CN110864762A - Input type optical fiber liquid level instrument without installation - Google Patents
Input type optical fiber liquid level instrument without installation Download PDFInfo
- Publication number
- CN110864762A CN110864762A CN201911227307.4A CN201911227307A CN110864762A CN 110864762 A CN110864762 A CN 110864762A CN 201911227307 A CN201911227307 A CN 201911227307A CN 110864762 A CN110864762 A CN 110864762A
- Authority
- CN
- China
- Prior art keywords
- optical fiber
- liquid level
- sensing module
- fiber
- spectrum
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/14—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measurement of pressure
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Levels Of Liquids Or Fluent Solid Materials (AREA)
Abstract
The invention discloses a drop-in optical fiber liquid level meter without installation.A wide-spectrum light source is connected to one input end of an optical fiber coupler; the other input end of the optical fiber coupler is connected to the spectrum analyzer; one output port of the optical fiber coupler is connected to a section of common single-mode optical fiber with a flattened end face through a polarization controller; and the other output port of the optical fiber coupler is connected to the optical fiber liquid level meter sensing module. A section of polarization maintaining photonic crystal fiber is connected in a sensing arm of the Michelson interferometer to form a composite interferometer structure, and then the liquid level information detected by a sensing module of the fiber level gauge can be obtained by monitoring the contrast of a composite interference spectrum envelope spectral line at a certain wavelength and demodulating the contrast. The optical fiber liquid level meter does not need to be installed, can be directly thrown into liquid, and is simple and reliable in detection. In addition, compared with the traditional wavelength demodulation method, the method for demodulating the contrast of the spectrum of the composite interferometer at a specific wavelength greatly improves the measurement precision and is more accurate in detection.
Description
Technical Field
The invention belongs to the technical field of optical fiber liquid level sensing, and particularly relates to a drop-in optical fiber liquid level meter without installation.
Background
The accurate optical fiber liquid level measurement has wide application in industrial production and many aspects of people's life, and has very important significance.
Optical fiber liquid level sensors have been widely focused and studied because of their advantages of sensitivity, reliability, flexible form, etc. The most studied of these types belongs to the multimode interference or MZ interference type, for example Xiaodong Wen et al in 2013 propose MZI structures formed by two up-taps for level measurement, achieving level sensing with a sensitivity of up to 22.5nm/m in the 14.3cm range. However, such a structure is susceptible to interference from factors such as ambient temperature and refractive index. In order to make the sensor more stable, Shuhui Liu et al in 2016 proposed a liquid level meter based on an anti-resonance structure of a hollow glass tube. The sensitivity of the sensor is as high as 0.4dB/mm, and the sensor is insensitive to the interference of external temperature, refractive index and the like. But its extremely small measuring range (only 18mm) is not negligible. In order to further improve the performance, YU WANG et al propose a hollow bragg fiber liquid level sensor in 2018, which realizes optical fiber liquid level measurement with high sensitivity of 1.1dB/mm and fast reaction time, but also has the defect of too small measurement range. In addition, many of the above fluid level sensors typically require a fixed mounting of the sensing structure in the probing environment, which further increases system cost and complexity.
Disclosure of Invention
The invention aims to solve the technical problem of providing the drop-in optical fiber liquid level instrument without installation, and the technical effects of high precision and large dynamic range of liquid level signals, direct drop-in of a sensing structure and no installation are realized.
The technical scheme adopted by the invention for solving the technical problems is as follows: the drop-in optical fiber liquid level instrument without installation is provided, and comprises at least one optical fiber coupler and an optical fiber liquid level instrument sensing module, wherein a light source is connected to one input end of the optical fiber coupler; the other input end of the optical fiber coupler is connected to the spectrum analyzer; one output port of the optical fiber coupler is connected to a section of single-mode optical fiber through the polarization controller; and the other output port of the optical fiber coupler is connected to the optical fiber liquid level meter sensing module.
According to above-mentioned technical scheme, optic fibre liquid level appearance sensing module includes: the single-mode fiber is welded with a section of polarization-maintaining photonic crystal fiber; the polarization-maintaining photonic crystal fiber is wound into a spiral plane and embedded into the upper square silica gel sheet and the lower square silica gel sheet; the peripheral gap between the upper square silica gel sheet and the lower square silica gel sheet is sealed; the optical fiber liquid level instrument sensing module senses the external liquid pressure and obtains liquid level information according to the liquid pressure.
According to the technical scheme, the side length of the square silica gel sheet is 8 cm-10 cm, and the thickness of the square silica gel sheet is 0.5 mm-1 mm.
According to the technical scheme, the connected light path structure is a composite interferometer structure formed by connecting a section of polarization-maintaining photonic crystal fiber in a sensing arm of a Michelson interferometer; the composite spectrum of the composite interferometer presents a fine spectrum caused by Michelson interference arm length difference and an envelope spectrum caused by the birefringence of the polarization-maintaining photonic crystal fiber; when the polarization maintaining photonic crystal fiber in the fiber level gauge sensing module is under the action of liquid pressure, the envelope spectral line of the composite interference spectrum drifts; the liquid level information detected by the optical fiber liquid level instrument sensing module is obtained by monitoring the contrast demodulation of the composite interference spectrum envelope spectral line at a certain wavelength.
According to the technical scheme, the optical fiber coupler is a 3dB coupler, and the coupling ratio is 50: 50.
According to the technical scheme, the polarization-maintaining photonic crystal fiber is provided with 10-4The large birefringence of magnitude is 4 cm-8 cm in length.
According to the technical scheme, the arm length difference between the sensing arm and the reference arm is 3-4 mm.
According to the technical scheme, the whole density of the sensing module of the optical fiber liquid level meter is larger than that of liquid, and the sensing module can automatically sink to the bottom of the liquid after the liquid is put into the sensing module.
The invention has the following beneficial effects: a light path structure is designed, and a section of polarization-maintaining photonic crystal fiber is embedded into a sensing arm of a Michelson interferometer to form a composite interferometer structure. The composite spectrum of the composite interferometer presents a fine spectrum caused by Michelson interference arm length difference and an envelope spectrum caused by the birefringence of the polarization-maintaining photonic crystal fiber; when the photonic crystal fiber in the fiber level sensor sensing module is under the action of liquid pressure, the envelope spectral line of the composite interference spectrum can drift; the liquid pressure information detected by the optical fiber liquid level instrument sensing module can be obtained by demodulating through monitoring the contrast of the composite interference spectrum envelope spectral line at a certain wavelength. The polarization maintaining photonic crystal fiber in the sensing module of the fiber level meter is wound into a spiral plane and embedded into the upper square silica gel sheet and the lower square silica gel sheet, and the peripheral gap between the upper square silica gel sheet and the lower square silica gel sheet is sealed by glue. Because the whole density of the sensing module of the optical fiber liquid level meter is greater than that of liquid, the sensing module of the optical fiber liquid level meter can automatically sink to the bottom of the liquid after the liquid is put into the sensing module, and the liquid level information is reflected by the liquid pressure detected by the sensing module of the optical fiber liquid level meter. The optical fiber liquid level meter does not need to be installed, can be directly thrown into liquid, and is simple and reliable in detection. In addition, compared with the traditional wavelength demodulation method, the method for demodulating the contrast of the spectrum of the composite interferometer at a specific wavelength greatly improves the measurement precision and is more accurate in detection.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic diagram of a drop-in optical fiber level gauge without installation according to an embodiment of the present invention;
FIG. 2 is an internal structure diagram of a sensing module of the optical fiber liquid level meter according to the embodiment of the invention;
wherein: 1-wide spectrum light source, 2-spectrum analyzer, 3-optical fiber coupler, 4-polarization controller, 5-optical fiber liquid level meter sensing module, 6-liquid, 7-container, 8-common single mode fiber, 9-polarization maintaining photonic crystal fiber, 10-upper square silica gel sheet, 11-lower square silica gel sheet and 12-glue.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
As shown in fig. 1 and 2, the drop-in optical fiber liquid level meter installed in the embodiment of the invention realizes the measurement of liquid level information, and the sensor is directly dropped without installation and has high measurement precision.
According to the input type optical fiber liquid level instrument, a section of polarization-maintaining photonic crystal fiber is embedded into a sensing arm of a Michelson interferometer to form a composite interferometer structure, and a composite spectrum of the composite interferometer can present a fine spectrum caused by the length difference of the Michelson interferometer arm and an envelope spectrum caused by the birefringence of the polarization-maintaining photonic crystal fiber; when the photonic crystal fiber in the fiber level sensor sensing module is under the action of liquid pressure, the envelope spectral line of the composite interference spectrum can drift; the liquid pressure information detected by the optical fiber liquid level instrument sensing module can be obtained by demodulating through monitoring the contrast of the composite interference spectrum envelope spectral line at a certain wavelength. The polarization maintaining photonic crystal fiber in the sensing module of the fiber level meter is wound into a spiral plane and embedded into the upper square silica gel sheet and the lower square silica gel sheet, and the peripheral gap between the upper square silica gel sheet and the lower square silica gel sheet is sealed by glue. Because the whole density of the sensing module of the optical fiber liquid level meter is greater than that of liquid, the sensing module of the optical fiber liquid level meter can automatically sink to the bottom of the liquid after the liquid is put into the sensing module, and the liquid level information is reflected by the liquid pressure detected by the sensing module of the optical fiber liquid level meter. The optical fiber liquid level meter does not need to be installed, can be directly thrown into liquid, and is simple and reliable in detection. In addition, compared with the traditional wavelength demodulation method, the contrast demodulation method of the spectrum of the composite interferometer at a specific wavelength is utilized, so that the measurement precision is greatly improved, and the detection is more accurate.
Referring specifically to fig. 1, the drop-in optical fiber level gauge of claim 1 of the present invention, which does not require installation, comprises: the broad spectrum light source 1 is connected to one input end of the optical fiber coupler 3; the other input end of the optical fiber coupler 3 is connected to the optical spectrum analyzer 2; one output port of the optical fiber coupler 3 is connected to a section of common single-mode optical fiber with a flattened end face through a polarization controller 4; the other output port of the optical fiber coupler 3 is connected to the optical fiber liquid level instrument sensing module 5; the fiber optic level gauge sensing module 5 is placed into a container 7 containing liquid 6.
Referring to fig. 2, the structure of the fiber optic level sensor module 5 is illustrated, which at least includes: a common single-mode fiber 8 is welded with a polarization-maintaining photonic crystal fiber 9 with a flattened end face; the polarization-maintaining photonic crystal fiber 9 is wound into a spiral plane and is embedded into the upper square silica gel sheet 10 and the lower square silica gel sheet 11; the peripheral gap between the upper square silicon sheet 10 and the lower square silicon sheet 11 is sealed by glue 12; the optical fiber liquid level instrument sensing module 5 can directly sense the external liquid pressure, and the liquid pressure reflects the liquid level information.
In this embodiment, the drop-in optical fiber liquid level meter achieves the following effects:
1. a light path structure is designed, and a section of polarization-maintaining photonic crystal fiber is embedded into a sensing arm of a Michelson interferometer to form a composite interferometer structure. The composite spectrum of the composite interferometer presents a fine spectrum caused by Michelson interference arm length difference and an envelope spectrum caused by the birefringence of the polarization-maintaining photonic crystal fiber; when the photonic crystal fiber in the fiber level sensor sensing module is under the action of liquid pressure, the envelope spectral line of the composite interference spectrum can drift; the liquid pressure information detected by the optical fiber liquid level instrument sensing module can be obtained by demodulating through monitoring the contrast of the composite interference spectrum envelope spectral line at a certain wavelength, and the liquid level information is directly reflected by the liquid pressure. Thus, the optical fiber liquid level meter of the embodiment of the invention is realized.
2. The sensing element in the embodiment of the invention is an optical fiber liquid level instrument sensing module, a polarization maintaining photonic crystal optical fiber is wound into a spiral plane and is embedded into an upper square silica gel sheet and a lower square silica gel sheet to form the sensing element, and the peripheral gap between the upper square silica gel sheet and the lower square silica gel sheet is sealed by glue. Because the whole density of the sensing module of the optical fiber liquid level meter is greater than that of liquid, the sensing module of the optical fiber liquid level meter can automatically sink to the bottom of the liquid after the liquid is put into the sensing module, and the liquid level information is reflected by the liquid pressure detected by the sensing module of the optical fiber liquid level meter. The optical fiber liquid level meter in the embodiment is directly thrown into liquid without installation when detecting the liquid level, and the method is simple and reliable.
3. In the embodiment of the invention, the signal demodulation of the optical fiber liquid level meter is realized by using a contrast demodulation method of a composite interferometer spectrum at a specific wavelength, and compared with the traditional wavelength demodulation method, the method has the advantages that the measurement precision is greatly improved, and the detection is more accurate.
It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.
Claims (8)
1. An input type optical fiber liquid level instrument without installation is characterized by comprising at least one optical fiber coupler and an optical fiber liquid level instrument sensing module, wherein a light source is connected to one input end of the optical fiber coupler; the other input end of the optical fiber coupler is connected to the spectrum analyzer; one output port of the optical fiber coupler is connected to a section of single-mode optical fiber through the polarization controller; and the other output port of the optical fiber coupler is connected to the optical fiber liquid level meter sensing module.
2. The unmounted immersion fiber optic liquid level gauge according to claim 1, wherein the fiber optic liquid level gauge sensing module comprises: the single-mode fiber is welded with a section of polarization-maintaining photonic crystal fiber; the polarization-maintaining photonic crystal fiber is wound into a spiral plane and embedded into the upper square silica gel sheet and the lower square silica gel sheet; the peripheral gap between the upper square silica gel sheet and the lower square silica gel sheet is sealed; the optical fiber liquid level instrument sensing module senses the external liquid pressure and obtains liquid level information according to the liquid pressure.
3. The drop-in optical fiber liquid level instrument without installation according to claim 1 or 2, wherein the square silica gel sheet has a side length of 8cm to 10cm and a thickness of 0.5mm to 1 mm.
4. The drop-in optical fiber liquid level instrument without installation according to claim 1 or 2, wherein the connected optical path structure is a composite interferometer structure formed by connecting a section of polarization-maintaining photonic crystal fiber in a sensing arm of a Michelson interferometer; the composite spectrum of the composite interferometer presents a fine spectrum caused by Michelson interference arm length difference and an envelope spectrum caused by the birefringence of the polarization-maintaining photonic crystal fiber; when the polarization maintaining photonic crystal fiber in the fiber level gauge sensing module is under the action of liquid pressure, the envelope spectral line of the composite interference spectrum drifts; the liquid level information detected by the optical fiber liquid level instrument sensing module is obtained by monitoring the contrast demodulation of the composite interference spectrum envelope spectral line at a certain wavelength.
5. The unmounted drop-in fiber optic liquid level gauge according to claim 1 or 2, wherein the fiber optic coupler is a 3dB coupler with a coupling ratio of 50: 50.
6. The unmounted immersion fiber optic liquid level gauge according to claim 1 or 2, wherein the polarization maintaining photonic crystal fiber has 10-4The large birefringence of magnitude is 4 cm-8 cm in length.
7. The unmounted immersion fiber optic liquid level gauge according to claim 4, wherein the difference in arm length between the sensing arm and the reference arm is 3mm to 4 mm.
8. The non-installed drop-in type optical fiber liquid level instrument according to claim 1 or 2, wherein the overall density of the sensing module of the optical fiber liquid level instrument is greater than that of liquid, and the sensing module of the optical fiber liquid level instrument can automatically sink to the bottom of the liquid after the liquid is dropped.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911227307.4A CN110864762A (en) | 2019-12-04 | 2019-12-04 | Input type optical fiber liquid level instrument without installation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911227307.4A CN110864762A (en) | 2019-12-04 | 2019-12-04 | Input type optical fiber liquid level instrument without installation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN110864762A true CN110864762A (en) | 2020-03-06 |
Family
ID=69658422
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911227307.4A Pending CN110864762A (en) | 2019-12-04 | 2019-12-04 | Input type optical fiber liquid level instrument without installation |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110864762A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111458668A (en) * | 2020-06-02 | 2020-07-28 | 黑龙江大学 | Vector magnetic field sensor and method for detecting magnetic field by using same |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101929879A (en) * | 2010-08-02 | 2010-12-29 | 北京航空航天大学 | Optical fiber sensor for simultaneously sensing temperature and pressure |
| CN101957227A (en) * | 2010-10-22 | 2011-01-26 | 南京信息工程大学 | Photonic crystal fiber optic liquid level sensor and sensing system formed by same |
| US20130070235A1 (en) * | 2011-09-20 | 2013-03-21 | Yuehua Chen | Multiple spectrum channel, multiple sensor fiber optic monitoring system |
| CN103471761A (en) * | 2013-09-22 | 2013-12-25 | 中国工程物理研究院总体工程研究所 | Micro-gap interlayer photonic crystal fiber pressure sensor in pre-tightening combined structure |
| CN105021180A (en) * | 2015-07-30 | 2015-11-04 | 哈尔滨工程大学 | Optical fiber gyroscope with optical fiber ring adopting double-ring design |
| CN105758567A (en) * | 2016-04-21 | 2016-07-13 | 吉林大学 | Fiber interference type pressure sensor based on 3*3 coupler |
| CN105841724A (en) * | 2016-03-24 | 2016-08-10 | 北京理工大学 | Interference type optical fiber sensor for simultaneously measuring pressure and temperature |
| CN106610309A (en) * | 2016-12-27 | 2017-05-03 | 天津市欧斯曼科技有限公司 | A device measuring a liquid level by using the Mach-Zehnder interference technology |
| CN110260947A (en) * | 2019-07-30 | 2019-09-20 | 南昌航空大学 | A kind of fibre optic liquid level sensor and method for sensing |
-
2019
- 2019-12-04 CN CN201911227307.4A patent/CN110864762A/en active Pending
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101929879A (en) * | 2010-08-02 | 2010-12-29 | 北京航空航天大学 | Optical fiber sensor for simultaneously sensing temperature and pressure |
| CN101957227A (en) * | 2010-10-22 | 2011-01-26 | 南京信息工程大学 | Photonic crystal fiber optic liquid level sensor and sensing system formed by same |
| US20130070235A1 (en) * | 2011-09-20 | 2013-03-21 | Yuehua Chen | Multiple spectrum channel, multiple sensor fiber optic monitoring system |
| CN103471761A (en) * | 2013-09-22 | 2013-12-25 | 中国工程物理研究院总体工程研究所 | Micro-gap interlayer photonic crystal fiber pressure sensor in pre-tightening combined structure |
| CN105021180A (en) * | 2015-07-30 | 2015-11-04 | 哈尔滨工程大学 | Optical fiber gyroscope with optical fiber ring adopting double-ring design |
| CN105841724A (en) * | 2016-03-24 | 2016-08-10 | 北京理工大学 | Interference type optical fiber sensor for simultaneously measuring pressure and temperature |
| CN105758567A (en) * | 2016-04-21 | 2016-07-13 | 吉林大学 | Fiber interference type pressure sensor based on 3*3 coupler |
| CN106610309A (en) * | 2016-12-27 | 2017-05-03 | 天津市欧斯曼科技有限公司 | A device measuring a liquid level by using the Mach-Zehnder interference technology |
| CN110260947A (en) * | 2019-07-30 | 2019-09-20 | 南昌航空大学 | A kind of fibre optic liquid level sensor and method for sensing |
Non-Patent Citations (1)
| Title |
|---|
| 吴桂峰: "双折射光子晶体光纤压力传感器的研究", 《中国优秀硕士学位论文全文数据库 信息科技辑》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111458668A (en) * | 2020-06-02 | 2020-07-28 | 黑龙江大学 | Vector magnetic field sensor and method for detecting magnetic field by using same |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103557985B (en) | A kind of differential pressure method for sensing and sensor thereof | |
| CN206627147U (en) | A kind of structure of temperature/pressure sensor and the measuring system of temperature and pressure | |
| Zhang et al. | Integrated fiber-optic Fabry-Perot interferometer sensor for simultaneous measurement of liquid refractive index and temperature | |
| CN101196426A (en) | Optical fiber optical grating pressure sensor | |
| CN204228235U (en) | Based on the optical fiber continous way liquid level sensor system of CMFTIR effect | |
| CN103557984B (en) | A kind of method for packing of differential pressure pick-up probe and structure | |
| CN104697609A (en) | Optical fiber interference water level sensor | |
| CN101799334A (en) | Silicon-based optical wave guide temperature sensor based on Mach-Zehnder structure | |
| CN105758567A (en) | Fiber interference type pressure sensor based on 3*3 coupler | |
| CN203551182U (en) | Packaging structure of differential pressure probe | |
| CN112903154A (en) | Extrinsic optical fiber Fabry-Perot interference pressure sensor | |
| CN105223382A (en) | The low fineness F-P optical fiber acceleration transducer of a kind of diaphragm type based on FBG | |
| CN204461547U (en) | Fiber optic interferometric level sensor | |
| CN212721825U (en) | Optical fiber temperature sensor based on temperature sensitive material modulation FP cavity | |
| CN113091970B (en) | Self-healing intelligent all-optical flexible diaphragm | |
| CN110864762A (en) | Input type optical fiber liquid level instrument without installation | |
| CN101710065A (en) | Thin core optical fiber mode interferometer sensor | |
| CN203551183U (en) | Reflective optical-fiber-bundle differential pressure sensor with intensity compensation | |
| CN210923475U (en) | Serum albumin detection system based on optical fiber SPR sensor | |
| CN114137446B (en) | Temperature-sensitive magnetic field eliminating sensing device of FBG cascade optical fiber composite structure | |
| CN206876574U (en) | A kind of optical fiber Streptavidin detecting system based on Fabry Perot interference | |
| CN103134776A (en) | Liquid refractive index absolute measurement sensor based on D-type polarization maintaining optical fibre | |
| CN211402137U (en) | Humidity sensor based on polymer optical fiber mode interferometer | |
| CN103697920A (en) | Optical fiber sensing head and optical fiber sensing system and method for measuring liquid refractivity based on sensing head | |
| CN107063393A (en) | A kind of level sensor system based on single mode multimode single-mode fiber structure and Bragg grating |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20200306 |
|
| RJ01 | Rejection of invention patent application after publication |