Multi-component gas laser synchronous detection system and method

Abstract

The invention discloses a multi-component gas laser synchronous detection system and method, and belongs to the technical field of laser spectrum gas detection. According to the invention, the corresponding absorption peak position is obtained through the concentrations of CH4, H2S, O2 and CO standard gases in the multi-component sealed gas pool, and the laser driving module is regulated in real time to lock the central wavelength output by the corresponding laser module; a laser driving module synchronously outputs CH4 and H2S analog voltage signals in the same direction and O2 and CO analog voltage signals in the reverse direction to drive a corresponding CH4 laser, a H2S laser, an O2 laser and a CO laser, paired analog voltage signals in opposite directions can be synchronously output, and modulation amplitudes of current modulation signals of the four lasers are mutually counteracted when gas to be detected is detected. And meanwhile, absorption signal positions of the four gases can be arranged at strong light intensity positions, so that the amplitude values and the signal-to-noise ratios of the absorption signals of the four gases are remarkably improved, and the synchronous absorption detection precision of the four gases is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of laser spectrum gas detection, in particular to a multi-component gas laser synchronous detection system and method. Background Art

[0002] In the scenario of multi-component gas detection using tuned laser absorption spectroscopy (TDLAS), current implementations usually involve the use of multiple lasers, each laser specifically corresponding to a specific gas component. The choice of this method is based on the absorption characteristics of different gas components, where each component shows a strong absorption line at a specific wavelength, so the selection of the appropriate laser wavelength is crucial to improving the accuracy of detection. In the use of tuned laser absorption spectroscopy (TDLAS) technology for multi-component gas detection, a major challenge is how to effectively detect the optical signal of the required laser with significant wavelength differences. Although the system can choose to use a photodetector that covers a wide wavelength range, such a detector usually introduces high system noise, which is unacceptable for high-precision detection. Therefore, in order to ensure the high-precision performance of the detection process, the system must be equipped with multiple dedicated photodetectors to accurately respond to laser signals of different wavelengths. Although this approach increases the complexity and cost of the system, it can significantly improve the accuracy and reliability of detection and meet the strict requirements of high-precision monitoring.

[0003] Multi-component gas detection methods are mainly divided into synchronous detection and asynchronous detection. Asynchronous detection technology refers to monitoring different gas components at different time points. This method is suitable for applications where time synchronization is not required, or where there are restrictions on equipment cost and maintenance. Synchronous detection is often accompanied by an increase in equipment cost because multiple photodetectors and signal processing channels are required, but it has fast time response and excellent time accuracy. Therefore, in application scenarios that require high detection time accuracy, such as combustion diagnosis, natural gas leak monitoring, and coal mine safety, which require real-time online monitoring, synchronous detection solutions are more in line with demand. Summary of the invention

[0004] In view of the above problems, a multi-component gas laser synchronous detection system and method are provided. The present invention obtains the corresponding absorption peak position through the CH4, H2S, O2, CO standard gas concentrations in the multi-component sealed gas pool, and controls the laser driving module in real time to lock the central wavelength output by the corresponding laser module; the laser driving module synchronously outputs the same-direction CH4 and H2S analog voltage signals and the reverse O2 and CO analog voltage signals to drive the corresponding CH4 laser, H2S laser, O2 laser, and CO laser, and can synchronously output paired analog voltage signals in opposite directions. When detecting the gas to be tested, the modulation amplitudes of the four laser current modulation signals offset each other, which can greatly improve the signal amplification factor. At the same time, the absorption signal positions of the four gases can be set at the position of strong light intensity, so that the amplitude values ​​and signal-to-noise ratios of the absorption signals of the four gases are significantly improved, thereby further improving the absorption detection accuracy of the four gases.

[0005] To achieve the above object, the technical solution adopted by the present invention is.

[0006] A multi-component gas laser synchronous detection system comprises a signal processing module, a laser driving module for outputting four different modulation signals, a laser module for outputting four different wavelength detection lasers, a beam combiner, a beam splitter, a multi-component sealed gas pool, a wide-range photoelectric detector for detecting and responding to four wavelength spectrum ranges, a multiple reflection pool, a first polarization beam splitter prism, a second polarization beam splitter prism, a first photoelectric detector, a second photoelectric detector and a third photoelectric detector; the laser driving module comprises a first co-directional amplifier circuit, a CH4 laser driving module, a second co-directional amplifier circuit, an H2S laser driving module, a first reverse amplifier circuit, an O2 laser driving module, a second reverse amplifier circuit and a CO laser driving module. The signal processing module outputs a digital-analog voltage signal, which is synchronously amplified in the same direction and reversely amplified by the same-direction amplifier 1, the same-direction amplifier 2 and the reverse amplifier 1, the reverse amplifier 2, and then respectively input into the corresponding CH4 laser driving module, the H2S laser driving module, the O2 laser driving module, and the CO laser driving module, and synchronously outputs the same-direction CH4 and H2S analog voltage signals and the reverse O2 and CO analog voltage signals to drive the corresponding CH4 laser, the H2S laser, the O2 laser, and the CO laser, and finally outputs four detection lasers with different wavelengths, which are coupled by the beam combiner and output to the beam splitter, and are split into measurement signals and reference signals by the beam splitter.

[0007] Preferably, the reference signal is sequentially output to the signal processing module after passing through a multi-component sealed gas pool and a wide-band photoelectric detector. The signal processing module demodulates to obtain the absorption peak positions corresponding to the CH4, H2S, O2, and CO standard gas concentrations in the multi-component sealed gas pool and outputs them to the laser driving module to feedback and control the laser driving module to output four different modulation signals, and finally lock the central wavelength output by the corresponding laser module; the measurement signal is sequentially output to polarization beam splitter prism 1 and polarization beam splitter prism 2 after being absorbed by the gas to be measured in the multiple reflection pool, and is respectively received by photodetector 1, photodetector 2, and photodetector 3 after being split by the polarization beam splitter prism 1 and the polarization beam splitter prism 2 and converted into photocurrent signals. The photocurrent signals are combined and output to the signal processing module, and the signal processing module calculates the CH4, H2S, O2, and CO gas concentration values ​​of the gas to be measured according to the multi-component gas laser synchronous detection method and the Lambert-Beer gas absorption theorem.

[0008] Preferably, the splitting ratio of the measurement signal to the reference signal is 9:1.

[0009] Preferably, the interior of the multi-component sealed gas pool is divided into four groups of independent small gas pools of equal width connected in series.

[0010] Preferably, the four groups of independent small gas pools are respectively provided with CH4, H2S, O2, and CO gases of standard gas concentrations.

[0011] Preferably, the signal processing module includes a reference signal processing module, an MCU, a measurement signal processing module and a DAC.

[0012] Preferably, after the reference signal is absorbed by four groups of standard concentration gases in a multi-component sealed gas pool, the reference signal is converted into a photocurrent signal by a wide-range photodetector and then output to a reference signal processing module, which is converted into a reference voltage signal by the reference signal processing module and then output to an MCU. The MCU demodulates to obtain the absorption peak positions corresponding to the four standard gas concentrations and outputs them to a DAC, which converts the absorption peak position output into a digital-analog voltage signal to drive a laser driving module to lock the central wavelength output by the corresponding laser module.

[0013] Preferably, the photocurrent signals are combined and output to a measurement signal processing module, which converts them into measurement voltage signals and outputs them to an MCU, which calculates the CH4, H2S, O2, and CO gas concentration values ​​of the gas to be measured.

[0014] Preferably, the Lambert-Beer gas absorption theorem is as follows: in, I 0 is the incident light intensity, It is the transmitted light intensity, α ( ν ) is the absorbance, k ν is the spectral absorption coefficient, S (T) is the temperature-dependent absorption line intensity, ϕ( ν ) is the normalized absorption line function, P is the pressure, X is the concentration of the gas, and L is the absorption path length, which is the optical path length in the multiple reflection cell.

[0015] A multi-component gas laser synchronous detection method comprises the following steps: Step 1: After being driven by the same-direction CH4 and H2S analog voltage signals and the reverse-direction O2 and CO analog voltage signals, the CH4 laser, the H2S laser, the O2 laser, and the CO laser respectively output four different wavelength detection lasers. The modulation signals corresponding to the four different wavelength detection lasers are as follows: Among them, U1, U2, U3 and U4 are the current modulation signals of CH4 laser, H2S laser, O2 laser and CO laser respectively; a1, a2, a3 and a4 are the bias currents corresponding to the four laser current modulation signals respectively; b1, b2, b3 and b4 are the modulation amplitudes of the four laser current modulation signals respectively; Step 2: The four different wavelength detection lasers are coupled by a beam combiner and output to a beam splitter, and are split into a measurement signal and a reference signal by the beam splitter; the reference signal is sequentially output to a signal processing module after passing through a multi-component sealed gas pool and a wide-range photoelectric detector, and the signal processing module demodulates to obtain the absorption peak position corresponding to the CH4, H2S, O2, and CO standard gas concentrations in the multi-component sealed gas pool and outputs it to a laser driving module, so as to feedback and regulate the laser driving module to output four different modulation signals, and finally lock the central wavelength output by the corresponding laser module; Step 3: The measurement signal after being absorbed by the gas to be measured in the multiple reflection pool is: in, , , and They are the absorption signals of CH4, H2S, O2 and CO respectively; Step 4: The measurement signals absorbed by the gas to be measured in the multiple reflection pool are output to polarization beam splitter prism 1 and polarization beam splitter prism 2 in sequence, and are received by photodetector 1, photodetector 2 and photodetector 3 respectively after being split by polarization beam splitter prism 1 and polarization beam splitter prism 2 and converted into photocurrent signals. The converted photocurrent signals I1, I2 and I3 are as follows: Step 5: The photocurrent signals are combined and output to the measurement signal processing module. The current signal I output after the combination is: Step 6: The measurement signal processing module converts the combined current signal in step 5 into a measurement voltage signal V after current isolation: At this time, the modulation amplitudes b1, b2, b3 and b4 of the four laser current modulation signals cancel each other out; Step 7: The measured voltage signal V in step 6 is output to the MCU, which calculates the CH4, H2S, O2 and CO gas concentration values ​​of the measured gas according to the Lambert-Beer gas absorption theorem.

[0016] Due to the adoption of the above technical solution, the present invention has the following beneficial effects.

[0017] (1) The present invention obtains the corresponding absorption peak position through the standard gas concentrations of CH4, H2S, O2, and CO in the multi-component sealed gas pool, and adjusts the laser driving module in real time to lock the central wavelength output by the corresponding laser module, thereby ensuring the stability of the laser synchronous output of four different central wavelengths. At the same time, the introduced system noise can be eliminated in real time, ensuring the stability, synchronization and accuracy of the multi-component gas laser synchronous detection.

[0018] (2) The present invention drives the corresponding CH4 laser, H2S laser, O2 laser, and CO laser by synchronously outputting the same-direction CH4 and H2S analog voltage signals and the reverse O2 and CO analog voltage signals through the laser driving module, and can synchronously output pairs of analog voltage signals in opposite directions. When detecting the gas to be tested, the modulation amplitudes of the four laser current modulation signals cancel each other out, which can greatly increase the signal amplification factor, thereby increasing the amplitude value and signal-to-noise ratio of each gas absorption signal, and ultimately achieving the purpose of improving the synchronous detection accuracy of the gas. In addition, due to the use of synchronous laser modulation in the same direction and reverse direction, the absorption signal positions of the four gases can be set at the position of strong light intensity, so that the amplitude value and signal-to-noise ratio of the absorption signals of the four gases are significantly improved, thereby further improving the absorption detection accuracy of the four gases.

[0019] (3) The present invention converts the digital signal output by the MCU into an analog voltage signal through a DAC, i.e., a digital-to-analog converter, and drives four lasers at the same time, which has good synchronous detection performance, avoids signal loss and delay caused by multiple conversions, and improves the overall stability and response speed of the system. In addition, the present invention couples four wavelengths of laser light into one beam and uses a dedicated photodetector to improve the device integration and ease of operation, reduce the size of the device, and simplify the installation and maintenance process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The following is a detailed discussion of the making and application of the preferred embodiments of the present invention. However, it should be understood that the present invention provides many applicable inventive concepts that can be embodied in various specific environments. The specific embodiments discussed are only for the purpose of illustrating the specific ways of making and using the present invention, and do not limit the scope of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative work.

[0021] Figure 1 It is a structural diagram of the present invention.

[0022] Figure 2 This is a position diagram of the four gas absorption peaks of the present invention.

[0023] Figure 3 A signal diagram is used for the superposition of the present invention.

[0024] Among them, 1-MCU, 2-reference signal processing module, 3-co-directional amplifier circuit 1, 4-reverse amplifier circuit 1, 5-reverse amplifier circuit 2, 6-co-directional amplifier circuit 2, 7-CH4 laser driver module, 8-O2 laser driver module, 9-CO laser driver module, 10-H2S laser driver module, 11-measurement signal processing module, 12-CH4 laser, 13-O2 laser, 14-CO laser, 15-H2S laser, 16-beam combiner, 17-beam splitter, 18-multi-component sealed gas cell, 19-wide-range photodetector, 20-multiple reflection cell, 21-photodetector 3, 22-polarization beam splitter prism 2, 23-polarization beam splitter prism 1, 24-photodetector 2, 25-photodetector 1. DETAILED DESCRIPTION

[0025] The following is a detailed discussion of the making and application of the preferred embodiments of the present invention. However, it should be understood that the present invention provides many applicable inventive concepts that can be embodied in various specific environments. The specific embodiments discussed are only intended to illustrate specific ways to make and use the present invention and do not limit the scope of the present invention.

[0026] The present invention converts the digital signal output by MCU1 into an analog voltage signal through a DAC, i.e., a digital-to-analog converter, and drives four lasers at the same time, having good synchronous detection performance, while avoiding signal loss and delay caused by multiple conversions, and improving the overall stability and response speed of the system. In addition, the present invention couples four wavelengths of laser light into one beam and cooperates with a dedicated photodetector, which improves the device integration and operation convenience, reduces the device size, and simplifies the installation and maintenance process.

[0027] The following is combined with Figure 1-3 Further elaboration. Example 1

[0028] like Figure 1The multi-component gas laser synchronous detection system includes a signal processing module, a laser driving module for outputting four different modulation signals, a laser module for outputting four different wavelength detection lasers, a beam combiner 16, a beam splitter 17, a multi-component sealed gas pool 18, a wide-range photodetector 19 for detecting and responding to four wavelength spectrum ranges, a multiple reflection pool 20, a polarization beam splitter prism 1 23, a polarization beam splitter prism 2 22, a photodetector 1 25, a photodetector 2 24 and a photodetector 3 21; the laser driving module includes a co-directional amplifier circuit 1 3, a CH4 laser driving module 7, a co-directional amplifier circuit 2 6, an H2S laser driving module 10, a reverse amplifier circuit 1 4, an O2 laser driving module 8, a reverse amplifier circuit 2 5 and a CO laser driving module 9. The signal processing module includes a reference signal processing module 2, an MCU1, a measurement signal processing module 11 and a DAC. The signal processing module outputs a digital-analog voltage signal, which is synchronously amplified in the same direction and reversely amplified by the same-direction amplifier 1, the same-direction amplifier 2, and the reverse amplifier 1, the reverse amplifier 2, and then input into the corresponding CH4 laser driving module 7, the H2S laser driving module 10, the O2 laser driving module 8, and the CO laser driving module 9, and synchronously outputs the same-direction CH4 and H2S analog voltage signals and the reverse O2 and CO analog voltage signals to drive the corresponding CH4 laser 12, the H2S laser 15, the O2 laser 13, and the CO laser 14, and finally outputs four different wavelength detection lasers. The four different wavelength detection lasers are coupled by the beam combiner 16 and output to the beam splitter 17, and are split into measurement signals and reference signals by the beam splitter 17, and the splitting ratio of the measurement signal and the reference signal is 9:1.

[0029] The present invention drives the corresponding CH4 laser 12, H2S laser 15, O2 laser 13, and CO laser 14 by synchronously outputting the same direction CH4 and H2S analog voltage signals and the reverse O2 and CO analog voltage signals through the laser driving module, and can synchronously output the paired analog voltage signals in opposite directions. When detecting the gas to be measured, the modulation amplitudes of the four laser current modulation signals cancel each other out, which can greatly improve the signal amplification factor, thereby improving the amplitude value and signal-to-noise ratio of each gas absorption signal, and finally achieving the purpose of improving the synchronous detection accuracy of the gas. In addition, due to the use of the same direction and reverse synchronous laser modulation, the absorption signal positions of the four gases can be set at the position of strong light intensity, so that the amplitude value and signal-to-noise ratio of the absorption signals of the four gases are significantly improved, thereby further improving the absorption detection accuracy of the four gases.

[0030] After the reference signal is absorbed by the four groups of standard concentration gases in the multi-component sealed gas pool 18, the reference signal is converted into a photocurrent signal by the wide-area photodetector 19 and then output to the reference signal processing module 2. After being converted into a reference voltage signal by the reference signal processing module 2, it is output to MCU1. The MCU1 demodulates to obtain the absorption peak positions corresponding to the four standard gas concentrations and outputs them to the DAC. The DAC converts the absorption peak position output into a digital-analog voltage signal to drive the laser driving module to lock the central wavelength output by the corresponding laser module. The position diagram of the four gas absorption peaks of the present invention is shown in FIG. Figure 2 The multi-component sealed gas pool 18 is divided into four groups of independent small gas pools of equal width in series, and the four groups of independent small gas pools are provided with CH4, H2S, O2, and CO gases of standard gas concentrations in sequence.

[0031] The present invention obtains the corresponding absorption peak position through the CH4, H2S, O2, and CO standard gas concentrations in the multi-component sealed gas pool 18, and real-time adjusts the laser driving module to lock the central wavelength output by the corresponding laser module, thereby ensuring the stability of the laser synchronously outputting four different central wavelength detections, and at the same time, can eliminate the introduced system noise in real time, thereby ensuring the stability, synchronization and accuracy of the multi-component gas laser synchronous detection.

[0032] The measurement signal is absorbed by the gas to be measured in the multiple reflection pool 20 and is output to the polarization beam splitter prism 1 23 and the polarization beam splitter prism 2 22 in sequence. After being split by the polarization beam splitter prism 1 23 and the polarization beam splitter prism 2 22, it is received by the photodetector 1 25, the photodetector 2 24 and the photodetector 3 21 and converted into photocurrent signals respectively. The photocurrent signals are combined and output to the measurement signal processing module 11. After being converted into a measurement voltage signal by the measurement signal processing module 11, it is output to MCU1. MCU1 calculates the CH4, H2S, O2 and CO gas concentration values ​​of the gas to be measured according to the multi-component gas laser synchronous detection method and the Lambert-Beer gas absorption theorem.

[0033] The Lambert-Beer gas absorption theorem is as follows: in, I 0 is the incident light intensity, I t is the transmitted light intensity, α ( ν ) is the absorbance, k ν is the spectral absorption coefficient, S (T) is the temperature-dependent absorption line intensity, ϕ( ν ) is the normalized absorption line function, P is the pressure, X is the concentration of the gas, and L is the absorption optical path, that is, the optical path length in the multiple reflection cell 20.

[0034] The signal converted by a DAC, or digital-to-analog converter, can modulate and drive four different lasers at the same time, reducing the hardware resource requirements while ensuring the synchronization of the four-way modulated signals. The main advantage of this design is that it efficiently utilizes the DAC conversion process, avoids signal loss and delay caused by multiple conversions, and improves the overall stability and response speed of the system. This method not only optimizes the laser driving scheme, but also helps to improve the performance and reliability of the equipment. In order to effectively detect the optical signal of the required laser with significant wavelength differences, and to ensure the high-precision performance of the detection process, the system is equipped with multiple dedicated photodetectors, which accurately respond to laser signals of different wavelengths.

[0035] After the laser passes through the multiple reflection pool 20, it passes through two polarization beam splitters 17 and is divided into three light signals. CH4 and H2S with relatively close wavelengths are detected by the same detector, and O2 and CO are detected by one detector each. Although this approach increases the complexity and cost of the system, it can significantly improve the accuracy and reliability of detection and meet the strict requirements of high-precision monitoring. By coupling four wavelengths of laser into one beam and matching it with a dedicated detector, the multi-component gas laser synchronous detection system improves the equipment integration and operation convenience, reduces the equipment size, and simplifies the installation and maintenance process.

[0036] The multi-component gas laser synchronous detection system of the present invention realizes the real-time monitoring of multiple gas components, and is particularly suitable for rapid response application scenarios such as chemical processing, environmental monitoring and safety assurance. At the same time, the environmental variables are monitored in real time through temperature and pressure sensors to ensure the accuracy and consistency of the measurement results, and enhance the reliability in the long-term monitoring process. Example 2

[0037] A multi-component gas laser synchronous detection method comprises the following steps: Step 1: After being driven by the CH4 and H2S analog voltage signals in the same direction and the O2 and CO analog voltage signals in the opposite direction, the CH4 laser 12, the H2S laser 15, the O2 laser 13, and the CO laser 14 respectively output four different wavelength detection lasers. The modulation signals corresponding to the four different wavelength detection lasers are as follows: Among them, U1, U2, U3 and U4 are the current modulation signals of CH4 laser 12, H2S laser 15, O2 laser 13 and CO laser 14 respectively; a1, a2, a3 and a4 are the bias currents corresponding to the four laser current modulation signals respectively; b1, b2, b3 and b4 are the modulation amplitudes of the four laser current modulation signals respectively.

[0038] Step 2: The four different wavelength detection lasers are coupled by the beam combiner 16 and output to the beam splitter 17, and are split into a measurement signal and a reference signal by the beam splitter 17; the reference signal is successively output to the signal processing module after passing through the multi-component sealed gas pool 18 and the wide-range photodetector 19, and the signal processing module demodulates to obtain the absorption peak position corresponding to the CH4, H2S, O2, and CO standard gas concentrations in the multi-component sealed gas pool 18 and outputs it to the laser driving module, so as to feedback and regulate the laser driving module to output four different modulation signals, and finally lock the central wavelength output by the corresponding laser module.

[0039] Step 3: The measurement signal after being absorbed by the gas to be measured in the multiple reflection pool 20 is: in, , , and They are the absorption signals of CH4, H2S, O2 and CO respectively.

[0040] Step 4: The measurement signals absorbed by the gas to be measured in the multiple reflection pool 20 are output to the polarization beam splitter prism 1 23 and the polarization beam splitter prism 2 22 in sequence, and are received by the photodetector 1 25, the photodetector 2 24 and the photodetector 3 21 respectively after being split by the polarization beam splitter prism 1 23 and the polarization beam splitter prism 2 22 and converted into photocurrent signals. The converted photocurrent signals I1, I2 and I3 are as follows: .

[0041] Step 5: The photocurrent signals are combined and output to the measurement signal processing module 11. The current signal I output after the combination is: .

[0042] Step 6: The measurement signal processing module 11 performs current isolation on the combined current signal in step 5 and converts it into a measurement voltage signal V: At this time, the modulation amplitudes b1, b2, b3 and b4 of the four laser current modulation signals cancel each other out.

[0043] From the above formula, we can see that when b1+b2=b3+b4, the voltage signal slope is 0, and the signal appears as a straight line with 4 gas absorption signals superimposed on it, such as Figure 3 of( a ) as shown in the figure.

[0044] When b1+b 2＞ When b3+b4, the voltage signal slope (b1+b2-b3-b4) is positive, and the slope is still much smaller than the single-channel modulation slopes b1, b2, b3, and b4. The signal appears as a monotonically increasing straight line with four gas absorption signals superimposed on it, such as Figure 3 of( b ) as shown in the figure.

[0045] When b1+b 2＜ When b3+b4, the voltage signal slope (b1+b2-b3-b4) is negative, and the slope is still much smaller than the single-channel modulation slope b1, b2, b3, b4. The signal appears as a monotonically decreasing straight line with four gas absorption signals superimposed on it, such as Figure 3 of( c ) as shown in the figure.

[0046] That is, after the four optical signals are superimposed, the modulation amplitudes b1+b2-b3-b4 of the four laser current modulation signals will cancel each other out. At this time, within the detectable voltage limit, the signal amplification factor can be greatly increased, thereby increasing the amplitude value and signal-to-noise ratio of each gas absorption signal, and ultimately achieving the purpose of improving the accuracy of gas synchronous detection. In addition, due to the use of synchronous laser modulation in the same direction and in the opposite direction, the absorption signal positions of the four gases can be set at the position of strong light intensity, so that the amplitude value and signal-to-noise ratio of the absorption signals of the four gases are significantly improved, thereby further improving the absorption detection accuracy of the four gases.

[0047] Step 7: The measured voltage signal V in step 6 is output to MCU1, and MCU1 calculates the CH4, H2S, O2 and CO gas concentration values ​​of the measured gas according to the Lambert-Beer gas absorption theorem.

[0048] Although the specification has been described in detail, it should be understood that various changes, substitutions and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims. In addition, the specific embodiments described are not intended to limit the scope of the invention, and those of ordinary skill in the art can easily understand based on the present invention that currently existing or later to be developed processes, machines, manufactures, material compositions, means, methods, or steps can perform substantially the same functions as the embodiments of the present invention or obtain substantially the same results. Therefore, the appended claims are intended to include such processes, machines, manufactures, material compositions, means, methods or steps within their scope.

Claims

1. A multi-component gas laser synchronous detection system, characterized in that: It includes a signal processing module, a laser driving module for outputting four different modulation signals, a laser module for outputting four different wavelength detection lasers, a beam combiner, a beam splitter, a multi-component sealed gas pool, a wide-range photodetector for detecting and responding to four wavelength spectrum ranges, a multiple reflection pool, a polarization beam splitter prism 1, a polarization beam splitter prism 2, a photodetector 1, a photodetector 2 and a photodetector 3; the laser driving module includes a co-directional amplifier circuit 1, a CH4 laser driving module, a co-directional amplifier circuit 2, an H2S laser driving module, a reverse amplifier circuit 1, an O2 laser driving module, a reverse amplifier circuit 2 and a CO laser driving module; The signal processing module outputs a digital-analog voltage signal, which is synchronously amplified in the same direction and reversely amplified by the same-direction amplifier 1, the same-direction amplifier 2 and the reverse amplifier 1, the reverse amplifier 2, and then respectively input into the corresponding CH4 laser driving module, the H2S laser driving module, the O2 laser driving module, and the CO laser driving module, and synchronously outputs the same-direction CH4 and H2S analog voltage signals and the reverse O2 and CO analog voltage signals to drive the corresponding CH4 laser, the H2S laser, the O2 laser, and the CO laser, and finally outputs four detection lasers with different wavelengths, which are coupled by the beam combiner and then output to the beam splitter, and are split into a measurement signal and a reference signal by the beam splitter; The reference signal is sequentially output to the signal processing module after passing through the multi-component sealed gas pool and the wide-band photoelectric detector. The signal processing module demodulates and obtains the absorption peak position corresponding to the CH4, H2S, O2, and CO standard gas concentrations in the multi-component sealed gas pool and outputs it to the laser driving module to feedback and control the laser driving module to output four different modulation signals, and finally lock the central wavelength output by the corresponding laser module; The measurement signal is absorbed by the gas to be measured in the multiple reflection pool and is output to polarization beam splitter prism 1 and polarization beam splitter prism 2 in sequence. After being split by polarization beam splitter prism 1 and polarization beam splitter prism 2, the measurement signal is received by photodetector 1, photodetector 2 and photodetector 3 respectively and converted into photocurrent signals. The photocurrent signals are combined and output to the signal processing module. The signal processing module calculates the CH4, H2S, O2 and CO gas concentration values ​​of the gas to be measured according to the multi-component gas laser synchronous detection method and Lambert-Beer gas absorption theorem.

2. A multi-component gas laser synchronous detection system as claimed in claim 1, characterized in that: The splitting ratio of the measurement signal to the reference signal is 9:

1.

3. A multi-component gas laser synchronous detection system as claimed in claim 1, characterized in that: The interior of the multi-component sealed gas pool is divided into four groups of independent small gas pools of equal width connected in series.

4. A multi-component gas laser synchronous detection system as claimed in claim 3, characterized in that: The four groups of independent small gas pools are respectively provided with CH4, H2S, O2, and CO gases of standard gas concentrations.

5. A multi-component gas laser synchronous detection system as claimed in claim 1, characterized in that: The signal processing module includes a reference signal processing module, an MCU, a measurement signal processing module and a DAC.

6. A multi-component gas laser synchronous detection system as claimed in claim 5, characterized in that: After the reference signal is absorbed by four groups of standard concentration gases in a multi-component sealed gas pool, the reference signal is converted into a photocurrent signal by a wide-area photodetector and then output to a reference signal processing module. The reference signal processing module converts the reference signal into a reference voltage signal and then outputs it to an MCU. The MCU demodulates to obtain the absorption peak positions corresponding to the four standard gas concentrations and outputs them to a DAC. The DAC converts the absorption peak position output into a digital-analog voltage signal to drive a laser driving module to lock the central wavelength output by the corresponding laser module.

7. A multi-component gas laser synchronous detection system as claimed in claim 6, characterized in that: The photocurrent signals are combined and output to the measurement signal processing module, and converted into measurement voltage signals by the measurement signal processing module and output to the MCU, which calculates the CH4, H2S, O2, and CO gas concentration values ​​of the gas to be measured.

8. A multi-component gas laser synchronous detection system as claimed in claim 1, characterized in that: The Lambert-Beer gas absorption theorem is as follows: in, I 0 is the incident light intensity, I t is the transmitted light intensity, α ( ν ) is the absorbance, k ν is the spectral absorption coefficient, S (T) is the temperature-dependent absorption line intensity, ϕ( ν ) is the normalized absorption line function, P is the pressure, X is the concentration of the gas, and L is the absorption path length, which is the optical path length in the multiple reflection cell.

9. A multi-component gas laser synchronous detection method, using a multi-component gas laser synchronous detection system as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: Step 1: After being driven by the same-direction CH4 and H2S analog voltage signals and the reverse-direction O2 and CO analog voltage signals, the CH4 laser, the H2S laser, the O2 laser, and the CO laser respectively output four different wavelength detection lasers. The modulation signals corresponding to the four different wavelength detection lasers are as follows: Among them, U1, U2, U3 and U4 are the current modulation signals of CH4 laser, H2S laser, O2 laser and CO laser respectively; a1, a2, a3 and a4 are the bias currents corresponding to the four laser current modulation signals respectively; b1, b2, b3 and b4 are the modulation amplitudes of the four laser current modulation signals respectively; Step 2: The four different wavelength detection lasers are coupled by a beam combiner and output to a beam splitter, and are split into a measurement signal and a reference signal by the beam splitter; the reference signal is sequentially output to a signal processing module after passing through a multi-component sealed gas pool and a wide-range photoelectric detector, and the signal processing module demodulates to obtain the absorption peak position corresponding to the CH4, H2S, O2, and CO standard gas concentrations in the multi-component sealed gas pool and outputs it to a laser driving module, so as to feedback and regulate the laser driving module to output four different modulation signals, and finally lock the central wavelength output by the corresponding laser module; Step 3: The measurement signal after being absorbed by the gas to be measured in the multiple reflection pool is: in, , , and They are the absorption signals of CH4, H2S, O2 and CO respectively; Step 4: The measurement signals absorbed by the gas to be measured in the multiple reflection pool are output to polarization beam splitter prism 1 and polarization beam splitter prism 2 in sequence, and are received by photodetector 1, photodetector 2 and photodetector 3 respectively after being split by polarization beam splitter prism 1 and polarization beam splitter prism 2 and converted into photocurrent signals. The converted photocurrent signals I1, I2 and I3 are as follows: Step 5: The photocurrent signals are combined and output to the measurement signal processing module. The current signal I output after the combination is: Step 6: The measurement signal processing module converts the combined current signal in step 5 into a measurement voltage signal V after current isolation: At this time, the modulation amplitudes b1, b2, b3 and b4 of the four laser current modulation signals cancel each other out; Step 7: The measured voltage signal V in step 6 is output to the MCU, which calculates the CH4, H2S, O2 and CO gas concentration values ​​of the measured gas according to the Lambert-Beer gas absorption theorem.

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