chirped fiber grating liquid level sensor based on reflection spectrum bandwidth detection |
| KR20130049615A (en) * | 2011-11-04 | 2013-05-14 | 한국광기술원 | Temperature-compensated flow rate measuring apparatus based on fiber bragg grating sensors |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109655133A (en) * | 2018-12-27 | 2019-04-19 | 北京信息科技大学 | Liquid level sensor and preparation method thereof based on single mode FBG grating |
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