A gas detection device based on photoacoustic spectroscopy

Abstract

This invention relates to the field of gas detection technology, and more particularly to a gas detection device based on photoacoustic spectroscopy. The device comprises a laser emitting component, a first photoacoustic cell, an acoustic signal detection component, a signal amplification component, a phase detection component, and a visible light emitting component. The output end of the laser emitting component is aligned with the incident end of the first photoacoustic cell. The acoustic signal detection component is housed within the first photoacoustic cell, and its output end is connected to the input end of the signal amplification component. The output end of the signal amplification component is connected to the input end of the phase detection component. The output end of the phase detection component is connected to the laser emitting component. The visible light emitting component emits visible light towards the exit end of the first photoacoustic cell. The visible light passes through the first photoacoustic cell and propagates towards the laser emitting component, forming a calibration optical path. By adjusting the positions of the laser emitting component and the first photoacoustic cell according to the calibration optical path, the calibration of the detection optical path is achieved.

Description

Technical Field

[0001] This invention relates to the field of gas detection technology, and in particular to a gas detection device based on photoacoustic spectroscopy. Background Technology

[0002] Photoacoustic spectroscopy is a spectral analysis technique based on the photoacoustic effect. Since Bell discovered the photoacoustic effect in solids in 1880, it has a history of over a century. In recent years, with the maturation of semiconductor laser technology, gas detection based on photoacoustic spectroscopy has become a hot research area. It boasts advantages such as high detection sensitivity, fast response time, continuous real-time monitoring, small size, and the ability to detect multiple components of gases, making it widely used in petrochemical analysis, air pollution detection, coal mine gas concentration monitoring, dissolved gas analysis in transformer oil, and medical breath gas diagnosis. Photoacoustic spectroscopy measures the effect of absorbed light on matter through acoustic detection. Its working principle is as follows: the gas to be tested is dissolved in a background gas (e.g., air, nitrogen, or inert gas); the gas flows in a photoacoustic cell; when the wavelength of the gas to be tested corresponds to an absorption peak, a laser beam propagating in the photoacoustic cell immediately excites the background gas; the heat repeatedly generated from this absorption produces pressure fluctuations in the photoacoustic cell; these pressure fluctuations are detected by a microphone inside the photoacoustic cell; the gas to be tested is identified and its concentration is measured based on the wavelength of the laser and the recorded sound intensity.

[0003] Existing gas detection devices based on photoacoustic spectroscopy do not have optical path calibration components, and cannot calibrate the optical path offset caused by internal vibrations due to movement. The optical path offset will affect the detection results. Summary of the Invention

[0004] This invention provides a gas detection device based on photoacoustic spectroscopy, which solves the technical problem that existing gas detection devices based on photoacoustic spectroscopy cannot calibrate the optical path offset caused by internal vibration due to movement.

[0005] This invention provides a gas detection device based on photoacoustic spectroscopy, comprising:

[0006] The system comprises a laser emitting component, a first photoacoustic cell, an acoustic signal detection component, a signal amplification component, a phase detection component, and a visible light emitting component.

[0007] The output end of the laser emitting component is aligned with the incident end of the first photoacoustic cell;

[0008] The acoustic signal detection component is housed in the first photoacoustic cell, and its output terminal is connected to the input terminal of the signal amplification component.

[0009] The output of the signal amplification component is connected to the input of the phase detection component;

[0010] The output of the phase detection component is connected to the laser emission component;

[0011] The visible light emitting component is used to emit visible light to the emitting end of the first photoacoustic cell.

[0012] In a first possible implementation, the laser emitting assembly includes a laser and a function signal generator;

[0013] The output of the function signal generator is connected to the input of the laser;

[0014] The output end of the laser is aligned with the incident end of the first photoacoustic cell.

[0015] The second possible implementation also includes: a collimator;

[0016] One end of the collimator is aligned with the output end of the laser emitting assembly, and the other end is aligned with the incident end of the first photoacoustic cell.

[0017] The third possible device also includes: a second photoacoustic cell and a photoelectric detection component;

[0018] The second photoacoustic cell is used to contain the background gas;

[0019] The incident end of the second photoacoustic cell is aligned with the exit end of the first photoacoustic cell, and the exit end of the second photoacoustic cell is aligned with the input end of the photoelectric detection component.

[0020] The first photoacoustic cell is aligned with the input end of the photodetector.

[0021] In conjunction with the third possible implementation, the fourth possible implementation further includes: a waveform display component;

[0022] The input terminal of the waveform display component is connected to the output terminal of the photoelectric detection component;

[0023] The waveform display component is connected to the phase detection component via a signal connection.

[0024] In conjunction with the third possible device, in the fifth possible device, the visible light emitting component includes a visible light source and a beam splitter;

[0025] The first exit direction of the beam splitter corresponds to the incident end of the second photoacoustic cell, the second exit direction corresponds to the exit end of the first photoacoustic cell, and the incident direction corresponds to the output end of the visible light source.

[0026] In conjunction with the third possible device, in the sixth possible device, the visible light emitting component includes a visible light source, a beam splitter, and a reflector;

[0027] The first exit direction of the beam splitter corresponds to the incident end of the second photoacoustic cell, the second exit direction corresponds to the exit end of the first photoacoustic cell, and the incident direction corresponds to the reflection position of the mirror.

[0028] The output terminal of the visible light source corresponds to the reflection position.

[0029] In conjunction with the sixth possible device, in the seventh possible device, the reflector is a concave reflector.

[0030] In combination with any of the third to fourth possible implementations, in the eighth possible implementation, the photodetector component is a photodetector.

[0031] The waveform display component is an oscilloscope.

[0032] In combination with any of the above possible implementations, in the ninth possible implementation, the acoustic signal detection component is a capacitive microphone.

[0033] This signal amplification component is a preamplifier;

[0034] The phase detection component is a lock-in amplifier.

[0035] As can be seen from the above technical solutions, the present invention has the following advantages:

[0036] The gas detection device based on photoacoustic spectroscopy provided by this invention includes a laser emitting component, a first photoacoustic cell, an acoustic signal detection component, a signal amplification component, a phase detection component, and a visible light emitting component. The output end of the laser emitting component is aligned with the incident end of the first photoacoustic cell. The acoustic signal detection component is housed within the first photoacoustic cell, and its output end is connected to the input end of the signal amplification component. The output end of the signal amplification component is connected to the input end of the phase detection component. The output end of the phase detection component is connected to the laser emitting component. The visible light emitting component emits visible light towards the exit end of the first photoacoustic cell. By emitting visible light towards the exit end of the first photoacoustic cell using the visible light emitting component, the visible light passes through the first photoacoustic cell and propagates towards the laser emitting component, forming a calibration optical path that coincides with the standard detection optical path. By adjusting the positions of the laser emitting component and the first photoacoustic cell according to the calibration optical path, the calibration of the detection optical path can be achieved. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of a gas detection device based on photoacoustic spectroscopy, as shown in an embodiment of the present invention.

[0039] Among them: 1. Laser; 2. Collimator; 3. First photoacoustic cell.

[0040] 4. Beam splitter; 5. Second photoacoustic cell; 6. Photodetector

[0041] 7. Capacitor microphone 8. Preamplifier 9. Mirror

[0042] 10. Visible light source 11. Function signal generator 12. Lock-in amplifier

[0043] 13. Oscilloscope 14. Calibration optical path. Detailed Implementation

[0044] This invention provides a gas detection device based on photoacoustic spectroscopy, which solves the technical problem that existing gas detection devices based on photoacoustic spectroscopy cannot calibrate the optical path offset caused by internal vibrations due to movement.

[0045] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0046] In the description of the embodiments of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0047] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a replaceable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0048] Existing gas detection devices based on photoacoustic spectroscopy do not have optical path calibration components, and cannot calibrate the optical path offset caused by internal vibrations due to movement. The optical path offset will affect the detection results.

[0049] Please see Figure 1 The present invention provides a gas detection device based on photoacoustic spectroscopy, comprising:

[0050] The system comprises a laser emitting component, a first photoacoustic cell 3, an acoustic signal detection component, a signal amplification component, a phase detection component, and a visible light emitting component. The output end of the laser emitting component is aligned with the incident end of the first photoacoustic cell 3. The acoustic signal detection component is housed in the first photoacoustic cell 3, and its output end is connected to the input end of the signal amplification component. The output end of the signal amplification component is connected to the input end of the phase detection component. The output end of the phase detection component is connected to the laser emitting component. The visible light emitting component is used to emit visible light to the exit end of the first photoacoustic cell 3.

[0051] It should be noted that the laser emitting component is used to generate monochromatic lasers. Any device that can generate monochromatic lasers that meet the requirements can be used, such as Ar ion lasers, He-Ne lasers, CO2 lasers, semiconductor lasers, etc. In addition, in order to obtain modulated lasers, devices for amplitude modulation and frequency modulation of the lasers are also required, such as mechanical choppers, function signal generators, etc.

[0052] The first photoacoustic cell 3 is a closed container containing background gas, test gas, and acoustic signal detection components. A beam of monochromatic light with modulated intensity is used to irradiate the test gas sealed in the photoacoustic cell. The test gas absorbs the light energy and de-excites by releasing heat energy. The released heat energy causes the background gas and the test gas to be periodically heated according to the modulation frequency of the light, thereby causing periodic pressure fluctuations in the background gas and the test gas. This is the photoacoustic effect, and the concentration of the gas can be detected through the photoacoustic effect.

[0053] The acoustic signal detection component is used to detect pressure fluctuations in the photoacoustic cell and convert the pressure fluctuations into electrical signals. Any device that can detect pressure fluctuations can be used, such as microphones, piezoelectric ceramic microphones, etc.

[0054] The signal amplification component is used to amplify the electrical signal generated by the acoustic signal detection component due to pressure fluctuations. Any device that can amplify electrical signals can be used, such as an amplifier.

[0055] The phase detection component is used to separate the specific carrier frequency corresponding to the gas to be measured from the electrical signal amplified by the signal amplification component and amplify it again. That is, it is used to demodulate the electrical signal amplified by the amplification component into a photoacoustic signal related to the concentration of the gas to be measured. The concentration of the gas to be measured can be calculated based on the photoacoustic signal. Any device that can achieve the aforementioned function can be used, such as the lock-in amplifier 12.

[0056] The visible light generating component is used to generate a visible light beam. Any device that can stably generate a visible light beam can be used, such as a visible red light source 10 or a visible green light source. By shooting the visible light beam into the first photoacoustic cell 3 from the exit end and out from the incident end of the first photoacoustic cell 3, it propagates towards the laser emitting component and finally enters the laser emitting component from the output end of the laser emitting component, forming a calibration optical path 14 that coincides with the standard detection optical path. By adjusting the positions of the laser emitting component and the first photoacoustic cell 3 according to the calibration optical path 14, the offset of the detection optical path caused by the internal vibration caused by the movement of the gas detection device based on photoacoustic spectrum can be eliminated. The detection optical path is the propagation path of the laser used for gas detection, and the standard detection optical path is the laser propagation path before the offset occurs.

[0057] The output end of the laser emitting component is aligned with the incident end of the first photoacoustic cell 3 so that the modulated monochromatic laser generated by the laser emitting component can enter the first photoacoustic cell 3, allowing the gas to be tested in the first photoacoustic cell 3 to undergo a photoacoustic effect with the laser.

[0058] The acoustic signal detection component is housed in the first photoacoustic cell 3 to detect pressure fluctuations within the first photoacoustic cell 3. The output terminal of the acoustic signal detection component is connected to the input terminal of the signal amplification component to transmit the electrical signal converted from the pressure fluctuations to the signal amplification component, which then amplifies the electrical signal.

[0059] The output of the signal amplification component is connected to the input of the phase detection component to transmit the amplified electrical signal to the phase detection component. The phase detection component separates the specific carrier frequency corresponding to the gas under test from the amplified electrical signal and amplifies it again.

[0060] The output of the phase detection component is connected to the laser emission component to feed back the specific carrier frequency corresponding to the gas to be tested to the laser emission component. The laser emission component modulates the laser at this specific carrier frequency to form a detection optical path for gas detection, which can improve the detection accuracy.

[0061] The beneficial effects of this embodiment include:

[0062] ① By setting a visible light emitting component to emit visible light to the emitting end of the first photoacoustic cell 3, the visible light passes through the first photoacoustic cell 3 and propagates to the laser emitting component, forming a calibration optical path 14 that coincides with the standard detection optical path. By adjusting the positions of the laser emitting component and the first photoacoustic cell 3 according to the calibration optical path 14, the calibration of the detection optical path can be achieved.

[0063] ② By setting up a visible light emitting component to form a visible calibration optical path 14, the calibration of the detection optical path becomes more intuitive, facilitates the calibration of the detection optical path, and improves calibration efficiency.

[0064] Preferably, the laser emitting assembly includes a laser 1 and a function signal generator 11; the output terminal of the function signal generator 11 is connected to the input terminal of the laser 1; the output terminal of the laser 1 is aligned with the incident terminal of the first photoacoustic cell 3. The function signal generator 11 emits a voltage waveform signal of a certain frequency to provide a driving current for the laser 1. Driven by this driving current, the laser 1 generates an infrared laser of a specific frequency. The infrared laser is emitted from the output terminal of the laser 1 and propagates towards the first photoacoustic cell 3. It enters the first photoacoustic cell 3 from its input terminal and interacts with the gas to be measured to produce a photoacoustic effect.

[0065] Preferably, in order to maximize the coupling efficiency of the infrared laser into the first photoacoustic cell 3, a collimator 2 is also provided for the gas detection device based on photoacoustic spectrum; one end of the collimator 2 is aligned with the output end of the laser emitting component, and the other end is aligned with the incident end of the first photoacoustic cell 3. More specifically, the collimator 2 is located between the laser 1 and the first photoacoustic cell 3, with one end aligned with the output end of the laser 1 and the other end aligned with the incident end of the first photoacoustic cell 3. In this way, the infrared laser emitted by the laser 1 is collimated into the first photoacoustic cell 3 after passing through the collimator 2.

[0066] Preferably, the background gas in the first photoacoustic cell 3 has a slight absorption of infrared laser light, so the photoacoustic signal detected by the acoustic signal detection component includes noise caused by the background gas, reducing the detection signal-to-noise ratio. To eliminate this defect, a second photoacoustic cell 5 for containing the background gas and a photoelectric detection component for detecting the intensity of the laser light are provided for the gas detection device based on photoacoustic spectroscopy; the incident end of the second photoacoustic cell 5 is aligned with the emitting end of the first photoacoustic cell 3, and the emitting end of the second photoacoustic cell 5 is aligned with the input end of the photoelectric detection component, that is, the second photoacoustic cell 5 is located between the first photoacoustic cell 3 and the photoelectric detection component, as shown below. Therefore, after the infrared laser is emitted from the output end of the first photoacoustic cell 3, it propagates towards the second photoacoustic cell 5, enters the second photoacoustic cell 5 from the input end of the second photoacoustic cell 5, and then is emitted from the output end of the second photoacoustic cell 5, propagating towards the photodetector component, and entering the photodetector component from the input end of the photodetector component; or the output end of the first photoacoustic cell 3 is aligned with the input end of the photodetector component, that is, the second photoacoustic cell 5 is removed from between the first photoacoustic cell 3 and the photodetector component. In this way, after the infrared laser is emitted from the output end of the first photoacoustic cell 3, it propagates towards the photodetector component, and enters the photodetector component from the input end of the photodetector component. The infrared laser emitted by laser 1 passes sequentially through the first photoacoustic cell 3 and the second photoacoustic cell 5. The infrared laser is absorbed and attenuated by the gas to be tested in the first photoacoustic cell 3. At the same time, the background gas in the first photoacoustic cell 3 and the second photoacoustic cell 5 absorbs a small amount of the infrared laser. Thus, the concentration of the gas to be tested in the first photoacoustic cell 3 can be indirectly measured by photoacoustic spectroscopy, or the concentration of the gas to be tested in the first photoacoustic cell 3 can be directly measured by the infrared absorption method of the photoelectric detection component. The difference between the two measurement methods is that the photoacoustic spectroscopy method has higher measurement accuracy, while the infrared absorption method can detect the light intensity of the infrared laser by the photoelectric detection component. When the second photoacoustic cell 5 is placed between the first photoacoustic cell 3 and the photodetector, the photodetector detects the intensity of the infrared laser after passing through the first and second photoacoustic cells 3 and 5. The difference between this intensity and the initial intensity is used to calculate the absorbed intensity A1, where A1 represents the sum of infrared laser absorbed by the gas to be tested, the background gas in the first photoacoustic cell 3, and the background gas in the second photoacoustic cell 5. When the second photoacoustic cell 5 is removed from between the first photoacoustic cell 3 and the photodetector, the photodetector detects the intensity of the infrared laser after passing through the first photoacoustic cell 3. The difference between this intensity and the initial intensity is used to calculate the absorbed intensity A2, where A2 represents the sum of infrared laser absorbed by the gas to be tested and the background gas in the first photoacoustic cell 3. The absorbed intensity and the concentration of the gas to be tested follow Beer-Lambert's law. After a Taylor transformation of Beer-Lambert's law, the mathematical relationship is shown in the following formula. Substituting A1 into this formula calculates the corresponding concentration of the gas to be tested. Substitute A2 into the formula to calculate the corresponding concentration of the gas to be measured. and The difference is the error caused by the background gas in the second photoacoustic cell 5. This error is equal to the error caused by the background gas in the first photoacoustic cell 3. Therefore, by subtracting this error from the concentration of the gas to be measured calculated by photoacoustic spectroscopy, the noise caused by the background gas can be eliminated, thereby improving the signal-to-noise ratio.

[0067] formula:

[0068] in: Let a be the concentration of the gas to be measured. λ The absorption coefficient (fixed value) corresponding to the wavelength, where L is the optical path length and A is the optical path length. λ To absorb light intensity.

[0069] Preferably, in order to facilitate real-time observation of the intensity of the infrared laser, a waveform display component is also provided for the gas detection device based on photoacoustic spectroscopy; the input end of the waveform display component is connected to the output end of the photoelectric detection component, so that the intensity of the infrared laser detected by the photoelectric detection component can be transmitted to the waveform display component for real-time display; the waveform display component is signal-connected to the phase detection component, so that the photoacoustic signal of the concentration of the gas to be measured, modulated by the phase detection component, can also be wirelessly transmitted to the waveform display component for real-time display.

[0070] A preferred embodiment of the visible light emitting component: The visible light emitting component includes a visible light source and a beam splitter 4; the first emission direction of the beam splitter 4 corresponds to the incident end of the second photoacoustic cell 5, the second emission direction corresponds to the emission end of the first photoacoustic cell 3, and the incident direction corresponds to the output end of the visible light source. Thus, the visible light beam emitted by the visible light source is split into two visible light beams by the beam splitter 4. The propagation path of one beam is: the exit end of the first photoacoustic cell 3 > the entrance end of the first photoacoustic cell 3 > the collimator 2 > the output end of the laser 1. The propagation path of the other beam is: the entrance end of the second photoacoustic cell 5 > the exit end of the second photoacoustic cell 5 > the input end of the photodetector. The propagation paths of the two visible light beams are combined to form a calibration optical path 14 that coincides with the standard detection optical path. At this time, the propagation path of the infrared laser corresponding to the detection optical path is: the output end of the laser 1 > the collimator 2 > the entrance end of the first photoacoustic cell 3 > the exit end of the first photoacoustic cell 3 > the beam splitter 4 > the entrance end of the second photoacoustic cell 5 > the exit end of the second photoacoustic cell 5 > the input end of the photodetector.

[0071] To further optimize the calibration optical path 14 and make it more adjustable, a reflector is provided for the visible light emitting component. In this case, the first emission direction of the beam splitter 4 corresponds to the incident end of the second photoacoustic cell 5, the second emission direction corresponds to the emission end of the first photoacoustic cell 3, and the incident direction corresponds to the reflection position of the reflector; the output end of the visible light source corresponds to the reflection position. Thus, a visible light beam emitted from a visible light source is reflected by a reflector and then enters a beam splitter 4, which splits it into two visible beams. The propagation path of one beam is: exit end of the first photoacoustic cell 3 > entrance end of the first photoacoustic cell 3 > collimator 2 > output end of laser 1. The propagation path of the other beam is: entrance end of the second photoacoustic cell 5 > exit end of the second photoacoustic cell 5 > input end of the photodetector. The propagation paths of the two visible beams combine to form a calibration optical path 14 that coincides with the standard detection optical path. The propagation path of the infrared laser corresponding to the detection optical path is: output end of laser 1 > collimator 2 > entrance end of the first photoacoustic cell 3 > exit end of the first photoacoustic cell 3 > beam splitter 4 > entrance end of the second photoacoustic cell 5 > exit end of the second photoacoustic cell 5 > input end of the photodetector. The calibration optical path 14 can be adjusted by adjusting the positions of the reflector and beam splitter 4.

[0072] Preferably, the photoelectric detection component is a photoelectric detector 6; the waveform display component is an oscilloscope 13; the acoustic signal detection component is a capacitive microphone 7; the signal amplification component is a preamplifier 8; the phase detection component is a lock-in amplifier 12; the visible light source is a visible red light source 10; and the reflector is a concave reflector 9.

[0073] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A gas detection device based on photoacoustic spectroscopy, characterized in that, include: The system comprises a laser emitting component, a first photoacoustic cell, an acoustic signal detection component, a signal amplification component, a phase detection component, a visible light emitting component, a second photoacoustic cell, and a photoelectric detection component. The output end of the laser emitting component is aligned with the incident end of the first photoacoustic cell; The acoustic signal detection component is housed in the first photoacoustic cell, and its output terminal is connected to the input terminal of the signal amplification component. The output terminal of the signal amplification component is connected to the input terminal of the phase detection component; The output terminal of the phase detection component is connected to the laser emission component; The visible light emitting component is used to emit visible light towards the emitting end of the first photoacoustic cell; The second photoacoustic cell is used to contain the background gas; The incident end of the second photoacoustic cell is aligned with the emitting end of the first photoacoustic cell, and the emitting end of the second photoacoustic cell is aligned with the input end of the photoelectric detection component. Alternatively, the first photoacoustic cell may be aligned with the input end of the photoelectric detection component; The method for measuring gas concentration using the gas detection device includes the following steps: S1. The second photoacoustic cell is placed between the first photoacoustic cell and the photoelectric detection component. The photoelectric detection component detects the light intensity of the laser emitted by the laser emitting component after passing through the first photoacoustic cell and the second photoacoustic cell. The difference between the light intensity and the initial light intensity is used to calculate the absorbed light intensity A1. S2. Remove the second photoacoustic cell from between the first photoacoustic cell and the photoelectric detection component. Detect the intensity of the laser emitted by the laser emitting component after passing through the first photoacoustic cell using the photoelectric detection component. Calculate the absorbed light intensity A2 by subtracting the light intensity from the initial light intensity. S3. Substitute the absorbed light intensity A1 into the preset formula to calculate the corresponding concentration of the gas to be measured.

1. Substitute the absorbed light intensity A2 into a preset formula to calculate the corresponding concentration of the gas to be measured. 2; S4. The concentration of the gas to be measured 1 and the concentration of the gas to be measured 2. The error is obtained by subtracting the values ​​of the gas to be measured. Subtract the error from 1 to obtain the concentration of the gas to be measured.

2. The gas detection device based on photoacoustic spectroscopy according to claim 1, characterized in that: The laser emitting assembly includes a laser and a function signal generator; The output terminal of the function signal generator is connected to the input terminal of the laser; The output end of the laser is aligned with the incident end of the first photoacoustic cell.

3. The gas detection device based on photoacoustic spectroscopy according to claim 1, characterized in that, Also includes: Collimator; One end of the collimator is aligned with the output end of the laser emitting component, and the other end is aligned with the incident end of the first photoacoustic cell.

4. The gas detection device based on photoacoustic spectroscopy according to claim 1, characterized in that, Also includes: Waveform display component; The input terminal of the waveform display component is connected to the output terminal of the photoelectric detection component; The waveform display component is signal-connected to the phase detection component.

5. A gas detection device based on photoacoustic spectroscopy according to claim 1, characterized in that: The visible light emitting component includes a visible light source and a beam splitter; The first exit direction of the beam splitter corresponds to the incident end of the second photoacoustic cell, the second exit direction corresponds to the exit end of the first photoacoustic cell, and the incident direction corresponds to the output end of the visible light source.

6. The gas detection device based on photoacoustic spectroscopy according to claim 1, characterized in that: The visible light emitting component includes a visible light source, a beam splitter, and a reflector; The first exit direction of the beam splitter corresponds to the incident end of the second photoacoustic cell, the second exit direction corresponds to the exit end of the first photoacoustic cell, and the incident direction corresponds to the reflection position of the reflector. The output end of the visible light source corresponds to the reflection position.

7. The gas detection device based on photoacoustic spectroscopy according to claim 6, characterized in that: The reflector is a concave reflector.

8. A gas detection device based on photoacoustic spectroscopy according to any one of claims 4 to 7, characterized in that: The photoelectric detection component is a photoelectric detector; The waveform display component is an oscilloscope.

9. A gas detection device based on photoacoustic spectroscopy according to any one of claims 1 to 7, characterized in that: The acoustic signal detection component is a capacitive microphone; The signal amplification component is a preamplifier; The phase detection component is a lock-in amplifier.

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