CN116858304A - All-fiber multi-parameter detection system and multi-parameter detection method - Google Patents
All-fiber multi-parameter detection system and multi-parameter detection method Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
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Abstract
The system comprises a light source system, a sensing system, a light splitting system and a detection system which are sequentially connected, wherein the light splitting system comprises an optical fiber collimator and a dichroic spectroscope, and the light splitting system is respectively connected with detectors such as a Raman spectrometer, an optical fiber spectrometer and the like through single-mode fibers; the sensing system comprises a first single-mode fiber, a hollow fiber gas chamber, a second single-mode fiber, a hollow fiber resonant cavity, a third single-mode fiber, a fiber grating and a fourth single-mode fiber which are sequentially connected, and the system provided by the application can realize simultaneous detection of multiple parameters such as temperature, gas composition, gas concentration, stress/strain and the like; the temperature detection result is not affected by stress/strain, and the stress/strain detection result can be corrected according to the temperature detection result, so that the problem of temperature-stress/strain cross sensitivity in the existing fiber bragg grating sensing technology is solved; the gas types can be detected in a plurality of ways, and the gas detection limit is low.
Description
Technical Field
The application belongs to the field of optical fiber sensing, and particularly relates to an all-fiber multi-parameter detection system.
Background
The optical fiber has the characteristics of small volume, light weight, large flexibility, good compatibility, strong electrical insulation, corrosion resistance, strong electromagnetic interference resistance and the like, and the optical fiber sensor formed by combining the optical measurement technology has a series of unique advantages in the aspects of multi-parameter detection such as sound field, electric field, temperature, gas, angular velocity, acceleration, stress/strain and the like, such as good reliability, high sensitivity, non-invasiveness, strong adaptability, realization of remote and distributed detection, easiness in networking and the like. Currently, optical fiber sensing has become an important direction for the compact and intelligent development of sensors.
However, the existing optical fiber sensing technology needs to be provided with different sensing optical fibers and signal reading equipment aiming at different detection parameters, and the detection system has a complex structure and cannot realize single-optical-fiber multi-parameter detection; the existing method for simultaneously detecting temperature, stress and strain by utilizing the fiber bragg grating has the problem of cross interference of the temperature and the stress/strain; the existing method for carrying out distributed temperature detection by utilizing a plurality of weak fiber gratings in series has the problems of stress/strain interference, low temperature detection sensitivity, limited distributed temperature monitoring points (with typical values of 20), complex demodulation system, high cost and the like.
Disclosure of Invention
In order to solve the defects existing in the prior art, the application provides an all-fiber multi-parameter detection system which utilizes a single fiber to realize multi-parameter simultaneous detection of temperature, gas components, gas concentration, stress/strain and the like, and solves the problems of temperature-stress/strain cross interference, low temperature detection sensitivity, limited distributed temperature monitoring points, complex demodulation system, higher cost and the like existing in the existing fiber grating sensing technology.
The application adopts the following technical scheme.
An all-fiber multi-parameter detection system is suitable for simultaneously detecting temperature parameters, gas components, gas concentration parameters and stress/strain parameters,
the system comprises a light source system, a sensing system, a light splitting system and a detection system which are sequentially connected, wherein the light splitting system comprises an optical fiber collimator and a dichroic spectroscope, and the sensing system comprises a first single-mode optical fiber, a hollow fiber air chamber, a second single-mode optical fiber, a hollow fiber resonant cavity, a third single-mode optical fiber, a fiber grating and a fourth single-mode optical fiber which are sequentially connected.
The light source system comprises a fiber laser, a broadband light source and a fiber coupler, wherein the fiber coupler is used for coupling an optical signal output by the fiber laser and an optical signal output by the broadband light source into excitation light.
Center wavelength lambda of optical signal output by fiber laser L 400-790nm;
the center wavelength lambam of the optical signal output by the broadband light source is lambada L -10<λm<λ L +10。
The hollow fiber air chamber consists of a single mode fiber, a graded index fiber, a coreless silica fiber, a hollow fiber, a coreless silica fiber, a graded index fiber and a single mode fiber which are welded in sequence; wherein, the transmission loss of the single-mode optical fiber, the graded-index optical fiber, the coreless silicon optical fiber and the hollow optical fiber in the light source and signal light wave bands is less than or equal to 100dB/km.
The hollow fiber air chambers are connected in series through the optical fiber connector or the fusion mode, and the hollow fiber air chambers connected in series are respectively filled with different kinds of high-purity gases with the concentration of more than or equal to 99 percent and with the Raman activity.
The hollow fiber resonant cavity consists of a single mode fiber, a graded index fiber, a coreless silica fiber, a hollow fiber, a coreless silica fiber, a graded index fiber and a single mode fiber which are connected in sequence; the transmission loss of a single mode fiber, a graded index fiber, a coreless silica fiber and an air core fiber in a light source and signal light wave bands is less than or equal to 100dB/km; the diameter of the fiber core of the hollow fiber is more than or equal to 10 mu m; the single-mode optical fiber, the graded-index optical fiber and the coreless silicon optical fiber are connected in a fusion mode; the coreless silicon optical fiber and the hollow optical fiber are mechanically connected through an optical fiber sleeve, and the distance between the end face of the coreless silicon optical fiber and the end face of the hollow optical fiber is 1-5 mu m; the end face of the coreless silicon optical fiber, which is mechanically connected with the hollow optical fiber, is plated with a high-reflection film.
The fiber grating consists of a single mode fiber, a fiber grating and a single mode fiber which are welded in sequence; wherein, the transmission loss of the single-mode fiber and the fiber grating in the light source and the signal light wave band is less than or equal to 50dB/km.
The sensing system is connected with the light splitting system through a fifth single mode fiber, wherein the transmission loss of the fifth single mode fiber in a signal light band is less than or equal to 50dB/km; the first port of the fifth single-mode fiber is connected with the second port of the fourth single-mode fiber through an optical fiber connector, and the second port of the fifth single-mode fiber is fixed on the optical splitting system.
The optical fiber collimator of the light splitting system comprises a first optical fiber collimator, a second optical fiber collimator and a third optical fiber collimator; the first optical fiber collimator is coaxially arranged with the fifth single-mode optical fiber and is used for collimating signal light output by a second port of the fifth single-mode optical fiber;
the second optical fiber collimator is coaxially arranged with the sixth single mode fiber and is used for focusing the gas Raman scattered light so as to couple the gas Raman scattered light into the sixth single mode fiber; the third fiber collimator is coaxially arranged with the eighth single mode fiber and is used for focusing the fiber grating signal so as to couple the fiber grating signal into the eighth single mode fiber.
The transmission loss of the sixth single-mode fiber in the gas Raman scattering optical wave band is less than or equal to 50dB/km; the first port of the device is fixed on the beam-splitting system, the second port is connected with the first port of the seventh single-mode fiber through an optical fiber connector;
the first port of the seventh single-mode fiber is connected with the second port of the sixth single-mode fiber through an optical fiber connector, and the second port of the seventh single-mode fiber is fixed on the Raman spectrometer.
The detection system comprises a Raman spectrometer, a charge coupling element and an optical fiber spectrometer;
the output end of the Raman spectrometer is connected with the charge coupling element;
the input end of the optical fiber spectrometer is fixed with a ninth single-mode optical fiber, the ninth single-mode optical fiber is connected with an eighth single-mode optical fiber through an optical fiber connector, and the first port of the eighth single-mode optical fiber is fixed on the light splitting system.
In a second aspect of the application, an all-fiber multi-parameter detection method is provided,
the method comprises the following steps: step 1, fixedly connecting an all-fiber multi-parameter detection system, and controlling an optical fiber laser and a broadband light source to respectively emit optical signals;
step 2, coupling the optical signals, sequentially inputting the optical signals into a sensing system, and outputting gas Raman scattered light and fiber bragg grating signals;
and step 3, carrying out signal analysis by a Raman spectrometer and an optical fiber spectrometer after carrying out collimation and light splitting on the Raman scattered light and the optical fiber grating signal of the output gas.
Compared with the prior art, the all-fiber multi-parameter detection system provided by the application has the advantages that the temperature detection sensitivity is high (can reach 0.01 ℃), the temperature detection result is not affected by stress/strain, the stress/strain detection result can be corrected according to the temperature detection result, and the temperature-stress/strain cross-sensitivity problem of the existing fiber grating sensing technology is solved; the distributed temperature monitoring points can be set according to actual requirements, and a plurality of hollow optical fibers filled with different types of gases (with Raman activity) are connected in series, so that the number of the maximum monitoring points is equal to the number of the types of gases with Raman activity, and a complex demodulation system is not needed; the gas species can be detected in a plurality, and the gas detection limit is low and can reach ppb level.
Drawings
FIG. 1 is a schematic diagram of an all-fiber multi-parameter detection system in the present application;
FIG. 2 is a schematic diagram of distributed temperature detection of an all-fiber multi-parameter detection system according to the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. The described embodiments of the application are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art without making any inventive effort, are within the scope of the present application.
The application provides an all-fiber multi-parameter detection system, which comprises a light source system, a sensing system, a light splitting system and a detection system which are sequentially connected, wherein the sensing system comprises a first single-mode fiber 4, a hollow fiber air chamber 5, a second single-mode fiber 6, a hollow fiber resonant cavity 7, a third single-mode fiber 8, a fiber grating 9 and a fourth single-mode fiber 10 which are sequentially connected; the light source system comprises a fiber laser 1, a broadband light source 2 and a fiber coupler 3, wherein the fiber coupler 3 is used for coupling an optical signal output by the fiber laser 1 and an optical signal output by the broadband light source 2 into excitation light; the sensing system is connected with the light splitting system through a fifth single-mode optical fiber 11; the fiber collimator of the spectroscopic system 23 includes a first fiber collimator 12, a second fiber collimator 14, and a third fiber collimator 19; the first optical fiber collimator 12 is coaxially arranged with the fifth single-mode optical fiber 11 and is used for collimating the signal light output by the second port of the fifth single-mode optical fiber 11;
the second optical fiber collimator 14 is coaxially arranged with the sixth single-mode optical fiber 15 and is used for focusing the gas Raman scattered light to couple into the sixth single-mode optical fiber 15; the third fiber collimator 19 is coaxially disposed with the eighth single mode fiber 20, and is used for focusing the fiber bragg grating signal, so that the fiber bragg grating signal is coupled into the eighth single mode fiber 20; the detection system comprises a Raman spectrometer 17, a charge coupled device 18 and an optical fiber spectrometer 22;
the embodiment specifically includes: the optical fiber laser comprises an optical fiber laser 1, a broadband light source 2, an optical fiber coupler 3, a first single-mode optical fiber 4, an air core optical fiber air chamber 5, a second single-mode optical fiber 6, an air core optical fiber resonant cavity 7, a third single-mode optical fiber 8, an optical fiber grating 9, a fourth single-mode optical fiber 10, a fifth single-mode optical fiber 11, an optical fiber collimator 12, a dichroic spectroscope 13, an optical fiber collimator 14, a sixth single-mode optical fiber 15, a seventh single-mode optical fiber 16, a Raman spectrometer 17, a charge coupling element 18, an optical fiber collimator 19, an eighth single-mode optical fiber 20, a ninth single-mode optical fiber 21, an optical fiber spectrometer 22 and a light splitting system 23.
The optical fiber laser 1 is a single longitudinal mode, narrow linewidth, continuous wave and optical fiber coupling output laser, is a laser source for detecting temperature, gas components and concentration, and outputs a central wavelength lambda L Is a value in the range of 400-790 nm.
The broadband light source 2 according to the application, a light source for stress/strain detection, outputs a wavelength coverage (lambda L -10)～(λ L +10)nm。
The optical fiber coupler 3 of the present application is used for coupling the light output by the optical fiber laser 1 and the broadband light source 2 into excitation light. When in use, the input port a is connected with the output port of the fiber laser 1 through the fiber connector, the input port b is connected with the output port of the broadband light source 2 through the fiber connector, and the output port c is connected with the first port of the first single-mode fiber 4 through the fiber connector.
The first single mode fiber 4 of the present application is used for inputting excitation light into the sensing system. The transmission loss of the light source in the wave band of the light source is less than or equal to 50dB/km; the first port of the first single-mode optical fiber 4 is connected with the output port c of the optical fiber coupler 3 through an optical fiber connector, and the second port of the first single-mode optical fiber 4 is connected with the first port of the hollow fiber air chamber 5 through an optical fiber connector or in a fusion welding mode.
The hollow fiber air chamber 5 is a temperature sensing element and is used as an internal standard air chamber at the same time, so that the accuracy of gas concentration detection is improved. The optical fiber splice consists of a single mode fiber, a graded index fiber, a coreless silica fiber, an air core fiber, a coreless silica fiber, a graded index fiber and a single mode fiber in a fusion mode. The transmission loss of a single-mode fiber, a graded index fiber, a coreless silica fiber and an air core fiber in a light source and a signal light wave band is less than or equal to 100dB/km, and it is understood that the light source comprises an optical signal output by a fiber laser 1 and a broadband light source 2; the signal light mainly refers to gas Raman scattered light excited by an optical signal output by the fiber laser 1, the wave band of the signal light is related to the wavelength of the excited light and the type of the gas, and the specific formula is as follows: w=1/λ L -1/λ Gas
Wherein W is the frequency shift of the Raman peak of the gas, lambda L Lambda is the central wavelength of the excitation light Gas Is the wavelength of the gas Raman scattered light; the diameter of the fiber core of the hollow fiber is more than or equal to 10 mu m; graded index optical fibers, coreless silica optical fibers are used for mode field coupling between single mode fibers and hollow core optical fibers. When in use, the hollow fiber air chamber 5 is filled with high-purity gas (different from the gas to be measured) with certain pressure and Raman activity, and it is understood that the gas with Raman activity in the application refers to the gas which can generate spontaneous Raman scattering phenomenon under the irradiation of laser. Typically, all gas molecules in nature have raman activity, except for monoatomic gas molecules such as helium, neon, argon, krypton, xenon, radon, and the like. The range of the pressure of the filling gas in the hollow fiber gas chamber 5 is unlimited, and the value is specifically determined according to the Raman activity of the gas, the output power of the fiber laser 1, the length of the hollow fiber gas chamber 5 and the like. If the gas Raman activity is large, the output power of the fiber laser 1 is large, and the length of the hollow fiber air chamber 5 is long, the filled gas pressure can be smaller; the filling gas is not the same as the gas to be measured, such as H2, CO2, SO2, CH4, C2H6, C2H4, C2H2 and the like, and can be used as the filling gas, and it is understood that the high-purity gas in the application refers to the gas with the concentration of more than or equal to 99%. The first port of the single-mode optical fiber connector is connected with the second port of the single-mode optical fiber 4 through an optical fiber connector or in a fusion mode, and the second port of the single-mode optical fiber 6 is connected with the first port of the single-mode optical fiber through the optical fiber connector or in a fusion mode. In particular, in order to realize distributed temperature detection, as shown in fig. 2, a plurality of hollow fiber air chambers 5 may be connected in series by a fiber connector or in a fusion manner, and the plurality of hollow fibers connected in series are respectively filled with different kinds of high-purity gases with certain pressure and raman activity. During analysis, temperature information is read through the recorded position of an internal standard gas characteristic Raman peak in the gas Raman spectrum, namely Raman frequency shift change.
The second single-mode optical fiber 6 is used for connecting the hollow fiber air chamber 5 and the hollow fiber resonant cavity 7. The transmission loss of the light source and the signal light wave band is less than or equal to 50dB/km; the first port is connected with the second port of the hollow fiber air chamber 5 through a fiber connector or in a fusion manner, and the second port is connected with the first port of the hollow fiber resonant cavity 7 through a fiber connector or in a fusion manner.
The hollow fiber resonant cavity 7 is a gas sensing element and consists of a single mode fiber, a graded index fiber, a coreless silica fiber, a hollow fiber, a coreless silica fiber, a graded index fiber and a single mode fiber. The transmission loss of a single mode fiber, a graded index fiber, a coreless silica fiber and an air core fiber in a light source and signal light wave bands is less than or equal to 100dB/km; the diameter of the fiber core of the hollow fiber is more than or equal to 10 mu m; the graded index optical fiber and the coreless silicon optical fiber are used for mode field coupling between the single mode fiber and the hollow fiber; the single-mode optical fiber, the graded-index optical fiber and the coreless silicon optical fiber are all connected in a fusion mode; the coreless silicon optical fiber and the hollow optical fiber are mechanically connected through an optical fiber sleeve, the distance between the end face of the coreless silicon optical fiber and the end face of the hollow optical fiber is controlled to be 1-5 mu m, and a channel is provided for gas exchange between the hollow optical fiber resonant cavity and the external environment; the end surface of the coreless silicon optical fiber mechanically connected with the hollow optical fiber is plated with a high-reflection film which outputs the central wavelength lambda in the optical fiber laser 1 L The reflectivity of the light source is more than or equal to 0.90, and the transmittance of the light source for gas Raman scattering is more than or equal to 0.90; the first port of the hollow fiber resonant cavity 7 is connected with the second port of the second single-mode fiber 6 through an optical fiber connector or in a fusion mode, and the second port is connected with the first port of the third single-mode fiber 8 through an optical fiber connector or in a fusion mode. During analysis, the gas composition is judged by the recorded positions (Raman frequency shifts) of the characteristic Raman peaks of each gas in the gas Raman spectrum, and the gas concentration is calculated by the ratio of the intensity (peak height/peak area) of each characteristic Raman peak of each gas to the intensity (peak height/peak area) of the characteristic Raman peak of the internal standard gas.
The third single mode fiber 8 is used for connecting the hollow fiber resonant cavity 7 with the fiber grating 9. The transmission loss of the light source and the signal light wave band is less than or equal to 50dB/km; the first port is connected with the second port of the hollow fiber resonant cavity 7 through a fiber connector or in a fusion manner, and the second port is connected with the first port of the fiber grating 9 through a fiber connector or in a fusion manner.
The optical fiber of the applicationThe grating 9 is a stress/strain sensor and is used as a high-pass filter for filtering the laser light output by the fiber laser 1 and the laser wavelength lambda L The same gas Rayleigh scatters light. The optical fiber is formed by welding a single mode fiber, a fiber grating and a single mode fiber. Wherein, the transmission loss of the single-mode fiber and the fiber bragg grating in the light source and the signal light wave band is less than or equal to 50dB/km; the first port of the optical fiber is connected with the second port of the third single-mode optical fiber 8 through an optical fiber connector or in a fusion mode, and the second port of the optical fiber is connected with the first port of the fourth single-mode optical fiber 10 through an optical fiber connector or in a fusion mode. During analysis, stress/strain information is read through the recorded change of the central wavelength of the fiber bragg grating signal, and compensation is performed through the read temperature information.
Specifically, the change of the center wavelength of the fiber bragg grating signal is simultaneously affected by stress/strain and temperature, and the formula is as follows:
Δλ＝λ(1－Pe)Δε+λ(α－ξ)ΔT
wherein delta lambda is the variation of the central wavelength of the fiber bragg grating signal, lambda is the central wavelength of the fiber bragg grating signal, and Pe is the effective elasto-optical coefficient; delta epsilon is the stress/strain variation, alpha is the expansion coefficient of the elastomer, zeta is the thermo-optic coefficient of the optical fiber, and delta T is the temperature variation.
Δλ can be directly obtained through measurement results, pe, α, and ζ are constants, and λ is the selected central wavelength of the fiber bragg grating. Therefore, after knowing the temperature change amount Δt, the stress/strain change amount Δε can be calculated directly based on the above formula.
The fourth single mode fiber 10 of the present application is used for outputting signal light to a sensing system. The transmission loss of the optical fiber in a signal optical wave band is less than or equal to 50dB/km; the first port is connected to the second port of the fiber bragg grating 9 by a fiber optic connector or by fusion, and the second port is connected to the first port of the single-mode fiber 11 by a fiber optic connector.
The fifth single mode fiber 11 according to the present application is used for inputting signal light into a spectroscopic system. The transmission loss of the optical fiber in a signal optical wave band is less than or equal to 50dB/km; the first port is connected to a second port of the single-mode optical fiber 10 by an optical fiber connector, and the second port is fixed to the optical splitting system 16.
The optical fiber collimator 12 is used for collimating the signal light output by the second port of the fifth single-mode optical fiber 11.
The dichroic spectroscope 13 is used for separating the fiber grating signal from the gas Raman scattered light. The reflectivity of the fiber grating signal is more than or equal to 0.98, and the transmittance of the fiber grating signal to the gas Raman scattered light is more than or equal to 0.93.
The fiber collimator 14 of the present application is used for focusing the gas raman scattered light so as to couple the gas raman scattered light into the sixth single mode fiber 15.
The sixth single-mode fiber 15 of the present application is used for outputting gas raman scattered light to a spectroscopic system. The transmission loss of the gas Raman scattering optical wave band is less than or equal to 50dB/km; the first port is fixed to the spectroscopic system 23 and the second port is connected to the first port of the single mode fiber 16 by a fiber optic connector.
The seventh single mode fiber 16 of the present application is used to couple the gas raman scattered light into the slit of the raman spectrometer 17. The transmission loss of the gas Raman scattering optical wave band is less than or equal to 50dB/km; the first port is connected to a second port of the single mode fiber 15 via a fiber optic connector, and the second port is fixed to the raman spectrometer 17.
The raman spectrometer 17 of the present application is used for diffracting and splitting gas raman scattered light with different wavelengths.
The charge coupled device 18 of the present application is used for detecting and recording gas raman scattered light of different wavelengths.
The fiber collimator 19 of the present application is used for focusing the fiber grating signal so as to couple the fiber grating signal into the single mode fiber 20.
The eighth single-mode fiber 20 of the present application is used for outputting the fiber grating signal to the spectroscopic system. The transmission loss of the fiber grating is less than or equal to 50dB/km in the fiber grating signal wave band; the first port is fixed to the spectroscopic system 23, and the second port is connected to the first port of the single-mode optical fiber 21 by an optical fiber connector.
The ninth single mode fiber 21 of the present application is used for coupling the fiber bragg grating signal into the fiber spectrometer 22. The transmission loss of the fiber grating is less than or equal to 50dB/km in the fiber grating signal wave band; the first port is connected to a second port of the single mode fiber 20 via a fiber optic connector, and the second port is secured to the fiber optic spectrometer 22.
The fiber spectrometer 22 is used for detecting and recording fiber grating signals.
The beam splitting system 23 of the present application is used for fixing the single-mode optical fiber 11, the optical fiber collimator 12, the dichroic beam splitter 13, the optical fiber collimator 14, the single-mode optical fiber 15, the optical fiber collimator 19 and the single-mode optical fiber 20.
To better illustrate the effects achieved by the present application, an all-fiber multi-parameter (temperature, gas composition and concentration, stress/strain) detection system is presented further below in conjunction with the examples.
In the specific embodiment, the central wavelength of the output of the fiber laser is 532nm, and the maximum output power is 100mW; the output wavelength of the broadband light source covers 500-550 nm; the hollow fiber air chamber is the same as the hollow fiber used by the hollow fiber resonant cavity, the fiber core is 20 mu m, and the transmission loss is less than or equal to 100dB/km at 400-1200 nm; the length of the hollow fiber used by the hollow fiber air chamber is 10cm; SF (sulfur hexafluoride) for filling 1bar in hollow fiber air chamber 6 The gas concentration is 0.99999; the length of the hollow fiber used by the hollow fiber resonant cavity is 2m; the reflectivity of the high-reflectivity film plated on the hollow fiber resonant cavity at 532nm is more than or equal to 0.99, and the transmissivity at the wave band of 550-700 nm is more than or equal to 0.90; h of 5bar is filled in hollow fiber resonant cavity 2 、CO、CO 2 、CH 4 、C 2 H 6 、C 2 H 4 C 2 H 2 Each gas concentration was 500ppm; the center wavelength of the fiber grating is 532nm. It will be appreciated that in this embodiment, the gas filled is a simulated gas for dissolving fault characteristics in transformer oil, and in other embodiments, other gases may be simulated according to actual detection requirements.
The embodiment also provides an all-fiber multi-parameter detection method, which comprises the following steps: step 1, fixedly connecting an all-fiber multi-parameter detection system, and controlling an optical fiber laser and a broadband light source to respectively emit optical signals;
step 2, coupling the optical signals, sequentially inputting the optical signals into a sensing system, and outputting gas Raman scattered light and fiber bragg grating signals;
and step 3, carrying out signal analysis by a Raman spectrometer and an optical fiber spectrometer after carrying out collimation and light splitting on the Raman scattered light and the optical fiber grating signal of the output gas.
Specifically, light emitted by the fiber laser and the broadband light source is coupled into the fiber coupler through the port a and the port b of the fiber coupler respectively, is coupled into a beam of light in the fiber coupler, and is output through the port c of the fiber coupler; the output laser and the light of the broadband light source are guided by a first single mode fiber and enter the hollow fiber air chamber, and the laser simultaneously excites the gas Raman scattered light 1 in the hollow fiber air chamber; the light of the laser and broadband light source and the gas Raman scattered light 1 are guided by the second single mode fiber and enter the hollow fiber resonant cavity, and the laser simultaneously excites the gas Raman scattered light 2 in the hollow fiber resonant cavity; the light of the laser and the broadband light source, the gas Raman scattered light 1 and the gas Raman scattered light 2 are guided by a third single mode fiber and enter the fiber grating, the laser is filtered by the fiber grating, and the light of the broadband light source simultaneously excites the fiber grating signal; the light of the broadband light source, the gas Raman scattered light 1, the gas Raman scattered light 2 and the fiber grating signal are guided by a fourth single mode fiber and a fifth single mode fiber in sequence and are collimated by a first fiber collimator; the collimated gas Raman scattered light 1 and 2 and the fiber bragg grating signal are separated by a dichroic mirror; the gas Raman scattered light 1 and 2 penetrate through a dichroic spectroscope, enter a sixth single mode fiber after being focused by a second optical fiber collimator, enter a Raman spectrometer after being guided by the sixth single mode fiber and the seventh single mode fiber in sequence, and are detected and recorded by a charge coupling element after being split by the Raman spectrometer; the fiber grating signal is reflected by the dichroic spectroscope, enters the eighth single mode fiber after being focused by the third fiber collimator, enters the fiber spectrometer after being guided by the eighth single mode fiber and the ninth single mode fiber in sequence, and is detected and recorded by the fiber spectrometer.
Compared with the prior art, the all-fiber multi-parameter detection system provided by the application has the advantages that the temperature detection sensitivity is high (can reach 0.01 ℃), the temperature detection result is not affected by stress/strain, the stress/strain detection result can be corrected according to the temperature detection result, and the temperature-stress/strain cross-sensitivity problem of the existing fiber grating sensing technology is solved; the distributed temperature monitoring points can be set according to actual requirements, and a plurality of hollow optical fibers filled with different types of gases (with Raman activity) are connected in series, so that the number of the maximum monitoring points is equal to the number of the types of gases with Raman activity, and a complex demodulation system is not needed; the gas species can be detected in a plurality, and the gas detection limit is low and can reach ppb level.
The present disclosure may be a system, method, and/or computer program product. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for causing a processor to implement aspects of the present disclosure.
The computer readable storage medium may be a tangible device that can hold and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer-readable storage medium would include the following: portable computer disks, hard disks, random Access Memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static Random Access Memory (SRAM), portable compact disk read-only memory (CD-ROM), digital Versatile Disks (DVD), memory sticks, floppy disks, mechanical coding devices, punch cards or in-groove structures such as punch cards or grooves having instructions stored thereon, and any suitable combination of the foregoing. Computer-readable storage media, as used herein, are not to be construed as transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., optical pulses through fiber optic cables), or electrical signals transmitted through wires.
The computer readable program instructions described herein may be downloaded from a computer readable storage medium to a respective computing/processing device or to an external computer or external storage device over a network, such as the internet, a local area network, a wide area network, and/or a wireless network. The network may include copper transmission cables, fiber optic transmissions, wireless transmissions, routers, firewalls, switches, gateway computers and/or edge servers. The network interface card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium in the respective computing/processing device.
Computer program instructions for performing the operations of the present disclosure can be assembly instructions, instruction Set Architecture (ISA) instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, c++ or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer readable program instructions may be executed entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any kind of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or may be connected to an external computer (for example, through the Internet using an Internet service provider). In some embodiments, aspects of the present disclosure are implemented by personalizing electronic circuitry, such as programmable logic circuitry, field Programmable Gate Arrays (FPGAs), or Programmable Logic Arrays (PLAs), with state information of computer readable program instructions, which can execute the computer readable program instructions.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present application and not for limiting the same, and although the present application has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made to the specific embodiments of the application without departing from the spirit and scope of the application, which is intended to be covered by the claims.
Claims (12)
1. An all-fiber multi-parameter detection system is suitable for simultaneously detecting temperature parameters, gas components, gas concentration parameters and stress/strain parameters, and is characterized in that,
the system comprises a light source system, a sensing system, a light splitting system and a detection system which are sequentially connected, wherein the light splitting system comprises an optical fiber collimator and a dichroic spectroscope (13), and the sensing system comprises a first single-mode optical fiber (4), an hollow fiber air chamber (5), a second single-mode optical fiber (6), a hollow fiber resonant cavity (7), a third single-mode optical fiber (8), a fiber bragg grating (9) and a fourth single-mode optical fiber (10) which are sequentially connected.
2. An all-fiber multi-parameter sensing system according to claim 1, wherein:
the light source system comprises a fiber laser (1), a broadband light source (2) and a fiber coupler (3), wherein the fiber coupler (3) is used for coupling an optical signal output by the fiber laser (1) and an optical signal output by the broadband light source (2) into excitation light.
3. An all-fiber multi-parameter sensing system according to claim 2, wherein:
center wavelength lambda of optical signal output from optical fiber laser (1) L 400-790nm;
the center wavelength lambda m of the optical signal output by the broadband light source (2) is lambda L -10<λm<λ L +10。
4. An all-fiber multi-parameter sensing system according to claim 1, wherein:
the hollow fiber air chamber (5) consists of a single mode fiber, a graded index fiber, a coreless silica fiber, a hollow fiber, a coreless silica fiber, a graded index fiber and a single mode fiber which are welded in sequence; wherein, the transmission loss of the single-mode optical fiber, the graded-index optical fiber, the coreless silicon optical fiber and the hollow optical fiber in the light source and signal light wave bands is less than or equal to 100dB/km.
5. An all-fiber multi-parameter sensing system according to claim 4, wherein:
the hollow fiber air chambers (5) are connected in series through the optical fiber connector or the fusion connection mode, and the hollow fiber air chambers (5) connected in series are respectively filled with different kinds of high-purity gases with the concentration of more than or equal to 99 percent and with the Raman activity.
6. An all-fiber multi-parameter sensing system according to claim 1, wherein:
the hollow fiber resonant cavity (7) consists of a single mode fiber, a graded index fiber, a coreless silica fiber, a hollow fiber, a coreless silica fiber, a graded index fiber and a single mode fiber which are connected in sequence; the transmission loss of a single mode fiber, a graded index fiber, a coreless silica fiber and an air core fiber in a light source and signal light wave bands is less than or equal to 100dB/km; the diameter of the fiber core of the hollow fiber is more than or equal to 10 mu m; the single-mode optical fiber, the graded-index optical fiber and the coreless silicon optical fiber are connected in a fusion mode; the coreless silicon optical fiber and the hollow optical fiber are mechanically connected through an optical fiber sleeve, and the distance between the end face of the coreless silicon optical fiber and the end face of the hollow optical fiber is 1-5 mu m; the end face of the coreless silicon optical fiber, which is mechanically connected with the hollow optical fiber, is plated with a high-reflection film.
7. An all-fiber multi-parameter sensing system according to claim 1, wherein:
the fiber bragg grating (9) consists of a single mode fiber, a fiber bragg grating and a single mode fiber which are welded in sequence; wherein, the transmission loss of the single-mode fiber and the fiber grating in the fiber grating (9) in the light source and the signal light wave band is less than or equal to 50dB/km.
8. An all-fiber multi-parameter sensing system according to claim 1, wherein:
the sensing system is connected with the light splitting system through a fifth single-mode fiber (11), wherein the transmission loss of the fifth single-mode fiber (11) in a signal light wave band is less than or equal to 50dB/km; the first port of the fifth single-mode fiber (11) is connected with the second port of the fourth single-mode fiber (10) through an optical fiber connector, and the second port of the fifth single-mode fiber is fixed on the optical splitting system.
9. An all-fiber multi-parameter sensing system according to claim 8, wherein:
the optical fiber collimator of the light splitting system (23) comprises a first optical fiber collimator (12), a second optical fiber collimator (14) and a third optical fiber collimator (19); the first optical fiber collimator (12) is coaxially arranged with the fifth single-mode optical fiber (11) and is used for collimating signal light output by the second port of the fifth single-mode optical fiber (11);
the second optical fiber collimator (14) is coaxially arranged with the sixth single-mode optical fiber (15) and is used for focusing the gas Raman scattered light so as to couple the gas Raman scattered light into the sixth single-mode optical fiber (15); the third fiber collimator (19) is coaxially arranged with the eighth single-mode fiber (20) and is used for focusing the fiber grating signal so as to couple the fiber grating signal into the eighth single-mode fiber (20).
10. An all-fiber multi-parameter sensing system according to claim 9, wherein:
the transmission loss of the sixth single-mode fiber (15) in the gas Raman scattering optical wave band is less than or equal to 50dB/km; the first port of the optical fiber type optical fiber connector is fixed on the optical splitting system (23), and the second port is connected with the first port of the seventh single-mode optical fiber (16) through the optical fiber connector;
the first port of the seventh single-mode fiber (16) is connected with the second port of the sixth single-mode fiber (15) through an optical fiber connector, and the second port of the seventh single-mode fiber is fixed on a Raman spectrometer (17).
11. An all-fiber multi-parameter sensing system according to claim 10, wherein:
the detection system comprises a Raman spectrometer (17), a charge coupling element (18) and an optical fiber spectrometer (22);
wherein the output end of the Raman spectrometer (17) is connected with a charge coupling element (28);
the input end of the optical fiber spectrometer (22) is fixed with a ninth single-mode optical fiber (21), the ninth single-mode optical fiber (21) is connected with an eighth single-mode optical fiber (20) through an optical fiber connector, and a first port of the eighth single-mode optical fiber (20) is fixed on the optical splitting system.
12. An all-fiber multi-parameter detection method is characterized in that,
the method comprises the following steps: step 1, fixedly connecting an all-fiber multi-parameter detection system, and controlling an optical fiber laser and a broadband light source to respectively emit optical signals;
step 2, coupling the optical signals, sequentially inputting the optical signals into a sensing system, and outputting gas Raman scattered light and fiber bragg grating signals;
and step 3, carrying out signal analysis by a Raman spectrometer and an optical fiber spectrometer after carrying out collimation and light splitting on the Raman scattered light and the optical fiber grating signal of the output gas.
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