CN219142650U - Optical fiber coupling gas sensing cavity and gas detection device - Google Patents

Optical fiber coupling gas sensing cavity and gas detection device Download PDF

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Publication number
CN219142650U
CN219142650U CN202223196661.5U CN202223196661U CN219142650U CN 219142650 U CN219142650 U CN 219142650U CN 202223196661 U CN202223196661 U CN 202223196661U CN 219142650 U CN219142650 U CN 219142650U
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optical fiber
signal acquisition
gas sensing
gas
receiving terminal
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董小鹏
杨镓华
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Xiamen University
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Xiamen University
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Abstract

The optical fiber coupled gas sensing cavity comprises a single-mode optical fiber, a single-mode optical fiber collimator, a first fixed pipe, a communicating pipe, a diffusion hole, a photoelectric detector and a second fixed pipe; the single-mode optical fiber is connected with the single-mode optical fiber collimator; the first fixing tube is sleeved and fixed with the single-mode fiber collimator; the communicating pipe is sleeved and fixed with the first fixed pipe; the communicating pipe is provided with a plurality of diffusion holes along the axial direction; the other end of the communicating pipe is sleeved and fixed with a second fixed pipe; the second fixing tube is sleeved and used for fixing the photoelectric detector; the photoelectric detector is provided with an anode pin and a cathode pin which are connected out by a lead. The gas detection device comprises a continuous light source, a signal acquisition system and a receiving terminal. The utility model directly couples the collimated laser and the photoelectric detector, thereby forming a complete light path, reducing the coupling difficulty of the sensing cavity and reducing the production and processing cost.

Description

Optical fiber coupling gas sensing cavity and gas detection device
Technical Field
The utility model relates to the field of optical fiber gas sensing detection, in particular to an optical fiber coupled gas sensing cavity and a gas detection device.
Background
Gas detection has been applied in various areas such as atmospheric monitoring, coal mines, urban pipelines, agricultural production, fire prevention, environmental protection, and the like. The existing gas sensor mainly comprises a semiconductor gas sensor, a solid electrolyte gas sensor, a contact combustion type gas sensor, an optical type gas sensor, a quartz resonance type gas sensor, a surface acoustic wave gas sensor and the like, wherein the gas sensor for measuring gas based on an optical principle has huge application potential because of the characteristics of weak cross interference, low complexity, low cost, strong multipoint sensing and non-contact remoteness.
Laser gas sensing technology based on tunable diode laser absorption spectroscopy (TDLAS, tunable Diode Laser Absorption Spectroscopy) has been widely commercialized in a variety of trace gas detection [1-4] due to its intrinsically safe, remotely monitorable advantage. However, in the conventional TDLAS single-point type laser gas sensing detection device, a laser is often required to be matched with a photoelectric detector, and after the optical paths are coupled, the laser is packaged as an independent gas detection probe, so that under the requirement of multi-point detection, a plurality of probes cause high cost, and a distribution circuit and signal processing are complex, so that the system is redundant. The coupling loss is usually small at short distance, but the sensitivity is low, and the coupling loss of the air chamber is usually high at long distance, and the collimator pair with a specific focal length needs to be customized to influence the final detected signal intensity. Furthermore, although solutions based on hollow fiber as a gas cell have been reported to successfully achieve distributed fiber gas measurement, the problems of expensive cost, complex processing, etc. have limited the applications [5,6].
Reference to the literature
[1]Norooz Oliaee,J.,et al.,Development of a Sub-ppb Resolution Methane Sensor Using aGaSb-Based DFB Diode Laser near 3270nm for Fugitive Emission Measurement.ACS Sensors,2022.7(2):p.564–572.
[2]Huang,A.,et al.,Frequency-division multiplexing and main peak scanning WMS method for TDLAS tomography in flame monitoring.IEEE Transactions on Instrumentation and Measurement,2020.69(11):p.9087–9096.
[3]Jiang,J.,et al.,TDLAS-based detection of dissolved methane in power transformer oil and field application.IEEE Sensors Journal,2018.18(6):p.2318–2325.
[4]Werle,P.,R.Mücke,and F.Slemr,The limits of signal averaging in atmospheric trace-gas monitoring by tunable diode-laser absorption spectroscopy(TDLAS).Applied Physics B,1993.57(2):p.131–139.Childs,P.R.,J.Greenwood,and C.Long,Review of temperature measurement.Review of scientific instruments,2000.71(8):p.2959-2978.
[5]Jin,W.,et al.,Gas detection with micro-and nano-engineered optical fibers.2013.19(6):p.741–759.
[6]Lin,Y.,et al.,Distributed gas sensing with optical fibre photothermal interferometry.Optics express,2017.25(25):p.31568–31585.
Disclosure of Invention
The utility model aims to solve the problems in the prior art and provide an optical fiber coupled gas sensing cavity and a gas detection device. The utility model designs a gas sensing cavity which can be simply coupled with an optical path, can be directly connected with a digital display after the sensing cavity according to the requirement, can be monitored in real time in the field, or can send the acquired signals to a terminal through wired or wireless transmission, and is flexible and convenient. In addition, the multiple sensing cavities can realize multiplexing of a single light source, which is beneficial to reducing the comprehensive cost of the multi-point gas monitoring system and has important application value.
In order to achieve the above purpose, the utility model adopts the following technical scheme:
the optical fiber coupled gas sensing cavity comprises a single-mode optical fiber, a single-mode optical fiber collimator, a first fixed pipe, a communicating pipe, a diffusion hole, a photoelectric detector and a second fixed pipe; the single-mode optical fiber is connected with the single-mode optical fiber collimator; the first fixing tube is sleeved and fixed with the single-mode fiber collimator; the communicating pipe is sleeved and fixed with the first fixed pipe; the communicating pipe is provided with a plurality of diffusion holes along the axial direction; the other end of the communicating pipe is sleeved and fixed with a second fixed pipe; the second fixing tube is sleeved and used for fixing the photoelectric detector; the photoelectric detector is provided with an anode pin and a cathode pin, and can be connected out by a lead.
In the utility model, the specific positions of the single-mode fiber collimator and the photoelectric detector in the communicating pipe are required to be finely adjusted after being coupled through the optical path, and the specific operation is that after a light source passes through the single-mode fiber collimator, the voltage among pins of the photoelectric detector is detected, the position is adjusted, and when the voltage reaches the maximum, the optical path coupling process is completed.
The first fixing tube may be made of glass.
The communicating tube may be stainless steel.
The diffusion holes are used for accelerating the exchange of gas inside and outside the communicating pipe, and can be formed by laser cutting at certain distance along the axial direction of the communicating pipe.
The second fixing tube may be made of glass.
A gas detection device comprises a continuous light source, a signal acquisition system, a receiving terminal and a gas sensing cavity; the continuous light source is connected with a single-mode optical fiber of the gas sensing cavity, the signal acquisition system is connected with a photoelectric detector of the gas sensing cavity, and the receiving terminal is connected with the signal acquisition system.
A multipoint gas detection device comprises a continuous light source, an optical fiber branching device, a plurality of gas sensing cavities, a plurality of signal acquisition systems and a receiving terminal; the continuous light source is connected with the single mode optical fibers of the plurality of gas sensing cavities through the optical fiber branching device, the plurality of signal acquisition systems are respectively and correspondingly connected with the photoelectric detectors of the plurality of gas sensing cavities, and the receiving terminal is connected with the signal acquisition systems.
The optical fiber splitter can be selected according to the actual measurement point number, including but not limited to a 1-division-4 optical fiber splitter, a 1-division-8 optical fiber splitter, a 1-division-16 optical fiber splitter and the like.
The signal acquisition system can be a signal acquisition card, and is directly connected to the receiving terminal in a wired manner through the electric signal after receiving the photoelectric detector to perform signal processing analysis, and can also wirelessly transmit the signal to the receiving terminal through the wireless transmission module to perform signal processing analysis.
The receiving terminal may be a computer.
Compared with the prior art, the technical scheme of the utility model has the beneficial effects that:
1. the single-mode optical fiber is connected with the single-mode optical fiber collimator; the first fixing tube is sleeved and fixed with the single-mode fiber collimator; the communicating pipe is sleeved and fixed with the first fixed pipe; the communicating pipe is provided with a plurality of diffusion holes along the axial direction; the other end of the communicating pipe is sleeved and fixed with a second fixed pipe; the second fixing tube is sleeved and used for fixing the photoelectric detector; the photoelectric detector is provided with an anode pin and a cathode pin, and can be connected out by a lead, and the collimated laser is directly coupled with the photoelectric detector, so that a complete light path is formed, the coupling difficulty of a sensing cavity is reduced, and the production and processing cost is reduced.
2. The optical fiber coupled gas sensing cavity can be directly connected with a digital display after the gas sensing cavity according to the requirement, can be monitored in real time in the field, or can be used for transmitting the acquired signals to a terminal through wired or wireless transmission, is flexible and convenient, and is beneficial to realizing diffusion type gas detection through the design of a plurality of diffusion holes.
3. The utility model can only use one continuous laser light source, can distribute the multi-path optical fiber gas sensing probe to detect the gas through the optical fiber branching device, and then can obtain the gas signals of a plurality of position points by the multi-path signal acquisition system.
Drawings
Fig. 1 is a schematic overall structure of embodiment 1.
Fig. 2 is a schematic overall structure of embodiment 2.
Reference numerals: 1-a continuous light source; 2-single mode optical fiber; a 3-single mode fiber collimator; 4-a first fixed tube; 5-communicating pipe; 6-diffusion holes; 7-a photodetector; 8-a second fixed tube; 9-a signal acquisition system; 10-a receiving terminal; 11-a first gas sensing chamber; 12-a second gas sensing chamber; 13-a third gas sensing chamber; 14-a fourth gas sensing chamber; 15-an optical fiber splitter; 901-a first signal acquisition system; 902-a second signal acquisition system; 903—a third signal acquisition system; 904-fourth signal acquisition system.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved more clear and obvious, the utility model is further described in detail below with reference to the accompanying drawings and embodiments.
Example 1
Referring to fig. 1, an optical fiber coupled gas sensing cavity and a gas detection device are provided, which comprise a continuous light source 1, a single-mode optical fiber 2, a single-mode optical fiber collimator 3, a first fixed tube 4, a communicating tube 5, a diffusion hole 6, a photoelectric detector 7, a second fixed tube 8, a signal acquisition system 9 and a receiving terminal 10;
the single-mode fiber 2 is connected with a single-mode fiber collimator 3; the first fixing tube 4 is sleeved and used for fixing the single-mode fiber collimator 3; the communicating pipe 5 is sleeved and fixed on the first fixed pipe 4; the communicating pipe 5 is provided with a plurality of diffusion holes 6 along the axial direction; the other end of the communicating pipe 5 is sleeved with and fixed with a second fixed pipe 8; the second fixing tube 8 is sleeved and used for fixing the photoelectric detector 7; the photoelectric detector 7 is provided with an anode pin 701 and a cathode pin 702 which can be connected out by a lead; the continuous light source 1 is connected with the single-mode optical fiber 2, the signal acquisition system 9 is connected with the photoelectric detector 7, and the receiving terminal 10 is connected with the signal acquisition system 9.
The specific positions of the single-mode fiber collimator 3 and the photoelectric detector 7 in the communicating pipe 5 need to be finely adjusted after being coupled through an optical path, and the specific operation is that after a light source passes through the single-mode fiber collimator 3, the voltage among pins of the photoelectric detector 7 is detected, the position is adjusted, and when the voltage reaches the maximum, the optical path coupling process is completed.
The outer diameter of the single-mode fiber 2 is 125-126 mu m, and the fiber core diameter is 9-10 mu m.
The single-mode fiber collimator 3 is used for collimating and transmitting laser entering from the single-mode fiber into the photoelectric detector 7, and the outer diameter of the single-mode fiber collimator 3 is 2.78mm, and the length is 10mm.
The first fixing pipe 4 is made of glass, the outer diameter is 5mm, the inner diameter is 3mm, and the length is 10mm.
The communicating pipe 5 is made of stainless steel, has an outer diameter of 5.5mm, an inner diameter of 4.9mm and a length of 120mm, and in other embodiments, the outer diameter, the inner diameter and the length of the communicating pipe are not particularly limited, and can be specifically set according to actual requirements.
The diffusing holes 6 are used for accelerating the gas exchange inside and outside the communicating pipe, and 4 face holes can be drilled at intervals of 10mm along the axial direction of the communicating pipe by laser cutting, the aperture is 2mm, the intervals, the face number and the aperture size of the diffusing holes in other embodiments are not particularly limited, and the diffusing holes can be specifically set according to actual requirements.
The second fixing tube 8 is made of glass, has an inner diameter of 4.7mm, an outer diameter of 4.9mm and a length of 10mm.
The photodetector 7 is an InGaSn-type PIN photodiode, the response wavelength range is 1100-1650 nm, the optical responsivity is 0.85A/W, the bandwidth is 3GHz, the maximum outer diameter is 4.6mm, and the outer diameter size in other embodiments is not particularly limited, and specifically can be set according to actual requirements.
The working principle of the optical fiber coupled gas sensing cavity of the embodiment is as follows:
after gas is diffused into the communicating pipe 5 through the diffusion hole 6, after being collimated by the single-mode fiber collimator 3 and acted with target gas, the interaction between light and gas can generate absorption phenomenon according to the beer-lambert law, and generally, under the unsaturated absorption condition, the incident light intensity and the transmitted light intensity have the following relationship:
I out(ν) ＝I in(ν) exp(-α v CL)
wherein alpha is v Is the gas absorption coefficient, unit cm -1 L represents the effective absorption optical path of the gas in cm; c represents the volume percent of the gas in ppm; i in(ν) Light intensity before inputting gas sample for laser with wavelength v, I out(ν) Light intensity after inputting the gas sample for the laser of wavelength v.
The light intensity change after gas absorption can be converted into a voltage signal by the photodetector 7 and processed by a subsequent detection system.
In this embodiment, the continuous light source 1 is a near infrared wavelength tunable laser capable of being coupled to a single mode fiber, and the center wavelength is matched with the absorption peak wavelength of the target gas as required, specifically, a semiconductor Distributed Feedback (DFB) laser with a wavelength of 1653nm, so as to realize the detection of methane gas;
the signal acquisition system 9 is a signal acquisition card, the sampling bit number is 8, the sampling channel number is 4, and the maximum sampling rate single channel is 1GHz. The signal acquisition system 9 is not limited to a wired signal acquisition card, and may be, for example, a wireless transmission module, and is not particularly limited. The receiving terminal 10 employs a computer.
The working principle of the collecting device of the embodiment is as follows:
the continuous light source 1 is turned on, laser enters the single-mode fiber collimator 3 through the single-mode fiber 2, is collimated by the single-mode fiber collimator 3 and enters the communicating pipe 5, receives optical signals by the photoelectric detector 7, converts the optical signals into electric signals, and sends the electric signals to the receiving terminal 10 for signal processing through a wired transmission mode or a wireless transmission mode after the electric signals are collected by the signal collecting system 9. Obtaining a concentration-voltage curve by changing the concentration of the target gas injected into the communicating tube 5; in actual measurement, the concentration of the target gas in the fiber-coupled gas chamber is back calculated from the voltage-concentration curve.
Example 2
Referring to fig. 2, the present embodiment is a multi-point gas detection device, which includes a continuous light source 1, an optical fiber splitter 15, a first gas sensing chamber 11, a second gas sensing chamber 12, a third gas sensing chamber 13, a fourth gas sensing chamber 14, a first signal acquisition system 901, a second signal acquisition system 902, a third signal acquisition system 903, a fourth signal acquisition system 904, and a receiving terminal 10; the continuous light source 1 is connected with an optical fiber branching device 15; the optical fiber branching device 15 is respectively connected with the first gas sensing cavity 11, the second gas sensing cavity 12, the third gas sensing cavity 13 and the fourth gas sensing cavity 14;
the first gas sensing cavity 11, the second gas sensing cavity 12, the third gas sensing cavity 13 and the fourth gas sensing cavity 14 are respectively connected with the first signal acquisition system 901, the second signal acquisition system 902, the third signal acquisition system 903 and the fourth signal acquisition system 904;
the first signal acquisition system 901, the second signal acquisition system 902, the third signal acquisition system 903, and the fourth signal acquisition system 904 may be signal acquisition cards, and the electrical signals after receiving the photodetectors are directly wired to the receiving terminal 10 for signal processing analysis, or the signals may be wirelessly transmitted to the receiving terminal 10 via a wireless transmission module for signal processing analysis.
The optical fiber branching device is a 1-way and 4-way optical fiber branching device, the insertion loss is less than or equal to 0.3dB, the scheme is not limited, and 1-way and 8-way, 1-way and 16-way and the like can be selected according to the actual measurement point number.
In this embodiment, only one continuous laser light source can be used, multiple optical fiber gas sensing probes can be distributed through an optical fiber branching device to perform gas detection, then multiple data acquisition systems can obtain gas signals of multiple position points, compared with the scheme that multiple probes need to be matched with multiple laser light sources in the past, the cost is greatly reduced, the reliability and stability of the system are reserved through an optical gas detection method, and a scheme with great competitiveness is provided for further expanding application scenes.
The above description is only of the preferred embodiments of the present utility model and is not intended to limit the present utility model, but various modifications and variations can be made to the present utility model by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model should be included in the protection scope of the present utility model.

Claims (10)

1. An optical fiber coupled gas sensing chamber, characterized in that: the device comprises a single-mode fiber, a single-mode fiber collimator, a first fixed pipe, a communicating pipe, a diffusion hole, a photoelectric detector and a second fixed pipe; the single-mode optical fiber is connected with the single-mode optical fiber collimator; the first fixing tube is sleeved and fixed with the single-mode fiber collimator; the communicating pipe is sleeved and fixed with the first fixed pipe; the communicating pipe is provided with a plurality of diffusion holes along the axial direction; the other end of the communicating pipe is sleeved and fixed with a second fixed pipe; the second fixing tube is sleeved and used for fixing the photoelectric detector; the photoelectric detector is provided with an anode pin and a cathode pin which are connected out by a lead.
2. An optical fiber coupled gas sensing chamber as defined in claim 1, wherein: the first fixing tube and the second fixing tube are made of glass materials.
3. An optical fiber coupled gas sensing chamber as defined in claim 1, wherein: the communicating pipe is made of stainless steel.
4. An optical fiber coupled gas sensing chamber as defined in claim 1, wherein: the diffusion holes are cut by laser.
5. A gas detection device, characterized in that: the optical fiber coupling type gas sensing cavity comprises a continuous light source, a signal acquisition system and a receiving terminal, and further comprises the optical fiber coupling type gas sensing cavity according to any one of claims 1-4; the continuous light source is connected with a single-mode optical fiber of the gas sensing cavity, the signal acquisition system is connected with a photoelectric detector of the gas sensing cavity, and the receiving terminal is connected with the signal acquisition system.
6. A gas detection apparatus according to claim 5, wherein: the signal acquisition system adopts a signal acquisition card, and is directly connected to a receiving terminal in a wired manner through an electric signal after receiving the photoelectric detector for signal processing analysis, or the signal acquisition system wirelessly transmits signals to the receiving terminal through a wireless transmission module for signal processing analysis.
7. A gas detection apparatus according to claim 5, wherein: the receiving terminal adopts a computer.
8. A gas detection device, characterized in that: the optical fiber sensor comprises a continuous light source, an optical fiber branching device, a plurality of gas sensing cavities, a plurality of signal acquisition systems and a receiving terminal, wherein the gas sensing cavities are optical fiber coupled gas sensing cavities according to any one of claims 1-4; the continuous light source is connected with the single mode optical fibers of the plurality of gas sensing cavities through the optical fiber branching device, the plurality of signal acquisition systems are respectively and correspondingly connected with the photoelectric detectors of the plurality of gas sensing cavities, and the receiving terminal is connected with the signal acquisition systems.
9. A gas detection apparatus as defined in claim 8, wherein: the signal acquisition system adopts a signal acquisition card, and is directly connected to a receiving terminal in a wired manner through an electric signal after receiving the photoelectric detector for signal processing analysis, or the signal acquisition system wirelessly transmits signals to the receiving terminal through a wireless transmission module for signal processing analysis.
10. A gas detection apparatus as defined in claim 8, wherein: the optical fiber branching devices are selected according to the actual measurement points and comprise 1-division-4 optical fiber branching devices, 1-division-8 optical fiber branching devices and 1-division-16 optical fiber branching devices; the receiving terminal adopts a computer.
CN202223196661.5U 2022-11-30 2022-11-30 Optical fiber coupling gas sensing cavity and gas detection device Active CN219142650U (en)

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