A multi-component gas concentration detection system

Abstract

The application discloses a multi-component gas concentration detection system, and relates to the field of gas concentration detection.The system comprises a light source for emitting detection light covering the target gas absorption waveband; a light splitting component for dispersing the detection light and forming at least a first light beam and a second light beam; a gas chamber provided with a light signal detection module and an acoustic signal detection module; and a first light modulator for wavelength selection and modulation of the second light beam; wherein the first light beam is received by the light signal detection module to form an absorption spectrum detection light path; and the second light beam is absorbed by the gas to be detected, excites an acoustic wave signal through a photoacoustic effect, and is received by the acoustic signal detection module to form a photoacoustic spectrum detection light path. The above scheme can simultaneously detect multi-component gases, has a compact detection structure, and has high sensitivity in detecting low-concentration gases.

Description

Technical Field

[0001] This invention relates to the field of gas concentration detection technology, and in particular to a multi-component gas concentration detection system. Background Technology

[0002] In semiconductor manufacturing processes, vapor deposition processes such as chemical vapor deposition (CVD), metal-organic chemical vapor deposition (MOCVD), and atomic layer deposition (ALD) all require precise monitoring of reactant and byproduct gases to ensure process stability and yield. Therefore, gas detection equipment is widely used in semiconductor process chambers, piping, and environmental monitoring to perform real-time detection and concentration monitoring of multi-component gases. In these applications, the detection equipment not only needs high sensitivity but also requires fast response speed and system stability to meet the high demands of complex process environments.

[0003] Currently, a wide variety of concentration detection devices are available on the market, employing different sensing technologies such as acoustic, optical, and mass spectrometry. Among existing gas detection technologies, non-dispersive infrared (NDIR) schemes are widely used due to their simple structure and mature technology. However, in multi-gas detection scenarios, traditional NDIR typically relies on fixed filters combined with mechanical filter wheels to distinguish the absorption bands of different gases. This approach has two significant problems: first, the filter wheel structure is bulky and requires a rotation drive mechanism, which not only increases the device size and power consumption but also leads to a significant reduction in response speed (switching time is typically on the order of hundreds of milliseconds); second, there is overlap between infrared absorption bands, for example... and Absorption in the infrared band is prone to cross-interference, which leads to a decrease in detection accuracy. Complex calibration algorithms are required for compensation, which further increases the system complexity and maintenance costs.

[0004] Therefore, while traditional NDIR schemes are suitable for routine detection of single gases, they are difficult to simultaneously detect multiple gases, have a compact structure, and achieve high sensitivity to low-concentration gases in real-time detection of multiple gases required for semiconductor processes, which has become a technical problem that urgently needs to be solved. Summary of the Invention

[0005] The purpose of this invention is to provide a multi-component gas concentration detection system to solve the technical problems in the prior art that make it difficult to simultaneously detect multiple gases, achieve a compact structure, and provide high sensitivity for detecting low-concentration gases.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A multi-component gas concentration detection system, comprising:

[0008] A light source, used to emit detection light covering the absorption band of the target gas;

[0009] A beam-splitting component is used to disperse the detection light and at least split it into a first beam and a second beam.

[0010] A gas chamber is used to contain the gas to be tested. The gas chamber is equipped with a light signal detection module and a sound signal detection module. The gas chamber has multiple optical windows.

[0011] A first optical modulator is used to select and modulate the wavelength of the second beam;

[0012] The processing unit is used to synchronously receive and process the light intensity signal output by the light signal detection module and the sound pressure signal output by the sound signal detection module;

[0013] The first light beam enters the gas chamber through one of the optical windows, penetrates the gas chamber, and is received by the optical signal detection module, forming an absorption spectral detection optical path; the modulated second light beam enters the gas chamber through another optical window, is absorbed by the gas to be tested, and excites an acoustic signal through the photoacoustic effect, which is received by the acoustic signal detection module, forming a photoacoustic spectral detection optical path.

[0014] Furthermore, the beam splitting component includes a second optical modulator and a beam splitter sequentially disposed on the optical path. The second optical modulator is used to spatially disperse the detection light according to wavelength, and the beam splitter is used to split the detection light into the first beam and the second beam.

[0015] Furthermore, both the first optical modulator and the second optical modulator include a micromirror array and a control unit. The micromirror array includes multiple micromirror units whose deflection angles can be changed independently. Changing the tilt direction of the micromirror unit can adjust the exit direction of the incident light after reflection. The control unit can drive and adjust the tilt direction of the multiple micromirror units.

[0016] Furthermore, the micromirror unit includes: a micromirror, a pivot hinged to the micromirror, and a control circuit unit for driving the micromirror to swing about the pivot.

[0017] Furthermore, the air chamber includes:

[0018] The housing is equipped with an air inlet and an air outlet;

[0019] A first optical window is located on one side of the housing, and a collimating lens is provided on the first optical window;

[0020] The second optical window is located on the other side of the housing and is equipped with a converging lens. The second optical window is positioned opposite to the optical signal detection module.

[0021] The third optical window is located on the housing and is equipped with a converging lens. The acoustic signal detection module is fixed inside the air chamber and is positioned opposite to the third optical window.

[0022] Furthermore, the optical signal detection module includes a photodetector and a photoelectric signal conditioning circuit electrically connected to the photodetector. The photodetector is used to receive the first light beam after it has been transmitted through the gas cell and convert it into an optical intensity electrical signal. The photoelectric signal conditioning circuit is used to amplify and filter the optical intensity electrical signal.

[0023] Furthermore, the acoustic signal detection module includes a microphone and an acoustic signal conditioning circuit electrically connected to the microphone. The microphone is used to detect the acoustic wave signal generated by the photoacoustic effect and convert it into an acoustic piezoelectric signal. The acoustic signal conditioning circuit is used to amplify and filter the acoustic piezoelectric signal.

[0024] Furthermore, the processing unit includes a signal demodulation module, a concentration inversion module, and a data fusion module; the signal demodulation module is used to perform frequency division multiplexing demodulation on the sound pressure signal to distinguish signals generated by different gas components; the concentration inversion module uses machine learning algorithms to process the light intensity signal and the demodulated sound pressure signal to decouple gas cross-interference and calculate the concentration of each gas component; the data fusion module is used to fuse and calibrate the calculation results of the absorption spectrum and photoacoustic spectrum, and output the final concentration value.

[0025] Furthermore, it also includes an environmental parameter sensing module, which is used to detect the temperature, humidity and pressure data in the air chamber in real time and transmit the data to the processing unit for concentration compensation.

[0026] Furthermore, the beam splitter is a 50:50 beam splitter, used to split the dispersed detection light into a first beam and a second beam with equal intensity.

[0027] The beneficial effects of the multi-component gas concentration detection system provided by this invention are as follows: Through a dual-channel optical path fusion design, absorption spectroscopy detection and photoacoustic spectroscopy detection work collaboratively within the same gas chamber, achieving a complementary combination of wide dynamic range and high sensitivity. This avoids the problems of large size and slow response caused by traditional NDIR relying on filters and mechanical switching, resulting in a more compact structure, reduced size and power consumption, and guaranteed response speed. Specifically, an optical signal detection module and an acoustic signal detection module are set in the same gas chamber. The two beams are incident through different optical windows, realizing dual-principle detection based on spectral absorption and photoacoustic effects. This reduces optical alignment errors and gas path switching losses caused by multi-chamber designs, resulting in higher detection efficiency. Furthermore, by wavelength selection and modulation of the second beam, replacing traditional mechanical filter wheels and fixed filters, rapid and flexible band selection is achieved, not only improving the selectivity of multi-component detection but also significantly enhancing the system's response speed. The optical signal detection module enables wide dynamic range detection, while the acoustic signal detection module provides high sensitivity response to low-concentration components, forming a complementary relationship. The processing unit simultaneously receives and fuses the two types of signals, which facilitates analysis, reduces error interference, and improves data accuracy. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the optical path of a multi-component gas concentration detection system according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the air chamber structure according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the overall structure of a multi-component gas concentration detection system according to an embodiment of the present invention;

[0031] Figure 4 This is a flowchart of a multi-component gas concentration detection method based on composite signals according to the present invention;

[0032] Figure 5 This is a flowchart of gas concentration analysis according to an embodiment of the present invention.

[0033] Reference numerals: 1. Light source; 2. Gas chamber; 21. Optical signal detection module; 22. Acoustic signal detection module; 221. Microphone; 23. First optical window; 24. Second optical window; 25. Third optical window; 3. First optical modulator; 4. Processing unit; 5. Second optical modulation component; 6. Beam splitter. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects.

[0035] The following is in conjunction with the appendix Figure 1 - Appendix Figure 5 The specific embodiments of the present invention will be further described in detail below.

[0036] Reference Figures 1-3 In some embodiments of the present invention, a multi-component gas concentration detection system includes a light source 1, a beam splitter, a gas chamber 2, a first light modulator 3, an optical signal detection module 21, an acoustic signal detection module 22, and a processing unit 4.

[0037] In some embodiments of the present invention, the light source 1 is used to emit broadband detection light covering the absorption band of the target gas; in some preferred embodiments, the light source 1 is preferably a broadband infrared light source, such as a MEMS blackbody radiation source or a quantum cascade laser, capable of covering the characteristic absorption band of the target gas, that is, covering the key absorption range of 2–12 μm. A beam splitter is used to disperse the detection light and at least split it into a first beam and a second beam; the gas chamber 2 is used to contain the gas to be measured, and is internally equipped with an optical signal detection module 21 and an acoustic signal detection module 22, with multiple optical windows on the outer wall of the gas chamber 2; a first optical modulator 3 is used to perform wavelength selection and modulation on the second beam;

[0038] In some specific embodiments of the present invention, the first optical modulator 3 preferably employs a digital micromirror device, which can select a specific wavelength of modulated light to enter the gas chamber 2 according to a control signal to excite the photoacoustic effect. The processing unit 4 is used to synchronously receive and process the light intensity signal output by the optical signal detection module 21 and the sound pressure signal output by the acoustic signal detection module 22. Specifically, the first light beam enters the gas chamber 2 through an optical window, passes through the gas chamber 2, and is received by the optical signal detection module 21, forming an absorption spectral detection optical path based on Beer-Lambert's law; the modulated second light beam enters the gas chamber 2 through another optical window, is absorbed by the gas molecules to be measured, and excites an acoustic signal, which is then received by the acoustic signal detection module 22, forming a photoacoustic spectral detection optical path based on the photoacoustic spectral effect. This design integrates photoacoustic spectroscopy and spectral absorption technology in the same system, fully utilizing the advantages of high sensitivity of photoacoustic signals and their immunity to optical scattering and detector drift, as well as the advantages of wide dynamic range and ease of calibration of spectral absorption technology, thereby achieving efficient and accurate multi-component gas detection.

[0039] In some specific embodiments of the present invention, the beam splitting component includes a second optical modulator and a beam splitter 6 arranged sequentially on the optical path. The second optical modulator preferably employs a digital micromirror device for wavelength dispersion and spatial distribution control of the broadband detection light. The second optical modulator can act as a grating to disperse the broadband light source 1. The beam splitter 6 is preferably a 50:50 beam splitter, used to divide the dispersed detection light into two paths of equal intensity, which serve as the inputs to the absorption detection path and the photoacoustic detection path, respectively. Through the high-speed encoding control of the digital micromirror device and the beam distribution of the beam splitter 6, the system can achieve simultaneous detection of multiple components of gas without the need for multiple independent light sources 1. Compared with traditional methods relying on multiple light sources 1 or laser tuning, this scheme has a more compact structure, reduces system cost, and avoids the problems of large size and slow response caused by mechanical filter wheels.

[0040] Furthermore, both the first optical modulator 3 and the second optical modulator include a micromirror array and corresponding control components. The micromirror array consists of multiple micromirror units whose deflection angles can be independently changed. Each micromirror unit includes a rotatable micromirror, a pivot connected to it, and a circuit unit for driving the micromirror to swing around the pivot. The control components change the outgoing light path by adjusting the tilt direction of each unit. Through this structure, the second optical modulator can perform dynamic band selection and dispersion of the broadband light source 1, and the first optical modulator 3 can rapidly modulate the beam of the incident gas chamber 2, realizing frequency division multiplexing control. In this way, the absorption and photoacoustic optical paths not only share the same broadband light source 1, but also can achieve independent control of different target gas bands through programming, replacing traditional filter combinations or laser arrays, significantly improving the system detection efficiency. This invention can monitor 1-8 gases (e.g., ...) almost simultaneously. (or CO), if there are more than 8, the number of sensors at the signal receiving end of the spectral absorption section needs to be increased. The other parts are applicable in principle, only the number of sensors and the overall volume need to be changed.

[0041] In some specific embodiments of the present invention, the air chamber 2 includes a housing with an air inlet and an air outlet. The inner wall of the air chamber 2 is gold-plated to reduce light scattering. The resonant cavity formed by the air chamber 2 adopts a Helmholtz structure to suppress external noise. The optimized structure of the air chamber 2 is beneficial to improving the photoacoustic conversion efficiency. The first optical window 23 is located on one side of the housing and is equipped with a collimating lens to ensure that the incident light enters collimatedly. The second optical window 24 is located on the other side of the housing and is equipped with a converging lens to focus the transmitted light onto the optical signal detection module 21. The third optical window 25 is located on the top of the housing and is also equipped with a converging lens to effectively guide the modulated light into the air chamber 2 and make it opposite to the acoustic signal detection module 22. An acoustic resonant cavity structure can be further formed inside the air chamber 2. The acoustic signal detection module 22 is preferably a high-sensitivity microphone 221 with a frequency response of 20Hz–20kHz, installed in the area with the strongest acoustic field intensity. Through the shared design of the optical and gas paths described above, the system can simultaneously perform spectral absorption detection and photoacoustic detection in the same gas chamber 2, avoiding optical alignment errors and gas path switching losses caused by the multi-chamber 2 design, and greatly improving detection efficiency.

[0042] Reference Figure 1 The specific optical path connections are shown below, where arrows represent the light emission directions: The detection light emitted by the light source 1 first enters the second optical modulator, which includes a micromirror array and its control components. Through coding control of the micromirror units, a portion of the beam is selectively diffracted according to a preset wavelength and reflected to the beam splitter 6 (i.e., BS). After being split by the beam splitter 6, the detection light is divided into two paths, one part of which is transmitted to form an absorption spectral detection optical path, and the other part is reflected to form a photoacoustic spectral detection optical path. After the transmitted light enters the absorption spectral detection optical path through the beam splitter 6, it sequentially enters the gas chamber 2 through the first optical window 23, penetrates the gas sample, and exits through the second optical window 24, finally being received by the optical signal detection module 21 to achieve absorption spectral detection. Another portion of the light reflected by the beam splitter 6 enters the first optical modulator 3. The first optical modulator 3 selectively reflects the light beam of the target wavelength into the gas chamber 2 through the programming control of its micro-mirror array. The light then enters the interior of the gas chamber 2 through the third optical window 25, and uses the photoacoustic effect to excite the acoustic wave signal, which is then collected by the acoustic signal detection module 22, thus forming the photoacoustic spectral detection optical path.

[0043] The upper limit of the detection range for the concentration of multi-component gases mainly depends on the micromirror array. It is also necessary to consider whether the gases being detected have spectral overlap and whether there is interference in the spectral bands of the light source. In some specific embodiments of this invention, the reaction gases in current semiconductor processes mainly consist of two categories: metal-organic sources (MO sources) and hydrides. Hydrides are typically present in high-pressure cylinders and must be diluted to a safe concentration with a high-purity carrier gas or other high-purity reaction gases before use. Metal-organic sources are precursors of elements such as Ga, In, Al, Group II (Zn, Mg, Cd), or Group IV (Sn, Ge). They are usually compounds formed by combining the metal with organic groups (such as methyl, ethyl). These are precisely controlled and delivered to the reaction chamber, where they undergo thermal decomposition and chemical reactions on the heated substrate surface, depositing the desired semiconductor material. Therefore, it is necessary to detect the concentration of these multi-component gases to ensure accurate delivery of the aforementioned process reaction gases. Furthermore, the gaseous byproducts generated after the reaction undergo thermal decomposition and chemical reactions between the MO source and hydrides within the reaction chamber. While depositing the target semiconductor thin film on the substrate, a large amount of volatile byproduct gases are also produced. The main byproducts are hydrocarbons and hydrogen, depending on the organic groups in the MO source used. Most of these byproducts are highly toxic and need to be detected, rapidly removed by the vacuum system, and treated. Therefore, both semiconductor process reaction gases and volatile byproduct gases require high-precision multi-component gas concentration detection.

[0044] It is important to note that absorption spectroscopy detection, based on the intensity changes of broadband transmitted light, can simultaneously acquire the absorption characteristics of multiple gas components in a single measurement, thereby retrieving the concentrations of various gases in parallel, resulting in high detection efficiency. In contrast, photoacoustic spectroscopy relies on modulating specific wavelengths of light to excite the acoustic response of corresponding gas molecules. Therefore, in multi-component detection, the target wavelength band needs to be switched sequentially via the first optical modulator 3 to perform time-division detection of different gases. Thus, absorption spectroscopy is suitable for rapid parallel measurement of multiple components, while photoacoustic spectroscopy provides high sensitivity compensation for low-concentration components; combining the two can balance detection efficiency and sensitivity.

[0045] In some specific embodiments of the present invention, the optical signal detection module 21 includes a photodetector and an optoelectronic signal conditioning circuit electrically connected thereto. The photodetector can be flexibly selected according to requirements, such as a multi-channel pyroelectric sensor, a multi-channel thermopile sensor, or a charge-coupled device spectrometer. The optoelectronic signal conditioning circuit amplifies and filters the received light intensity signal to ensure stable and reliable output data. Compared with traditional solutions relying on a single fixed filter, the optical path and detector interface design provided by the present invention expands the selection range of detection devices, enabling flexible configurations of high resolution, multi-channel, or low cost according to specific application requirements.

[0046] In some specific embodiments of the present invention, the acoustic signal detection module 22 includes a microphone 221 and an electrically connected acoustic signal conditioning circuit. The microphone 221 is used to detect the acoustic wave signal generated by the photoacoustic effect and convert it into an electrical signal; the acoustic signal conditioning circuit amplifies and filters the electrical signal. By combining lock-in amplification or digital demodulation methods, environmental noise can be effectively suppressed, and the detection sensitivity for trace gases can be improved. Compared with the spectral absorption channel, the photoacoustic channel does not depend on the absolute value of light intensity, but directly reflects the gas absorption characteristics through acoustic response, thus providing higher detection accuracy in low-concentration scenarios.

[0047] In some specific embodiments of the present invention, in terms of data processing, the processing unit 4 includes a signal demodulation module, a concentration inversion module, and a data fusion module. The signal demodulation module is responsible for frequency division multiplexing demodulation of the acoustic signal to distinguish the acoustic responses of different gas components; the concentration inversion module uses machine learning algorithms to model and calculate the light intensity signal and the demodulated sound pressure signal, decouple cross-interference, and invert the concentration of each gas; the data fusion module fuses and calibrates the two types of detection results, photoacoustic and spectral absorption, preferably using a Kalman filter algorithm for dynamic weighting, enhancing the weight of the photoacoustic signal in the low concentration range and enhancing the weight of the absorption signal in the high concentration range, thereby achieving high-precision detection across the entire range. Through this signal collaborative processing method, the high sensitivity of photoacoustic and the wide dynamic range of absorption are complementary, further reducing error interference. In some other embodiments of the present invention, the processing unit 4 can also control the on / off state of the light source 1 and its on / off power.

[0048] In some other embodiments of the present invention, the system further includes an environmental parameter sensing module for real-time acquisition of temperature, humidity, and pressure data within the air chamber 2, and transmission of this data to the processing unit 4 for compensation calculation. This design can correct for the effects of environmental changes on the optical absorption cross-section and sound velocity, improving detection reliability in complex application scenarios.

[0049] In some embodiments of the present invention, the processing unit 4 is electrically connected to a screen. The processing unit is capable of processing and analyzing light and sound signals, and the processed and calculated data is displayed on the screen for easy recording and viewing by the operator.

[0050] The multi-component gas concentration detection system proposed in this invention organically combines a single broadband light source 1, a beam splitter, a first optical modulator 3, and a second optical modulator, taking advantage of both photoacoustic spectroscopy and spectral absorption principles. Structurally, it not only avoids the problems of large size, high cost, and slow response associated with multiple light sources 1 and mechanical filter wheels, but also significantly reduces system cost and detection time, while improving detection efficiency and flexibility through deep integration of optical path, gas path, and signal processing.

[0051] Reference Figure 4 and Figure 5 In some other embodiments of the present invention, a method for detecting the concentration of multi-component gases based on composite signals is provided. This method is applicable to gas concentration detection systems employing a single broadband light source 1 and combining photoacoustic spectroscopy and spectral absorption detection principles. It enables high-sensitivity and wide dynamic range detection of multi-component gases within the same gas chamber 2, and includes the following steps:

[0052] Specifically, the method includes the following steps: First, the detection light emitted from the broadband light source 1 is modulated using a digital micromirror device. Through programming control of the micromirror array in the digital micromirror device, the detection light is selectively reflected according to a preset wavelength sequence, thereby forming a controllable beam that is incident on the gas chamber 2. The gas chamber 2 contains two independent optical paths: an absorption spectroscopy detection path and a photoacoustic spectroscopy detection path. These two paths share the light source 1 and the gas path within the same gas chamber 2, but do not interfere with each other. The absorption spectroscopy detection path receives the transmitted light after penetrating the gas sample through a photodetector and outputs a first signal; the photoacoustic spectroscopy detection path excites the photoacoustic effect of gas molecules by modulating the beam, and the acoustic signal is collected by a microphone 221 and outputs a second signal. The system achieves synchronous acquisition of the first and second signals.

[0053] Subsequently, the first signal is processed to obtain a first concentration value C1 calculated based on the principle of spectral absorption; the second signal is processed to obtain a second concentration value C2 calculated based on the principle of photoacoustic spectroscopy. Since the two types of signals have complementary characteristics, the system introduces a dynamic selection mechanism based on preset rules during concentration inversion. Specifically: If C1 and C2 are both within a first preset concentration range (in some embodiments of the present invention, the first preset concentration range is 12 ppm to 990 ppm), then C1 is output as the target gas concentration value to take advantage of the stability and good linearity of the absorption spectrum in the medium concentration range; if C1 and C2 are both within a second preset concentration range (in some embodiments of the present invention, the second preset concentration range is below 7 ppm or above 1010 ppm), then C2 is output to take advantage of the high sensitivity and anti-saturation characteristics of photoacoustic spectroscopy under trace and high concentration conditions; if C1 and C2 are within different preset ranges, then it is further determined whether they are within a critical range (in some embodiments of the present invention, the critical range is 7–12 ppm or 990–1010 ppm), and the output result is selected or a fusion algorithm is used for processing based on the difference between the two.

[0054] In the fusion process, this invention proposes a recursive filtering method based on uncertainty measurement. First, state prediction is performed, using the concentration estimate from the previous moment and the uncertainty measurement to obtain the predicted value for the current moment. Then, two types of signals are sequentially introduced for updating: first, C1 is incorporated into the predicted value, and intermediate estimates and uncertainties are calculated; then, this is used as a new prior estimate to introduce C2, completing the final update and obtaining the target concentration value. The weights of different signals are determined by their respective uncertainty parameters, which are obtained through calibration experiments in a stable gas environment and are proportional to the statistical variance of the signal. Thus, in the medium concentration range, if the variance of the absorbed signal is small, its weight in the fusion is greater; conversely, the photoacoustic signal has a greater weight, achieving signal reliability-driven adaptive fusion.

[0055] Specifically, in some other embodiments of the present invention, selecting to output C1, C2, or the value after data fusion of C1 and C2 based on the numerical difference between C1 and C2 includes:

[0056] Calculate the absolute value of the difference between C1 and C2, |C1-C2|; if |C1-C2| is greater than a preset difference threshold, output the smaller of C1 and C2 as the target gas concentration value; if |C1-C2| is less than or equal to the preset difference threshold, use a data fusion algorithm to fuse C1 and C2, and use the fusion result as the target gas concentration value.

[0057] In some other embodiments of the present invention, the preset difference threshold is 1 ppm.

[0058] In some other embodiments of the present invention, the data fusion employs a recursive filtering algorithm based on uncertainty metrics, specifically a Kalman filtering algorithm, the steps of which include:

[0059] S1: State Prediction

[0060]

[0061]

[0062] in Let k be the predicted gas concentration value at time k. This represents the optimal estimate of the gas concentration at time k-1. Let be the measure of prediction uncertainty at time k, which is also the current best estimate covariance. Q is the estimation uncertainty measure at time k-1, where Q is the known process noise covariance and is a pre-set confidence parameter close to zero.

[0063] S2: Sequential Update:

[0064] S21: First, update using the first concentration value C1:

[0065]

[0066]

[0067]

[0068] in, The first fusion weight at time k and with C1 concentration. This is the preset reliability parameter corresponding to the first concentration value C1. This is an intermediate estimate after incorporating C1. for , This is the corresponding intermediate uncertainty measure;

[0069] S22: Subsequently, and As a new prior estimate, the second concentration value C2 is used for updating:

[0070]

[0071]

[0072] in, For time k, and with C2 concentration as the second fusion weight, This is the preset reliability parameter corresponding to the second concentration value C2. This refers to the target gas concentration value after data fusion at time k. The updated uncertainty metric is used for calculation in the next time step.

[0073] In some other embodiments of the present invention, the preset confidence parameter and The measurement data of the absorption spectroscopy detection optical path and the photoacoustic spectroscopy detection optical path were recorded over a period of time after calibration in a stable gas environment, and their statistical variances were calculated. and The value assigned is proportional to the statistical variance.

[0074] In some other embodiments of the present invention, when the statistical variance of the absorption spectroscopy detection optical path in the intermediate concentration range is less than that of the photoacoustic spectroscopy detection optical path, i.e. < During the sequential update process, the first fusion weight Always greater than the second fusion weight ;

[0075] When the statistical variance of the absorption spectroscopy detection optical path in the intermediate concentration range is greater than that of the photoacoustic spectroscopy detection optical path, that is... < During the sequential update process, the first fusion weight Always less than the second fusion weight .

[0076] Implementation example assumptions:

[0077] Q = 1e-5, assuming the process noise is very small;

[0078] = 1.0, assuming low variance of noise in the spectral absorption channel;

[0079] = 4.0, assuming the photoacoustic channel noise variance is high and more unstable;

[0080] = 0.1, representing the uncertainty estimated at the previous moment;

[0081] = 100.0 ppm, which is the best estimate at the previous time step;

[0082] S1: State Prediction

[0083]

[0084]

[0085] S2 is updated sequentially, starting with S21: updated with the spectral absorbance value C1 = 101.5 ppm.

[0086]

[0087]

[0088]

[0089] At this point, the weight of C1 is approximately 0.09.

[0090] S22: Update with photoacoustic value C2 = 104.0 ppm

[0091]

[0092]

[0093]

[0094] At this point, the weight of C2 is only 0.022.

[0095] Therefore, the final output concentration is: ppm

[0096] In this example, because the preset noise R1 of the spectral absorption channel C1 is smaller, the system automatically assigns it a higher weight (0.09 vs 0.022) during fusion. The final result is closer to the value of C1 than a simple average of the two. This process is performed automatically in each filtering cycle, achieving adaptive weighted fusion.

[0097] In some other embodiments of the present invention, the method further includes structured storage supporting the result data. The system can store the real-time acquired first concentration value C1, second concentration value C2, and fused target concentration value. and the corresponding measurement timestamps and uncertainty measurement parameters. Fusion weight parameters and The data is stored in non-volatile memory, thus providing a foundation for subsequent data tracing and trend analysis.

[0098] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the present invention. Furthermore, the present invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A multi-component gas concentration detection system, characterized in that, include: Light source (1) is used to emit detection light covering the absorption band of the target gas; A beam-splitting component is used to disperse the detection light and at least split it into a first beam and a second beam. The gas chamber (2) is used to contain the gas to be tested. The gas chamber (2) is equipped with a light signal detection module (21) and a sound signal detection module (22). The gas chamber (2) has multiple optical windows. The first optical modulator (3) is used to select and modulate the wavelength of the second beam; The processing unit (4) is used to synchronously receive and process the light intensity signal output by the light signal detection module (21) and the sound pressure signal output by the sound signal detection module (22); The first beam enters the gas chamber (2) through one of the optical windows, penetrates the gas chamber (2) and is received by the optical signal detection module (21), forming an absorption spectrum detection optical path; the modulated second beam enters the gas chamber (2) through another optical window, is absorbed by the gas to be tested and then excites a sound wave signal through photoacoustic effect, which is received by the sound signal detection module (22), forming a photoacoustic spectrum detection optical path. The beam splitting component includes a second optical modulator and a beam splitter (6) arranged sequentially on the optical path. The second optical modulator is used to spatially disperse the detection light according to wavelength, and the beam splitter (6) is used to split the detection light into the first beam and the second beam.

2. The multi-component gas concentration detection system according to claim 1, characterized in that, Both the first optical modulator (3) and the second optical modulator include a micromirror array and a control unit. The micromirror array includes multiple micromirror units whose deflection angle can be changed independently. The change of the tilt direction of the micromirror unit can adjust the outgoing direction of the incident light after reflection. The control unit can drive and adjust the tilt direction of the multiple micromirror units.

3. The multi-component gas concentration detection system according to claim 2, characterized in that, The micromirror unit includes: a micromirror, a pivot hinged to the micromirror, and a control circuit unit for driving the micromirror to swing about the pivot.

4. The multi-component gas concentration detection system according to claim 3, characterized in that, The air chamber (2) includes: The housing is equipped with an air inlet and an air outlet; A first optical window (23) is provided on one side of the housing, and a collimating lens is provided on the first optical window (23); The second optical window (24) is located on the other side of the housing and is equipped with a converging lens. The second optical window (24) is positioned opposite to the optical signal detection module (21). The third optical window (25) is located on the housing and is equipped with a converging lens. The acoustic signal detection module (22) is fixed inside the air chamber (2) and is positioned opposite to the third optical window (25).

5. The multi-component gas concentration detection system according to claim 4, characterized in that, The optical signal detection module (21) includes a photodetector and an optical signal conditioning circuit electrically connected to the photodetector. The photodetector is used to receive the first light beam after it is transmitted through the gas chamber (2) and convert it into an optical intensity electrical signal. The optical signal conditioning circuit is used to amplify and filter the optical intensity electrical signal.

6. The multi-component gas concentration detection system according to claim 1, characterized in that, The acoustic signal detection module (22) includes a microphone (221) and an acoustic signal conditioning circuit electrically connected to the microphone (221). The microphone (221) is used to detect the acoustic wave signal generated by the photoacoustic effect and convert it into an acoustic piezoelectric signal. The acoustic signal conditioning circuit is used to amplify and filter the acoustic piezoelectric signal.

7. The multi-component gas concentration detection system according to claim 1, characterized in that, The processing unit (4) includes a signal demodulation module, a concentration inversion module, and a data fusion module. The signal demodulation module is used to perform frequency division multiplexing demodulation on the sound pressure signal to distinguish the signals generated by different gas components. The concentration inversion module uses a machine learning algorithm to process the light intensity signal and the demodulated sound pressure signal to decouple gas cross-interference and calculate the concentration of each gas component. The data fusion module is used to fuse and calibrate the calculation results of the absorption spectrum and the photoacoustic spectrum, and output the final concentration value.

8. The multi-component gas concentration detection system according to claim 1, characterized in that, It also includes an environmental parameter sensing module, which is used to detect the temperature, humidity and pressure data in the gas chamber (2) in real time and transmit the data to the processing unit (4) for concentration compensation.

9. A multi-component gas concentration detection system according to claim 1, characterized in that, The beam splitter (6) is a 50:50 beam splitter, used to split the dispersed detection light into a first beam and a second beam with equal intensity.

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