Photoacoustic spectrometry gas detection self-correction method and system based on photoelectric detector

Abstract

The invention belongs to the technical field of gas detection, and discloses a photoacoustic spectrometry gas detection self-correction method and system based on a photoelectric detector, and the method comprises the following steps: substituting a sound pressure value of a to-be-detected gas and a light intensity value of a periodic light source into a mapping relation among the concentration, the sound pressure value and the light intensity value to obtain the concentration of the to-be-detected gas; wherein to-be-detected gas is introduced into the photoacoustic cell and generates a photoacoustic effect under the irradiation of the periodic light source; the sound pressure value is an electric signal converted from a sound pressure signal generated by the photoacoustic effect, and the light intensity value is detected by a photoelectric detector; the mapping relation construction method comprises the following steps: acquiring sound pressure values of standard gas with specific concentration and light intensity values of a periodic light source to obtain multiple groups of concentrations, sound pressure values and light intensity values; and fitting the mapping relationship among the plurality of groups of concentrations, sound pressure values and light intensity values to obtain the mapping relationship. Under the light source with variable light intensity, the accuracy and stability of gas concentration detection can be improved, and the detection mode is simple.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas detection, and more specifically, relates to a photoacoustic spectroscopy gas detection self-calibration method and system based on a photoelectric detector. Background Art

[0002] Thanks to the continuous advancements in various light sources, acoustic sensors, and other devices, photoacoustic spectroscopy has rapidly developed in the field of gas concentration detection. Photoacoustic spectroscopy gas detection can detect single- or multi-component gases, such as methanol, ethanol, ethylene, CO, N2O, and CO2. Photoacoustic spectroscopy gas detection is based on the photoacoustic effect. Light from a periodically modulated light source is incident on a photoacoustic cell filled with the gas to be detected. Excited by the periodically modulated light, the gas molecules undergo energy level transitions from the ground state to the excited state, releasing heat in the process. Due to the periodic modulation of the light, the gas molecules periodically expand and contract at the corresponding frequency, generating a periodically varying pressure wave, the acoustic signal. A microphone converts the acoustic pressure signal into an electrical signal, which is then inverted to obtain gas concentration information. The system architecture primarily comprises a light source, a light modulator, a photoacoustic cell, a microphone, and a signal processing module.

[0003] In theory, photoacoustic spectroscopy gas detection can accurately measure gas concentrations. However, in practice, the voltage used to drive the light source can easily fluctuate with external factors, making it difficult to precisely control the light source. This can lead to inaccurate gas concentration outputs. Consequently, various calibration techniques for photoacoustic spectroscopy gas detection have been proposed.

[0004] The patent application with publication number CN209821055U discloses an anti-interference photoacoustic spectroscopy gas detection device, which improves accuracy and anti-interference ability by adding a reference gas, but in the actual gas detection process, additional reference gas and its sealed gas chamber are required. The patent application with publication number CN104316466A discloses a photoacoustic spectroscopy gas detection device that can correct the resonant frequency of a quartz tuning fork in real time. It uses the idea of ​​harmonic detection and peak detection to measure the resonant frequency of the tuning fork and correct the frequency of the driving source signal to improve the stability of the system, but it requires real-time monitoring of the resonant frequency of the tuning fork. The patent application with publication number CN219016067U discloses a feedback photoacoustic spectroscopy gas detection device, which improves detection accuracy by setting a feedback loop to feedback-adjust the frequency and light wave, but it requires setting a feedback adjustment loop. Patent application number CN115615930B discloses a dual-stage absorption-enhanced photoacoustic spectroscopy gas detection method and device. This method monitors environmental factors in real time during detection and, when disturbances occur, promptly adjusts to the disturbance to ensure photoacoustic signal stability and gas detection accuracy. However, this method requires additional monitoring of environmental influences on the gas. Patent application number CN118225698A discloses a full-range laser photoacoustic spectroscopy gas detection device and method. This method uses the output first harmonic signal to monitor and calibrate the laser in real time, while the second harmonic signal is used to detect gas concentration. This method offers high detection sensitivity, but requires two harmonic signals, resulting in a high computational load. Patent application number CN115266600A discloses a FP cavity photoacoustic spectroscopy gas detection device. This method uses a proportional-integral-differential controller to modulate the input voltage signal of the detection laser based on electrical signal feedback to tune the detection laser's wavelength, thereby improving the sensitivity of photoacoustic spectroscopy gas detection. However, this method requires the use of two photoacoustic cells with identical structures, and a reference gas is required for actual detection. Patent application publication number CN114659985A discloses a photoacoustic spectroscopy gas detection method and system that integrates calibration and measurement. The method uses dual photoacoustic cells, one of which passes a standard gas for sensor coefficient calibration, and the other passes the gas to be measured for detection. The calibrated sensor coefficient is used to calculate the gas concentration, improving gas measurement accuracy. However, dual photoacoustic cells are required, and reference gas is needed in actual detection.

[0005] In summary, in order to improve the detection accuracy and the anti-interference ability of the system, the existing technology generally needs to add additional gas devices, requires reference gas in actual detection, needs to calibrate the light source or optical path, or needs to monitor the environment, etc., resulting in a high system complexity and certain inconveniences. In addition, the above-mentioned existing technologies do not consider the impact of changes in the light intensity of the light source on the accuracy of gas detection. In fact, due to the influence of interference such as the environment, the light intensity output by the light source will change, which will lead to inaccurate gas concentrations directly inverted based on the relationship between sound pressure and concentration. For example, when the light source is unstable, different gas concentrations will be obtained for the same gas under different light intensities. Summary of the Invention

[0006] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a self-calibration method and system for photoacoustic spectroscopy gas detection based on a photoelectric detector, the purpose of which is to improve the accuracy and stability of gas concentration detection under a light source with varying light intensity, and to simplify the detection method.

[0007] To achieve the above objectives, the present invention provides a self-calibration method for photoacoustic spectroscopy gas detection based on a photoelectric detector, comprising:

[0008] Substituting the sound pressure value of the gas to be measured and the light intensity value of the periodic light source into the mapping relationship between concentration, sound pressure value, and light intensity value to obtain the concentration of the gas to be measured; wherein the gas to be measured is passed into the photoacoustic cell and produces a photoacoustic effect under the illumination of the periodic light source; the sound pressure value is an electrical signal converted from the sound pressure signal generated by the photoacoustic effect; and the light intensity value is detected by a photodetector;

[0009] The mapping relationship between the concentration, sound pressure value and light intensity value is constructed by the following method:

[0010] Acquiring the sound pressure value of a standard gas of a specific concentration and the light intensity value of a periodic light source to obtain a set of concentration, sound pressure, and light intensity values; changing the concentration of the standard gas and repeating this step to obtain multiple sets of concentration, sound pressure, and light intensity values; wherein the standard gas is introduced into the photoacoustic cell and produces a photoacoustic effect under the illumination of the periodic light source, and the standard gas is of the same type as the gas to be measured;

[0011] The mapping relationships among the multiple groups of concentrations, sound pressure values, and light intensity values ​​are fitted to obtain the mapping relationships among the concentrations, sound pressure values, and light intensity values.

[0012] Furthermore, the photodetector is arranged on the light-emitting side of the periodic light source.

[0013] Furthermore, linear regression is used to fit the mapping relationships among multiple groups of concentrations, sound pressure values, and light intensity values ​​to obtain the mapping relationships among the concentrations, sound pressure values, and light intensity values.

[0014] Furthermore, a microphone is used to collect the sound pressure signal generated by the photoacoustic effect, and the sound pressure signal is converted into a corresponding electrical signal to obtain the sound pressure value.

[0015] Furthermore, the periodic light source includes a light source and a light source modulator;

[0016] The light source modulator is used to periodically modulate the light emitted by the light source.

[0017] The present invention also provides a photoacoustic spectroscopy gas detection self-calibration system based on a photoelectric detector, comprising a computer-readable storage medium and a processor;

[0018] The computer-readable storage medium is used to store executable instructions;

[0019] The processor is configured to read the executable instructions stored in the computer-readable storage medium to execute any one of the above-mentioned photoacoustic spectroscopy gas detection self-calibration methods based on a photoelectric detector.

[0020] The present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the self-calibration method for photoacoustic spectroscopy gas detection based on a photoelectric detector as described in any one of the above.

[0021] The present invention also provides a computer program product, comprising a computer program, which, when executed on a computer, enables the computer to execute any of the above-mentioned methods for self-calibration of gas detection by photoacoustic spectroscopy based on a photoelectric detector.

[0022] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0023] (1) The method of the present invention, by introducing the light intensity variable, pre-establishes the mapping relationship between the concentration, sound pressure value and light intensity value of the standard gas of known concentration. In the actual detection stage, it is only necessary to collect the sound pressure value and light intensity value of the gas to be measured to obtain the accurate concentration of the gas to be measured. Since the light intensity variable is introduced into the constructed mapping relationship, the mapping relationship can reflect the influence of the light intensity change of the light source on the concentration measurement of the gas to be measured. Therefore, the present invention is suitable for occasions where the light intensity of the light source is unstable. When the light intensity of the light source changes slightly, the accurate concentration of the gas to be measured can still be obtained according to the pre-established mapping relationship. In addition, the method of the present invention does not require light source calibration, light path calibration, additional gas devices, environmental monitoring, or changes to the original photoacoustic spectroscopy gas detection system. It only requires the addition of a low-cost photodetector for PD feedback to obtain accurate gas concentration, and the detection method is simple. Compared with the inaccurate gas concentration obtained by directly inverting the corresponding relationship between sound pressure and concentration when the light source is unstable, the method of the present invention can achieve self-correction of concentration, and the detection result is not affected by small changes in the light intensity of the light source, thereby improving the stability of gas detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of a self-calibration method for photoacoustic spectroscopy gas detection based on a photoelectric detector in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0026] Example 1

[0027] like Figure 1 As shown, an embodiment of the present invention provides a self-calibration method for photoacoustic spectroscopy gas detection based on a photoelectric detector, which mainly includes: an initial stage and an actual detection stage; wherein the initial stage includes steps S1-S2; the actual detection stage includes step S3.

[0028] S1. The standard gas of a specific concentration introduced into the photoacoustic cell produces a photoacoustic effect under the irradiation of a periodic light source, and obtains a sound pressure signal, wherein the type of the standard gas is the same as the type of the gas to be measured; the sound pressure signal is collected and converted into the corresponding sound pressure value (electrical signal), that is, Figure 1 The standard gas sound pressure value B in the image is obtained; at the same time, a photoelectric detector is used to collect the light intensity value of the current periodic light source ( Figure 1The PD detection value A in the image is used to obtain a set of data corresponding to the concentration, sound pressure value and light intensity value. The photodetector is set on the light-emitting side of the periodic light source.

[0029] S2, changing the concentration of the standard gas introduced into the photoacoustic cell, repeating step S2, obtaining multiple sets of data corresponding to concentration, sound pressure value and light intensity value; fitting the mapping relationship between concentration, sound pressure value and light intensity value based on multiple sets of data, that is, Figure 1 In the embodiment of the present invention, linear regression or the like is used to fit the mapping relationship among the concentration, the sound pressure value, and the light intensity value. In other embodiments, other data fitting methods may also be used.

[0030] S3. During the actual detection stage, the gas to be measured introduced into the photoacoustic cell produces a photoacoustic effect under the irradiation of a periodic light source, obtaining a sound pressure signal; the sound pressure signal is collected and converted into a corresponding sound pressure value; at the same time, a photoelectric detector is used to collect the light intensity value of the current periodic light source, and the current sound pressure value and light intensity value are substituted into the mapping relationship between concentration, sound pressure value and light intensity value to obtain the concentration of the gas to be measured.

[0031] In the embodiment of the present invention, a microphone is used to collect the sound pressure signal and convert it into a corresponding sound pressure value (electrical signal).

[0032] Example 2

[0033] The embodiment of the present invention provides a photoacoustic spectroscopy gas detection self-calibration system based on a photoelectric detector, comprising: a periodic light source, a photoacoustic cell, a microphone, a photoelectric detector and a signal processing module.

[0034] The periodic light source includes: a light source and a light source modulator; the light source modulator is used to modulate the light emitted by the light source to generate periodic light.

[0035] The photoacoustic cell is used to introduce a standard gas of a specific concentration in the initial stage and to introduce the gas to be tested in the actual detection stage; wherein, the standard gas of a specific concentration and the gas to be tested respectively produce a photoacoustic effect under the irradiation of a periodic light source, and obtain a corresponding sound pressure signal.

[0036] The microphone is used to collect the sound pressure signals of standard gases and test gases of different specific concentrations and convert them into corresponding electrical signals (sound pressure values).

[0037] The photodetector is installed on the light-emitting side of the light source and is used to collect the light intensity value of the periodic light source.

[0038] The signal processing module is used to fit the mapping relationship between concentration, sound pressure and light intensity values ​​based on the data corresponding to the concentration, sound pressure and light intensity values ​​of multiple sets of standard gases in the initial stage; in the actual detection stage, the sound pressure and light intensity values ​​of the gas to be measured are substituted into the mapping relationship between concentration, sound pressure and light intensity values ​​to obtain the concentration of the gas to be measured.

[0039] Information can be transmitted not only by circuits, but also by optical paths or wireless methods (such as Bluetooth, WIFI).

[0040] Example 3

[0041] An embodiment of the present invention provides a photoacoustic spectroscopy gas detection self-calibration system based on a photoelectric detector, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, the steps of the photoacoustic spectroscopy gas detection self-calibration method based on a photoelectric detector in the above-mentioned embodiment 1 are implemented.

[0042] The relevant technical solutions are the same as above and will not be repeated here.

[0043] Example 4

[0044] An embodiment of the present invention provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the steps of the self-calibration method for photoacoustic spectroscopy gas detection based on a photoelectric detector in the above-mentioned embodiment 1 are implemented.

[0045] Specifically, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage device.

[0046] The relevant technical solutions are the same as above and will not be repeated here.

[0047] Example 5

[0048] An embodiment of the present invention provides a computer program product, including a computer program. When the computer program is run on a computer, the computer executes the steps of the self-calibration method for photoacoustic spectroscopy gas detection based on a photoelectric detector in the above embodiment 1.

[0049] The relevant technical solutions are the same as above and will not be repeated here.

[0050] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A self-calibration method for photoacoustic spectroscopy gas detection based on a photoelectric detector, characterized in that: include: Substituting the sound pressure value of the gas to be measured and the light intensity value of the periodic light source into the mapping relationship between concentration, sound pressure value, and light intensity value to obtain the concentration of the gas to be measured; wherein the gas to be measured is passed into the photoacoustic cell and produces a photoacoustic effect under the illumination of the periodic light source; the sound pressure value is an electrical signal converted from the sound pressure signal generated by the photoacoustic effect; and the light intensity value is detected by a photodetector; The mapping relationship between the concentration, sound pressure value and light intensity value is constructed by the following method: Acquiring the sound pressure value of a standard gas of a specific concentration and the light intensity value of a periodic light source to obtain a set of concentration, sound pressure, and light intensity values; changing the concentration of the standard gas and repeating this step to obtain multiple sets of concentration, sound pressure, and light intensity values; wherein the standard gas is introduced into the photoacoustic cell and produces a photoacoustic effect under the illumination of the periodic light source, and the standard gas is of the same type as the gas to be measured; The mapping relationships among the multiple groups of concentrations, sound pressure values, and light intensity values ​​are fitted to obtain the mapping relationships among the concentrations, sound pressure values, and light intensity values.

2. The self-calibration method for photoacoustic spectroscopy gas detection based on a photoelectric detector according to claim 1 is characterized in that: The photodetector is disposed on the light emitting side of the periodic light source.

3. The self-calibration method for photoacoustic spectroscopy gas detection based on a photoelectric detector according to claim 2, characterized in that: Linear regression is used to fit the mapping relationships among multiple groups of concentrations, sound pressure values, and light intensity values ​​to obtain the mapping relationships among the concentrations, sound pressure values, and light intensity values.

4. The self-calibration method for photoacoustic spectroscopy gas detection based on a photoelectric detector according to claim 1, characterized in that: A microphone is used to collect the sound pressure signal generated by the photoacoustic effect, and the sound pressure signal is converted into a corresponding electrical signal to obtain the sound pressure value.

5. The self-calibration method for photoacoustic spectroscopy gas detection based on a photoelectric detector according to any one of claims 1 to 4, characterized in that: The periodic light source includes a light source and a light source modulator; wherein the light source modulator is used to periodically modulate the light emitted by the light source.

6. A self-calibration system for photoacoustic spectroscopy gas detection based on a photoelectric detector, characterized in that: comprising a computer-readable storage medium and a processor; The computer-readable storage medium is used to store executable instructions; The processor is configured to read the executable instructions stored in the computer-readable storage medium to execute the photoacoustic spectroscopy gas detection self-calibration method based on a photoelectric detector according to any one of claims 1 to 5.

7. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the self-calibration method for photoacoustic spectroscopy gas detection based on a photoelectric detector according to any one of claims 1 to 5 is implemented.

8. A computer program product, characterized in that The invention comprises a computer program, which, when running on a computer, enables the computer to execute the self-calibration method for photoacoustic spectroscopy gas detection based on a photoelectric detector according to any one of claims 1 to 5.

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