CN116735535A - End face probe type quasi-distributed optical fiber hydrogen sensing system - Google Patents
End face probe type quasi-distributed optical fiber hydrogen sensing system Download PDFInfo
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- 239000001257 hydrogen Substances 0.000 title claims abstract description 145
- 229910052739 hydrogen Inorganic materials 0.000 title claims abstract description 145
- 239000013307 optical fiber Substances 0.000 title claims abstract description 41
- 239000000523 sample Substances 0.000 title claims abstract description 17
- 125000004435 hydrogen atom Chemical class [H]* 0.000 title 1
- 230000003287 optical effect Effects 0.000 claims abstract description 197
- 150000002431 hydrogen Chemical class 0.000 claims abstract description 123
- 238000001514 detection method Methods 0.000 claims abstract description 46
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 239000004065 semiconductor Substances 0.000 claims description 19
- 239000000835 fiber Substances 0.000 claims description 11
- 238000009827 uniform distribution Methods 0.000 claims description 9
- 230000004927 fusion Effects 0.000 claims description 7
- 238000003780 insertion Methods 0.000 claims description 6
- 230000037431 insertion Effects 0.000 claims description 6
- 238000002310 reflectometry Methods 0.000 claims description 5
- 230000036632 reaction speed Effects 0.000 abstract description 6
- 230000008859 change Effects 0.000 description 5
- 238000013480 data collection Methods 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 238000012544 monitoring process Methods 0.000 description 4
- 230000002269 spontaneous effect Effects 0.000 description 4
- 230000008569 process Effects 0.000 description 3
- 238000012937 correction Methods 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 230000035559 beat frequency Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/4738—Diffuse reflection, e.g. also for testing fluids, fibrous materials
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/4738—Diffuse reflection, e.g. also for testing fluids, fibrous materials
- G01N21/474—Details of optical heads therefor, e.g. using optical fibres
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F17/00—Digital computing or data processing equipment or methods, specially adapted for specific functions
- G06F17/10—Complex mathematical operations
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N2021/0106—General arrangement of respective parts
- G01N2021/0112—Apparatus in one mechanical, optical or electronic block
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
- G01N21/4738—Diffuse reflection, e.g. also for testing fluids, fibrous materials
- G01N2021/4764—Special kinds of physical applications
Abstract
The application provides an end face probe type quasi-distributed optical fiber hydrogen sensing system, which comprises a demodulation module, a detection module and a sensor module, wherein the demodulation module is used for receiving an optical signal returned by the detection module and converting the optical signal into an electric signal so as to invert the hydrogen concentration detected by each reflection type hydrogen sensor; the sensing detection module comprises a sensing array unit and a power compensation unit, wherein the sensing array unit and the power compensation unit are both connected with the demodulation module, and the sensing array unit is connected with the power compensation unit; the sensing array unit is used for acquiring optical signals of detection points corresponding to the reflection-type hydrogen sensors through the reflection-type hydrogen sensors, the power compensation unit performs power compensation on the reflection-type hydrogen sensors, and the sensing array unit and the power compensation unit are respectively and correspondingly provided with an optical branching device connected with each reflection-type hydrogen sensor by adjusting the light splitting ratio of the optical branching device corresponding to the reflection-type hydrogen sensors. The application is helpful to improve the stability and reaction speed of the sensor.
Description
Technical Field
The application relates to the technical field of hydrogen monitoring, in particular to an end face probe type quasi-distributed optical fiber hydrogen sensing system.
Background
With the development of modern industry, hydrogen is widely used as an important energy source in various industrial departments, but the inflammable and explosive characteristics of hydrogen can pose a great threat to life and property safety, so how to monitor the hydrogen concentration is particularly important.
Chinese patent publication No. CN114002185a discloses a multi-point dispersion spectrum measuring device and method based on optical frequency modulation continuous wave, the frequency modulation laser outputs continuous light whose frequency varies linearly with time, and the second coupler transmits 1% of the continuous light as reference light to the polarization controller for modulating polarization direction; 99% of continuous light is used as detection light to enter the circulator from the 1 port and is simultaneously output to a plurality of sensors from the 2 port; each sensor comprises a correction light path and gas Chi Guanglu which are arranged in parallel, the correction light path and the gas Chi Guanglu are converted into beat frequency electric signals through a first balance detector and then are transmitted to a signal processor for processing and determining the concentration of gas in a gas tank, but the scheme outputs the light signals to a plurality of sensors which are connected in series through a circulator at the same time, so that the condition of insufficient power exists in the sensor far away from the circulator, the stability and the reaction speed of the sensor are reduced, and therefore, the stability and the reaction speed of the sensor are improved by the end face probe type quasi-distributed optical fiber hydrogen sensing system.
Disclosure of Invention
In view of this, the application provides an end face probe type quasi-distributed optical fiber hydrogen sensing system, which distributes the split ratio of the optical splitter corresponding to the sensor in the sensing array unit and the power compensation unit through a power uniform distribution algorithm so as to improve the stability and the reaction speed of the sensor.
The application provides an end face probe type quasi-distributed optical fiber hydrogen sensing system, which comprises a demodulation module and a sensing detection module, wherein the demodulation module is connected with the sensing detection module,
the demodulation module is used for receiving the optical signals returned by the sensing detection module and converting the optical signals into electric signals so as to invert the hydrogen concentration detected by each reflection type hydrogen sensor;
the sensing detection module comprises a sensing array unit and a power compensation unit, wherein the sensing array unit and the power compensation unit are both connected with the demodulation module, and the sensing array unit is connected with the power compensation unit;
the sensing array unit is used for acquiring optical signals corresponding to detection points of the reflection-type hydrogen sensors through the reflection-type hydrogen sensors, the power compensation unit performs power compensation on the reflection-type hydrogen sensors, the sensing detection module adjusts the light splitting ratio of the optical splitters corresponding to the reflection-type hydrogen sensors based on a power uniform distribution algorithm, and the sensing array unit and the power compensation unit are correspondingly provided with the optical splitters connected with the reflection-type hydrogen sensors.
On the basis of the above technical scheme, preferably, the sensing array unit comprises a first reflection-type hydrogen sensor, a second reflection-type hydrogen sensor, a first optical splitter and a second optical splitter, wherein the input end of the first optical splitter is connected with the demodulation module, the first output end of the first optical splitter is connected with the first reflection-type hydrogen sensor, the second output end of the first optical splitter is connected with the input end of the second optical splitter, and the output end of the second optical splitter is connected with the second reflection-type hydrogen sensor.
On the basis of the above technical scheme, preferably, the power compensation unit comprises a compensation light source, a first optical splitter and a second optical splitter, wherein the input end of the first optical splitter is connected with the compensation light source, the first output end of the first optical splitter is connected with the first reflection-type hydrogen sensor, the second output end of the first optical splitter is connected with the input end of the second optical splitter, and the output end of the second optical splitter is connected with the second reflection-type hydrogen sensor.
Still further preferably, the demodulation module includes a sensing light source, a semiconductor optical amplifier, a signal transmitter, an erbium-doped fiber amplifier, a fifth optical splitter, a circulator, a first photodetector, a second photodetector, and a data acquisition unit, wherein,
the sensing light source is connected with the semiconductor optical amplifier, the semiconductor optical amplifier is respectively connected with the signal transmitter and the erbium-doped optical fiber amplifier, the erbium-doped optical fiber amplifier is connected with the fifth optical divider, a first output end of the fifth optical divider is connected with a first port of the circulator, a second output end of the fifth optical divider is connected with the first photoelectric detector, a second port of the circulator is connected with the sensing detection module, a third port of the circulator is connected with the second photoelectric detector, and the data acquisition unit is respectively connected with the signal transmitter, the first photoelectric detector and the second photoelectric detector.
Still further preferably, the power uniform distribution algorithm specifically includes:
wherein ,the power allocated to each of the reflection-type hydrogen sensors is +.>For the light power of the pulse light emitted by the sensing light source after being modulated by the semiconductor optical amplifier, the fluctuation power caused by the light beam emitted by the sensing light source after being amplified by the erbium-doped optical fiber amplifier is delta P +.>Before reaching the nth reflective hydrogen sensorThe insertion loss of the optical branching device of each stage, n is the number of the reflection type hydrogen sensor, < ->For self-loss of the optical fibers in the demodulation module and the sensing detection module, D is the distance between two adjacent reflection type hydrogen sensors, and +.>And the optical fiber fusion loss is generated in the demodulation module and the sensing detection module.
Still further preferably, the optical power expression received by the first photodetector is:
wherein ,for the optical power received by the first photodetector, r is the reflectivity of the reflective hydrogen sensor, +.>For the split ratio of each level of optical splitters in the sensing detection module, and (2)>The optical fiber is self-loss and fusion loss in the sensing detection module.
Still further preferably, the optical power expression received by the second photodetector is:
wherein ,for the optical power received by the second photodetector, < >>For the insertion loss of said fifth optical splitter,>the optical fiber loss and the welding loss in the demodulation module.
Still further preferably, the fifth optical splitter has a splitting ratio of 99:1, wherein the first output end of the fifth optical splitter outputs 99% of optical signals, and the second output end of the fifth optical splitter outputs 1% of optical signals.
Still further preferably, the first optical splitter and the third optical splitter are each 1×2 couplers.
Still further preferably, the first optical splitter and the third optical splitter have a first optical splitting ratio, and the second optical splitter and the fourth optical splitter have a second optical splitting ratio.
Compared with the prior art, the end face probe type quasi-distributed optical fiber hydrogen sensing system has the following beneficial effects:
(1) The split ratio of the optical splitter is arranged in the sensing array unit and the power compensation unit corresponding to the reflective hydrogen sensor through a power uniform distribution algorithm, and the power compensation unit performs power compensation on the reflective hydrogen sensor by introducing continuous optical power compensation so as to improve the stability and the reaction speed of the reflective hydrogen sensor;
(2) The sensing array unit can replace the reflection-type hydrogen sensor independently, so that the sensor replacement is more convenient, meanwhile, the reflection-type hydrogen sensors are not interfered, and the reflection-type hydrogen sensors are flexibly distributed to meet various hydrogen monitoring scenes.
Drawings
In order to more clearly illustrate the embodiments of the application or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a light hydrogen sensor system according to the present application;
FIG. 2 is a schematic diagram of a hydrogen sensor system according to the present application;
FIG. 3 is a schematic diagram of a hydrogen sensor system with a multi-stage optical splitter according to the present application;
FIG. 4 is a schematic flow chart of the optical power ratio signal data processing process according to the present application;
FIG. 5 is a power distribution diagram of a reflection type hydrogen sensor with a bus topology according to the present application.
Reference numerals illustrate: 1. a demodulation module; 11. a sensing light source; 12. a semiconductor optical amplifier; 13. a signal transmitter; 14. an erbium-doped fiber amplifier; 15. a fifth optical splitter; 16. a circulator; 17. a first photodetector; 18. a second photodetector; 19. a data acquisition unit; 2. a sensing detection module; 21. a sensor array unit; 211. a first reflective hydrogen sensor; 212. a second reflective hydrogen sensor; 213. a first optical splitter; 214. a second optical splitter; 22. a power compensation unit; 221. a compensating light source; 222. a third optical splitter; 223. and a fourth optical splitter.
Detailed Description
The following description of the embodiments of the present application will clearly and fully describe the technical aspects of the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present application without making any inventive effort, are intended to fall within the scope of the present application.
The application discloses an end face probe type quasi-distributed optical fiber hydrogen sensing system, referring to fig. 1, the optical fiber hydrogen sensing system comprises a demodulation module 1 and a sensing detection module 2, the demodulation module 1 is connected with the sensing detection module 2, wherein,
the demodulation module 1 is used for receiving the optical signals returned by the sensing detection module 2 and converting the optical signals into electric signals so as to invert the hydrogen concentration detected by each reflection type hydrogen sensor.
As shown in fig. 2, the demodulation module 1 includes a sensing light source 11, a semiconductor optical amplifier 12, a signal transmitter 13, an erbium-doped fiber amplifier 14, a fifth optical splitter 15, a circulator 16, a first photodetector 17, a second photodetector 18, and a data collection unit 19, wherein,
the sensing light source 11 is connected with the semiconductor optical amplifier 12, the semiconductor optical amplifier 12 is respectively connected with the signal transmitter 13 and the erbium-doped optical fiber amplifier 14, the erbium-doped optical fiber amplifier 14 is connected with the fifth optical splitter 15, the first output end of the fifth optical splitter 15 is connected with the first port of the circulator 16, the second output end of the fifth optical splitter 15 is connected with the first photoelectric detector 17, the second port of the circulator 16 is connected with the sensing detection module 2, the third port of the circulator 16 is connected with the second photoelectric detector 18, and the data acquisition unit 19 is respectively connected with the signal transmitter 13, the first photoelectric detector 17 and the second photoelectric detector 18.
The fifth optical splitter 15 has a splitting ratio of 99:1, the first output end of the fifth optical splitter 15 outputs 99% of optical signals, the second output end of the fifth optical splitter 15 outputs 1% of optical signals, the sensing light source 11 can be an amplified spontaneous emission light source, and the main body part of the amplified spontaneous emission light source is a gain medium erbium-doped fiber and a high-performance pump laser. The amplified spontaneous emission light source generates a broad-spectrum continuous optical signal, which is modulated into a pulse light having a pulse width of 4ns by the semiconductor optical amplifier 12.
In this embodiment, the sensing light source 11, the semiconductor optical amplifier 12, the signal emitter 13, the erbium-doped fiber amplifier 14, the fifth optical splitter 15, the first photodetector 17 and the data acquisition unit 19 form a reference light path, the light emitted by the sensing light source 11 is modulated into pulse light by the semiconductor optical amplifier 12, the pulse light is amplified by the erbium-doped fiber amplifier 14 and then is input into the fifth optical splitter 15 to split 1% of pulse light, and the pulse light is acquired as reference light by the first photodetector 17 to compensate the influence caused by the fluctuation of the light power.
The sensing light source 11, the semiconductor optical amplifier 12, the signal transmitter 13, the erbium-doped optical fiber amplifier 14, the fifth optical splitter 15, the circulator 16, the sensing detection module 2, the second photoelectric detector 18 and the data acquisition unit 19 form a detection light path, light emitted by the sensing light source 11 is modulated into pulse light through the semiconductor optical amplifier 12, the pulse light is amplified by the erbium-doped optical fiber amplifier 14 and then is input into the fifth optical splitter 15 to split 99% of pulse light, the pulse light enters the bus topology sensing array formed by the reflection type hydrogen sensors through the second port of the circulator 16, and reflected light pulses generated by the reflection type hydrogen sensors are received by the second photoelectric detector 18 through the third port of the circulator 16.
The signal generator sends out two paths of electric pulse signals and is responsible for synchronous triggering of the semiconductor optical amplifier 12 and the data acquisition card. The first photoelectric detector 17 and the second photoelectric detector 18 convert the corresponding optical signals into electrical signals and the electrical signals are collected by the data collection unit 19, the signals collected by the data collection unit 19 are transmitted to the PC end of the upper computer through the PCIe interface, and the data collection unit 19 can be a data collection card.
In this embodiment, the sensing detection module 2 includes a sensing array unit 21 and a power compensation unit 22, where the sensing array unit 21 and the power compensation unit 22 are both connected to the demodulation module 1, and the sensing array unit 21 is connected to the power compensation unit 22.
The sensor array unit 21 is configured to obtain optical signals corresponding to the detection points through a plurality of reflection-type hydrogen sensors, where the sensor array unit 21 includes a first reflection-type hydrogen sensor 211, a second reflection-type hydrogen sensor 212, a first optical splitter 213, and a second optical splitter 214, an input end of the first optical splitter 213 is connected to the demodulation module 1, a first output end of the first optical splitter 213 is connected to the first reflection-type hydrogen sensor 211, a second output end of the first optical splitter 213 is connected to an input end of the second optical splitter 214, and an output end of the second optical splitter 214 is connected to the second reflection-type hydrogen sensor 212.
The power compensation unit 22 performs power compensation on the plurality of reflection-type hydrogen sensors, the power compensation unit 22 includes a compensation light source 221, a third optical splitter 222 and a fourth optical splitter 223, an input end of the third optical splitter 222 is connected with the compensation light source 221, a first output end of the third optical splitter 222 is connected with the first reflection-type hydrogen sensor 211, a second output end of the third optical splitter 222 is connected with an input end of the fourth optical splitter 223, an output end of the fourth optical splitter 223 is connected with the second reflection-type hydrogen sensor 212, wherein the first optical splitter 213 and the third optical splitter 222 have the same splitting ratio, the second optical splitter 214 and the fourth optical splitter 223 have the same splitting ratio, and the first optical splitter 213 and the third optical splitter 222 are all 1×2 couplers. By adding the power compensation light source 221, power compensation of the reflection type hydrogen sensor is realized, and stability of the reflection type hydrogen sensor is improved.
Referring to fig. 3, the sensor array unit 21 may include a plurality of first reflective hydrogen sensors 211, a plurality of first optical splitters 213, and a second optical splitter 214, wherein two adjacent first reflective hydrogen sensors 211 are connected through the first optical splitters 213, the number of the first reflective hydrogen sensors 211 is equal to the number of the first optical splitters 213, and the number of the first reflective hydrogen sensors 211 is equal to the hydrogen concentration point-1 to be measured. The power compensation unit 22 may include a compensation light source 221, a third optical splitter 222 equal in number to the first optical splitter 213, and a fourth optical splitter 223, and the first optical splitter 213 and the third optical splitter 222 connected to the same first reflection type hydrogen sensor 211 have the same split ratio. The reflective hydrogen sensor needs to have similar operating power, and the operating power of the first reflective hydrogen sensor 211 and the second reflective hydrogen sensor 212 should satisfy 10 μw to 120 μw.
The sensor array unit 21 can replace the reflection-type hydrogen sensor independently, so that the replacement of the sensor is more convenient, meanwhile, the reflection-type hydrogen sensors are not interfered, and the reflection-type hydrogen sensors are flexibly distributed to meet various hydrogen monitoring scenes.
The sensing detection module 2 adjusts the beam splitting ratio of the optical splitters corresponding to the reflection-type hydrogen sensors based on a power uniform distribution algorithm, so that the beam splitting ratio of each beam splitter enables the signals distributed by each sensor to be uniform, wherein the sensing array unit 21 and the power compensation unit 22 are respectively provided with the optical splitters connected with each reflection-type hydrogen sensor correspondingly.
The sensing detection module 2 is composed of a series of reflective hydrogen sensors connected in series with optical splitters, and each optical splitter splits a part of light from a main optical fiber to act on each reflective hydrogen sensor. Through theoretical analysis, the power uniform distribution algorithm specifically comprises the following steps:
wherein ,the power allocated to each reflection-type hydrogen sensor is given in mW, ++>The light power of the pulse light is emitted after the sensing light source 11 is modulated by the semiconductor light amplifier 12, the unit is mW, the delta P sensing light source 11 emits light beam with fluctuating power in dBm +.>In order to reach the insertion loss of each stage of optical branching device before the nth reflection-type hydrogen sensor, the unit is dB, n is the number of the reflection-type hydrogen sensor, and the unit is ∈>For the self-loss of the optical fibers in the demodulation module 1 and the sensing detection module 2, the unit is dB/km, D is the distance between two adjacent reflection type hydrogen sensors, and the unit is km,/>The optical fiber fusion loss in the demodulation module 1 and the sensing detection module 2 is realized.
The application distributes the split ratio of the optical splitter corresponding to the reflection type hydrogen sensor in the sensing array unit 21 and the power compensation unit 22 through the power uniform distribution algorithm, and simultaneously, the power compensation unit 22 introduces continuous optical power compensation to carry out power compensation on the reflection type hydrogen sensor so as to improve the stability and the reaction speed of the reflection type hydrogen sensor.
For the reference light path, the expression of the optical power received by the first photodetector 17 is as follows:
wherein ,for the optical power received by the first photodetector 17, the unit is mW, r is the reflectivity of the reflective hydrogen sensor, +.>For the split ratio of the optical splitters at each level in the sensing detection module 2 +.>The optical fiber is used for sensing the self loss and fusion loss of the optical fiber in the detection module 2.
For the detection light path, since there is a certain fluctuation of the spontaneous emission light source, the fluctuation needs to be compensated, so the expression of the optical power received by the second photodetector 18 is as follows:
wherein ,for the optical power received by the second photodetector 18, in mW,/I>For the insertion loss of the fifth optical splitter 15, and (2)>Which is the fiber loss and splice loss in the demodulation module 1.
At this time, the upper computer can receive the optical power of the first photoelectric detector 17 and the second photoelectric detector 18 at the same time, and the upper computer performs further ratio processing on the optical power of the same group to obtain a ratio characteristic value, and reversely pushes out the concentration value of the hydrogen through the characteristic value so as to realize monitoring of the hydrogen concentration, wherein the first photoelectric detector 17 obtains the optical power of the reference optical path, and the second photoelectric detector 18 obtains the optical power of the detection optical path.
Specifically, the optical powers of the first photodetector 17 and the second photodetector 18 are divided, and since the optical pulse received by the reference optical path is the optical pulse causing each reflection type hydrogen sensor to reflect, that is, the divided two sets of power data are in the same pulse period, the fluctuation caused by the erbium-doped fiber amplifier 14 can be offset by the optical power ratio corresponding to the two optical paths, and the other quantity in the ratio is not changed with the change of time, so that an expression with only a single variable, that is, the reflectivity r of the reflection type hydrogen sensor is obtained. According to the characteristics of the reflection-type hydrogen sensor, the change of the hydrogen concentration of the reflection-type hydrogen sensor causes the change of the reflectivity of the reflection-type hydrogen sensor, so that the change of the hydrogen concentration of the atmosphere where the hydrogen sensor is positioned can be reversely deduced through the change of the optical power ratio obtained through calculation of the two optical paths. To more clearly describe the overall data processing process, the overall data processing process is shown in fig. 4.
After the upper computer receives the optical power ratio signals of the two optical paths, the hydrogen concentration needs to be reversely deduced from the optical power ratio signals. Firstly, each reflection-type hydrogen sensor in the sensing detection module 2 needs to be calibrated, each reflection-type hydrogen sensor is placed in a hydrogen concentration configurator, the concentration of hydrogen is changed, the variation of characteristic values of each reflection-type hydrogen sensor under each hydrogen concentration is obtained, then the response curve of each reflection-type hydrogen sensor under hydrogen with different concentrations is fitted, and the corresponding relation is written into an upper computer. When the hydrogen sensing system starts to work, the initial characteristic values of all the sensors are recorded, then the variation of the characteristic values of all the sensors is monitored in real time, and then the hydrogen concentration can be reversely deduced.
Referring to fig. 5, the abscissa of the graph shows the position number of the reflective hydrogen sensor, the ordinate shows the working power of the reflective hydrogen sensor, it can be seen that the two peak powers of the reflective hydrogen sensor are 48.5 μw and 52 μw respectively, the two valley powers of the reflective hydrogen sensor are 12.1 μw and 15.4 μw respectively, the power values of the rest detection positions float at 25 μw, and it can be approximately considered that the distributed working powers of the reflective hydrogen sensors are relatively uniform.
The foregoing description of the preferred embodiments of the application is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the application.
Claims (10)
1. An end face probe type quasi-distributed optical fiber hydrogen sensing system is characterized by comprising a demodulation module (1) and a sensing detection module (2), wherein the demodulation module (1) is connected with the sensing detection module (2),
the demodulation module (1) is used for receiving the optical signals returned by the sensing detection module (2) and converting the optical signals into electric signals so as to invert the hydrogen concentration detected by each reflection type hydrogen sensor;
the sensing detection module (2) comprises a sensing array unit (21) and a power compensation unit (22), wherein the sensing array unit (21) and the power compensation unit (22) are connected with the demodulation module (1), and the sensing array unit (21) is connected with the power compensation unit (22);
the sensing array unit (21) is used for acquiring optical signals corresponding to detection points of the reflection-type hydrogen sensors through the reflection-type hydrogen sensors, the power compensation unit (22) is used for performing power compensation on the reflection-type hydrogen sensors, the sensing detection module (2) is used for adjusting the light splitting ratio of the optical splitters corresponding to the reflection-type hydrogen sensors based on a power uniform distribution algorithm, and the sensing array unit (21) and the power compensation unit (22) are respectively provided with the optical splitters connected with the reflection-type hydrogen sensors.
2. The end-face probe type quasi-distributed optical fiber hydrogen sensing system according to claim 1, wherein the sensing array unit (21) comprises a first reflection type hydrogen sensor (211), a second reflection type hydrogen sensor (212), a first optical splitter (213) and a second optical splitter (214), an input end of the first optical splitter (213) is connected with the demodulation module (1), a first output end of the first optical splitter (213) is connected with the first reflection type hydrogen sensor (211), a second output end of the first optical splitter (213) is connected with an input end of the second optical splitter (214), and an output end of the second optical splitter (214) is connected with the second reflection type hydrogen sensor (212).
3. The end-face probe type quasi-distributed optical fiber hydrogen sensing system according to claim 2, wherein the power compensation unit (22) comprises a compensation light source (221), a third optical splitter (222) and a fourth optical splitter (223), an input end of the third optical splitter (222) is connected with the compensation light source (221), a first output end of the third optical splitter (222) is connected with the first reflection type hydrogen sensor (211), a second output end of the third optical splitter (222) is connected with an input end of the fourth optical splitter (223), and an output end of the fourth optical splitter (223) is connected with the second reflection type hydrogen sensor (212).
4. The end-face probe type quasi-distributed optical fiber hydrogen sensing system according to claim 1, wherein the demodulation module (1) comprises a sensing light source (11), a semiconductor optical amplifier (12), a signal emitter (13), an erbium-doped optical fiber amplifier (14), a fifth optical splitter (15), a circulator (16), a first photoelectric detector (17), a second photoelectric detector (18) and a data acquisition unit, wherein,
the sensing light source (11) is connected with the semiconductor optical amplifier (12), the semiconductor optical amplifier (12) is connected with the signal transmitter (13) and the erbium-doped fiber amplifier (14) respectively, the erbium-doped fiber amplifier (14) is connected with the fifth optical splitter (15), a first output end of the fifth optical splitter (15) is connected with a first port of the annular device (16), a second output end of the fifth optical splitter (15) is connected with the first photoelectric detector (17), a second port of the annular device (16) is connected with the sensing detection module (2), a third port of the annular device (16) is connected with the second photoelectric detector (18), and the data acquisition unit (19) is connected with the signal transmitter (13), the first photoelectric detector (17) and the second photoelectric detector (18) respectively.
5. The end-face probe type quasi-distributed optical fiber hydrogen sensing system according to claim 4, wherein the power uniform distribution algorithm is specifically:
；
wherein ,the power allocated to each of the reflection-type hydrogen sensors is +.>For the optical power of the pulse light emitted by the sensor light source (11) after being modulated by the semiconductor optical amplifier (12), the fluctuation power brought by the light beam emitted by the sensor light source (11) after being amplified by the erbium-doped optical fiber amplifier (14) is delta P>In order to reach the insertion loss of each stage of optical branching device before the nth reflection type hydrogen sensor, n is the number of the reflection type hydrogen sensor, +.>Is self-contained for the optical fibers in the demodulation module (1) and the sensing detection module (2)A body loss, D is the distance between two adjacent reflection type hydrogen sensors,the optical fiber fusion loss is generated in the demodulation module (1) and the sensing detection module (2).
6. The end-face probe type quasi-distributed optical fiber hydrogen sensing system according to claim 5, wherein the optical power expression received by the first photodetector (17) is:
；
wherein ,for the optical power received by the first photodetector (17), r is the reflectivity of the reflective hydrogen sensor, +.>For the split ratio of each level of optical splitters in the sensing detection module (2), the optical splitter is +.>Is the self-loss and fusion loss of the optical fiber in the sensing detection module (2).
7. The end-face probe-type quasi-distributed fiber optic hydrogen sensing system of claim 6, wherein the optical power expression received by the second photodetector (18) is:
；
wherein ,for the optical power received by the second photodetector (18), is +>For the insertion loss of the fifth optical splitter (15), is->Is the optical fiber loss and fusion loss in the demodulation module (1).
8. The end-face probe type quasi-distributed optical fiber hydrogen sensing system according to claim 4, wherein the fifth optical splitter (15) has a split ratio of 99:1, wherein a first output end of the fifth optical splitter (15) outputs 99% of optical signals, and a second output end of the fifth optical splitter (15) outputs 1% of optical signals.
9. An end-face probe type quasi-distributed optical fiber hydrogen sensing system according to claim 3, wherein said first optical splitter (213) and said third optical splitter (222) are each 1 x 2 couplers.
10. An end-face probe-type quasi-distributed optical fiber hydrogen sensing system according to claim 3, wherein the first optical splitter (213) and the third optical splitter (222) have the same splitting ratio, and the second optical splitter (214) and the fourth optical splitter (223) have the same splitting ratio.
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