Particle analysis method and device based on particle size spectrum, storage medium and electronic equipment

Abstract

The invention relates to a particle analysis method and device based on a particle size spectrum, a storage medium and electronic equipment, and the device comprises a light beam generation shaping unit, a light source monitoring unit, a stray light filtering unit, an isolation unit, a sample chamber, an APD, a PMT and an operation unit, after light splitting, laser beams output to the light source monitoring unit for detection and laser beams output to the stray light filtering unit are obtained; the stray light filtering unit forms parallel light beams at equal intervals, and the parallel light beams are output into the sample chamber through the isolation unit; the sample chamber inputs a lateral diffuse reflection light beam to the APD for detection and inputs a forward diffuse reflection light beam to the PMT for detection when a detected sample falls to a light focus; the operation unit receives detection information of the light source monitoring unit, the APD and the PMT and performs coherent operation; and determining information for particle analysis according to the signal-to-noise ratio of the information after the coherent operation. The analysis efficiency can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of kinetic particle size analysis, and in particular to a particle analysis method, device, storage medium and electronic equipment based on particle size spectrum. Background Art

[0002] The kinetic particle size spectrometer (particle size spectrometer) is a device based on fluid dynamics and polarization optics for statistical analysis of different kinetic particle sizes. It can analyze the particle size and concentration of particles of different sizes in the sample to be tested in real time. It is widely used in environmental monitoring, pharmaceutical production and research and development, gas particle analysis, liquid particle detection, advanced manufacturing, dust-free analysis and other fields. The kinetic particle size spectrometer is used to detect the particle size and concentration of particles to judge the state of the sample to be tested. For example, in the field of environmental protection, the size and concentration of particles in the atmosphere (sample to be tested) are monitored by the kinetic particle size spectrometer to determine the degree of pollution; for pharmaceutical companies, the size and concentration of particles after atomization of the drug (sample to be tested) are determined to determine whether the drug is qualified; for high-end manufacturing fields such as semiconductors, the concentration and size of particles in the air (sample to be tested) in the workshop are measured to determine whether the cleanliness of the workshop is qualified.

[0003] The following is a brief introduction to the related kinetic particle size spectrometer for particle concentration measurement in the prior art.

[0004] The first is a particle size spectrum based on the filter membrane weighing method. It is placed in the test environment, and uses a filter membrane with multiple preset apertures as a filter net to measure the weight volume of particles remaining on the filter membrane for a certain period of time. Based on the aperture, the single particle volume of the particles corresponding to the aperture is obtained, and then the concentration of the particles is calculated based on the large particle volume and the measured weight volume. Its advantages are low cost; disadvantages are large errors and the need for manual intervention.

[0005] The second is the particle size spectrum based on the extinction method. The extinction method is a particle concentration measurement method based on the Lambert-Beer law. By measuring the absorption intensity of the light source by the particles, combined with filtering, the concentration of particles within a certain size range can be detected. Its advantage is automatic measurement; its disadvantage is that it is easily interfered.

[0006] The third type is the particle size spectrum based on light scattering, and the basic principle is Mie scattering theory. When light shines on particles, it will be absorbed and scattered. The intensity of the scattered light is related to the particle size, concentration, wavelength of the incident light and the scattering angle. Therefore, the concentration and particle size distribution of the particles can be calculated using the scattered light intensity. Its advantages are automatic measurement and high accuracy; its disadvantage is that it is easily interfered.

[0007] The fourth type is the particle size spectrum based on the β-ray absorption method. β-rays are absorbed when passing through particles. When the energy of the emitted rays is constant, the absorbed energy is proportional to the mass of the particles. In this way, the concentration of particles in a certain range of sizes can be detected by combining a filter membrane with a certain aperture. Its advantage is high measurement accuracy; its disadvantage is that the filter membrane needs to be replaced regularly and the timeliness is poor.

[0008] The fifth type is the particle size spectrum based on the oscillating balance method. Its core principle is the correspondence between the mass of the oscillating end and the oscillation frequency. When the mass of the oscillating end changes, its oscillation frequency also changes. The mass of the oscillating end is measured through this change. The gas to be tested is pumped into a replaceable filter membrane using a vacuum pump. The filter membrane is installed at the oscillating end. The mass concentration of the particulate matter is obtained by correction based on the flow rate of the gas to be tested, the temperature and pressure of the gas to be tested per unit time. Its advantages are high measurement accuracy and good real-time performance; its disadvantages are high maintenance frequency and susceptibility to interference.

[0009] The sixth type is the particle size spectrum based on the charge method. The measurement principle is that when particles flow near the probe, they will generate a certain amount of charge due to electrostatic induction. The amount of charge is proportional to the number of particles. By measuring the amount of charge, the concentration of particles can be obtained. Its advantages are high accuracy, high timeliness, stability and reliability; its disadvantages are that it is easily disturbed and can only measure charged particles.

[0010] There are mainly the following types of equipment for measuring particle size.

[0011] The first is a particle size spectrum based on the scanning electromigration method. The scanning electromigration technology is based on the measurement of the charge. The instrument uses a vacuum pump to suck the particles into the internal particle impactor, and the impactor causes the particles to generate charges. Generally, the larger the diameter of the particles, the more charge they have. The charged particles are drawn into a measurement area with a slit (generally composed of inner and outer concentric circles). The electric field is controlled by controlling the voltage on both sides of the slit. Different electric fields can be used to screen out particles of different sizes. Its advantages are fast measurement speed and high resolution; its disadvantages are that it cannot measure uncharged particles and cannot measure particles of 1μm and below.

[0012] The second is the particle size spectrum based on the laser diffraction scattering method. According to the Furanhofer diffraction and Mie scattering theory, when the incident light hits the particles, a diffraction effect will occur. The larger the particle size, the smaller the angle of scattered light, and the smaller the particle size, the larger the angle of scattered light. Therefore, the size of the particle can be measured according to the size of the diffraction spot. Its advantage is that the measurement result is not affected by factors such as temperature, medium viscosity, particle density and surface characteristics; its disadvantage is that the cost is high, the equipment is complex, and it is easily disturbed by vibration.

[0013] The third type is based on the aerodynamic particle size spectrum. Particles of different diameters have different speeds under a certain speed of gas jet. When particles of different speeds pass through a measurement area composed of parallel light with gaps, they will be illuminated by parallel light. The longer the time the particle flies through the parallel light, the wider the peak interval of the light scattering peak obtained by the detector. The aerodynamic diameter of the particle can be obtained through the time interval of the peak. Its advantages are high equipment reliability, high real-time performance and high precision; its disadvantage is that the measurement sensitivity of small particles is not enough.

[0014] As can be seen from the above, the aerodynamic-based particle size spectrometer has the characteristics of high reliability, high real-time performance and high precision. However, due to its designed optical structure, its recognition sensitivity for particles with a size below 1 um is low, and its measurement efficiency is low when used for particle size measurement, thus limiting its further application. Summary of the invention

[0015] In view of this, the present invention provides a particle analysis method, device, storage medium and electronic device based on particle size spectrum.

[0016] Specifically, the present invention is achieved through the following technical solutions: According to a first aspect of the present invention, a particle analysis device based on a particle size spectrum is provided, and the particle analysis device based on a particle size spectrum comprises: A beam forming and shaping unit, a light source monitoring unit, a stray light filtering unit, an isolation unit, a sample chamber, an avalanche photodiode detector, a photomultiplier tube detector and a computing unit, wherein: A beam generation and shaping unit is used to excite the first linear polarized light of the collimated light, adjust the polarization state of the first linear polarized light to the second linear polarized light with the same energy of the horizontal component and the vertical component, expand the second linear polarized light, and then split it according to a preset splitting ratio to obtain a first laser beam and a second laser beam, output the first laser beam to the light source monitoring unit, and converge the second laser beam to form a converged beam and output it to the stray light filtering unit, wherein the laser energy of the first laser beam is less than the laser energy of the second laser beam; A light source monitoring unit, used for detecting first light intensity information of the first laser beam, obtaining first voltage information after transformation, and outputting the first voltage information to the operation unit; A stray light filtering unit is used to split the converged light beam to form two parallel light beams along the X axis with equal spacing on the Y axis at the focus of the light in the sample chamber, filter out the stray light of the parallel light beam, and output the parallel light beam with the stray light filtered out into the sample chamber through the isolation unit; The isolation unit includes a first window mirror and a second window mirror, wherein the first window mirror is connected to the aperture and is used to isolate the sample chamber from the beam generating and shaping unit, or the sample chamber from the stray light filtering unit, so as to prevent the gas to be detected with particles in the sample chamber from contaminating the optical path environment of the beam generating and shaping unit and the stray light filtering unit, and the second window mirror is used to isolate the sample chamber from the avalanche photodiode detector, and the sample chamber from the photomultiplier tube detector, respectively; The sample chamber is used to input the sample to be tested. When the sample to be tested falls to the focus of the two parallel light beams, it is irradiated by the two parallel light beams and diffusely reflects with the particles contained in the sample to be tested. After the lateral diffuse reflection light beams are converged, they are input to the avalanche photodiode detector. After the forward diffuse reflection light beams are converged, they are input to the photomultiplier tube detector. An avalanche photodiode detector is used to detect the second light intensity information of the lateral diffusely reflected light beam, obtain the second voltage information after transformation, and output it to the operation unit; A photomultiplier tube detector is used to detect the third light intensity information of the forward diffuse reflection light beam, obtain the third voltage information after transformation, and output it to the operation unit; A calculation unit is used to receive the first light intensity information, the second light intensity information and the third light intensity information, and to perform a coherent calculation on the first light intensity information and the second light intensity information according to a preset coherent algorithm to obtain effective information detected by the APD, and to perform a coherent calculation on the first light intensity information and the third light intensity information to obtain effective information detected by the PMT; According to the signal-to-noise ratio of the effective information detected by the APD, it is determined whether the effective information detected by the APD or the effective information detected by the PMT is used for particle analysis, wherein the particle analysis includes: particle concentration of particle size corresponding to the particle size distribution.

[0017] According to a second aspect of the present invention, a particle analysis method based on a particle size spectrum is provided, which is applied to the above-mentioned particle analysis device. The particle analysis method based on a particle size spectrum includes: Turn on the particle analysis device, introduce zero gas after self-checking, obtain the optimal APD coefficient based on the first light intensity information of the light source monitoring unit and the second light intensity information of the avalanche photodiode detector, and obtain the optimal PMT coefficient based on the first light intensity information of the light source monitoring unit and the third light intensity information of the photomultiplier tube detector; Passing sample gas, obtaining a first light scattering APD based on first light intensity information of the light source monitoring unit, second light intensity information of the avalanche photodiode detector and an optimal APD coefficient, and obtaining a second light scattering APD based on first light intensity information of the light source monitoring unit, third light intensity information of the photomultiplier tube detector and an optimal PMT coefficient; Based on a preset signal-to-noise ratio calculation formula, respectively calculating the signal-to-noise ratio of the first light-scattering APD and the signal-to-noise ratio of the second light-scattering APD; Based on the signal-to-noise ratio of the first light-scattering APD, the signal-to-noise ratio of the second light-scattering APD, and a preset signal-to-noise ratio threshold, a light-scattering APD for particle analysis is determined from the first light-scattering APD and the second light-scattering APD.

[0018] According to a third aspect of the present invention, there is provided a storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the particle analysis method based on particle size spectrum in any possible implementation of the first aspect.

[0019] According to a fourth aspect of the present invention, there is provided an electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the steps of the particle analysis method based on particle size spectrum in any possible implementation of the first aspect are implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or related technical descriptions are briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 A schematic diagram of the structure of a particle analysis device based on particle size spectrum provided by an embodiment of the present invention; Figure 2 A schematic diagram of an aperture structure provided in an embodiment of the present invention; Figure 3 A schematic diagram of the main structure of a sample chamber provided in an embodiment of the present invention; Figure 4 A schematic diagram of the side view structure of the sample chamber provided in an embodiment of the present invention; Figure 5 Another schematic diagram of the main structure of the sample chamber provided by the embodiment of the present invention; Figure 6 A schematic diagram of the structure of an aerodynamic gas nozzle provided by an embodiment of the present invention; Figure 7 A schematic diagram of calculating the Brewster angle provided by an embodiment of the present invention; Figure 8 A schematic diagram of the particle analysis principle provided by an embodiment of the present invention; Fig. 9 A schematic diagram of a process flow of a particle analysis method based on a particle size spectrum provided by an embodiment of the present invention; Fig.10 Another schematic diagram of a process of a particle analysis method based on particle size spectrum provided by an embodiment of the present invention; Fig.11 A schematic diagram of another process of a particle analysis method based on particle size spectrum provided by an embodiment of the present invention; Fig.12 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In the related technology, the sensitivity of the aerodynamic particle size spectrometer mainly depends on the following two points: first, the sensitivity of the photoelectric detector, whether it can detect the weak scattered light of tiny particles below the micron level. Since the aerodynamic particle size spectrometer uses a photoelectric avalanche diode (APD), which has a higher photocurrent gain inside, it has a higher gain than the photoelectric PD, but its gain still cannot reach the photon level detection, so the aerodynamic particle size spectrometer based on the APD photoelectric detector cannot achieve high-efficiency detection of particles below the micron level. Second, the signal-to-noise ratio of the entire optical system of the particle size spectrum, because large noise will drown out the light scattering signal of small particles, and the sample chamber-level light source of the aerodynamic particle size spectrometer uses an ordinary stray light extinction device, resulting in a large light background, which drowns out the scattered light of small particles and cannot detect tiny particles. That is, the current particle size spectrometer based on dynamics only installs an APD photoelectric detector on the side of the light beam. Under the action of a certain voltage, it can amplify the photoelectrons generated by the surface material, with a magnification of about 100 times, and is usually used for weak light detection and analysis. However, due to its limited gain and relatively high noise, it is still unable to detect the size and concentration of particles below 1um, and its detection sensitivity for small particles in the Rayleigh scattering range is insufficient. Therefore, it cannot be used in fields that require smaller particle sizes, making the measurement efficiency of the particle size spectrometer low.

[0025] According to the Mie scattering theory and Rayleigh scattering theory in light scattering, when particles of different speeds pass through a measurement area composed of parallel light with a fixed gap, a scattering effect will be generated on the parallel light. Among them, if the particle size and the wavelength of light are close, the Mie scattering effect will occur, and the forward scattered light energy is majority, followed by the side scattered light, and the backward scattered light is the least; when the particle size is much smaller than the wavelength of light, the Rayleigh scattering effect will occur, and the particle forward and backward scattered light energy is majority, and the side scattered light is the least; when the particle size is much larger than the wavelength of light, it tends to the scattering in geometric optics, and the forward scattered light is majority.

[0026] In this embodiment, based on the Mie scattering theory and Rayleigh scattering theory in light scattering, a particle size acquisition and analysis method based on an improved optical structure particle size spectrum is provided, which can solve the problem of low sensitivity in detecting particles below 1um in the particle size spectrometer based on kinetics in related technologies, and help to quickly distinguish the size and concentration of finer particles, thereby meeting high-end application scenarios of quickly measuring the particle size and concentration of smaller particles, effectively expanding the application field of the particle size spectrometer based on kinetics, while improving the accuracy and speed of particle size measurement, reducing the cost in the field of particle size measurement, and improving the measurement efficiency of the particle size spectrometer. Specifically, (1) The surface material of the PMT photomultiplier tube can generate photoelectrons by utilizing the photoelectric effect, and the multi-stage high-voltage circuit can multiply and amplify the photoelectrons. For example, a general 10-stage photomultiplier tube can internally achieve 1024 (2^10) times amplification, and due to its special structural characteristics, its noise is also low. If it is combined with a low-noise analog amplifier circuit, it can achieve a higher gain, making PMT widely used in photon-level signal detection, such as in the fields of medicine, nuclear energy, and space exploration. Therefore, in this embodiment, a particle size spectrometer based on two detectors, an avalanche photodiode (APD) and a photomultiplier tube (PMT), is used to detect the scattered light intensity and flight time of particles of different sizes, respectively. Among them, the APD with relatively low sensitivity is used to measure the scattered light intensity of particles above the micron level passing through the optical system of the particle size spectrometer, and the size and concentration of the corresponding particles are analyzed based on the measured scattered light intensity; the PMT with single-photon sensitivity is used to measure the scattered light intensity of particles below the micron level passing through the optical system, and then analyze their size and concentration. That is, in this embodiment, based on the Mie scattering principle and the Rayleigh scattering principle, a single-photon PMT detector for forward scattering is added to the aerodynamic particle size spectrometer to detect the forward scattered light of small particles below the micron level, so as to make up for the problem that the APD photoelectric sensor in the existing aerodynamic particle size spectrometer is not sensitive enough to the extremely weak side scattered light signal of small particles. In this embodiment, the PMT detector is installed at the end of the laser emission direction of the detection chamber.

[0027] (2) By designing a laser light source status monitoring function for the particle size spectrometer, the light source noise caused by changes in temperature and electromagnetic environment can be monitored in real time. In this way, the output results of the APD at the light source end used for the monitoring function and the output results of the APD and PMT at the particle measurement end can be correlated to reduce the system noise of the particle size spectrometer and improve the signal-to-noise ratio, thereby improving the measurement accuracy of particle size and concentration.

[0028] (3) For the polarization differential optical path of the (dynamic) particle size spectrometer, by designing the extinction structure of the sample chamber light inlet, the light contamination of the particle sample chamber by the diffracted light can be minimized, thereby reducing the background noise of the APD and PMT at the back end (particle measurement end), and effectively improving the signal-to-noise ratio.

[0029] (4) A high-efficiency extinction chamber is designed for the end of the optical path of the kinetic particle size spectrometer to reduce the amount of light reflected back to the detection chamber (optical chamber), thereby reducing the background noise of the APD and PMT and effectively improving the signal-to-noise ratio.

[0030] See also Figure 1 An embodiment of the present invention provides a particle analysis device based on particle size spectrum. In this embodiment, the particle analysis device based on particle size spectrum includes: a beam generating and shaping unit, a light source monitoring unit, a stray light filtering unit, an isolation unit, a sample chamber, an avalanche photodiode detector 11, a photomultiplier tube detector 12 and a computing unit, wherein the beam generating and shaping unit, the light source monitoring unit, the stray light filtering unit, the isolation unit, the sample chamber and the computing unit are not shown in the figure.

[0031] A beam generation and shaping unit is used to excite the first linear polarized light of the collimated light, adjust the polarization state of the first linear polarized light to the second linear polarized light with the same energy of the horizontal component and the vertical component, expand the second linear polarized light, and then split it according to a preset splitting ratio to obtain a first laser beam and a second laser beam, output the first laser beam to the light source monitoring unit, and converge the second laser beam to form a converged beam and output it to the stray light filtering unit, wherein the laser energy of the first laser beam is less than the laser energy of the second laser beam; In this embodiment, as an optional embodiment, the beam generating and shaping unit includes: a laser 001, a paddle 002, a first concave lens 003, a first convex lens 004, a beam splitter 005, a second convex lens 006, and a third convex lens 007, wherein: Laser 001, used for exciting and outputting the first linear polarized light of the collimated light; The paddle 002 is connected to the laser 001, vertically receives the first linear polarized light emitted by the laser 001, adjusts the polarization state of the incident first linear polarized light so that the energy of the horizontal component is the same as the energy of the vertical component, obtains the second linear polarized light and outputs it; In this embodiment, as an optional embodiment, the diameter of the first linear polarized light excited by the laser is 1 mm, and the plate is a 1 / 4 wave plate. The laser emitting collimated light outputs the first linear polarized light with a diameter of 1 mm, which is vertically incident on the 1 / 4 wave plate, and the angle of the 1 / 4 wave plate is adjusted by rotating to adjust the polarization state of the incident first linear polarized light to the second linear polarized light with the same horizontal component energy and vertical component energy.

[0032] The first concave lens 003 is connected to the paddle 002 and receives the second linearly polarized light output by the paddle 002; The first convex lens 004 is connected to the first concave lens 003. The first concave lens 003 and the first convex lens 004 form a beam expander for expanding the incident second polarized light to obtain expanded light; In this embodiment, as an optional embodiment, the first concave lens and the first convex lens are both circular. After the second linearly polarized light output by the 1 / 4 wave plate after adjusting the rotation angle passes through the beam expander composed of the circular concave lens and the circular convex lens, the diameter of the first linearly polarized light (the first polarized light of the thin light beam emitted by the laser) or the second linearly polarized light can be widened to 4-5mm. In this way, the beam expander composed of the first concave lens and the first convex lens can be used to filter out some stray light, improve the quality of the expanded light (laser beam) obtained after expanding the second linearly polarized light, and improve the accuracy of subsequent particle size and concentration statistics. As an optional embodiment, the diameter of the expanded light is 4-5mm.

[0033] The beam splitter 005 is connected to the first convex lens 004 and is used to split the expanded light to obtain a first laser beam reflected from the beam splitter 005 and a second laser beam penetrating the beam splitter. The first laser beam is incident on the second convex lens 006, and after being converged by the second convex lens 006, it is incident on the light source monitoring unit. The second laser beam is incident on the third convex lens 007. The laser energy of the first laser beam is much smaller than the laser energy of the second laser beam. In this embodiment, as an optional embodiment, the spectroscope is a calcite spectroscope.

[0034] The third convex lens 007 is connected to the beam splitter 005 and is used to converge the second laser beam in the Y-axis direction representing the vertical component energy to obtain a converged beam, which is incident on the stray light filtering unit, wherein the horizontal component energy and the vertical component energy of the polarization state of the converged beam are the same.

[0035] In this embodiment, the first laser beam is output to the light source monitoring unit through the second convex lens, and the second laser beam is output to the stray light filtering unit through the third convex lens.

[0036] In this embodiment, as an optional embodiment, the third convex lens is a cylindrical convex lens, and as an optional embodiment, the ratio of the laser energy of the first laser beam to the laser energy of the second laser beam is less than 1: 9. For example, after the beam expander passes through the beam splitter, 90% of the laser energy (the second laser beam) can be transferred to the next-level cylindrical convex lens to realize the convergence of the light of the second laser beam in the Y-axis direction after the beam expansion is split to the focus, thereby forming a 4-5 mm wide light plane along the X-axis at the focus.

[0037] In this embodiment, the horizontal component energy and the vertical component energy of the polarization state of the light rays converged in the Y-axis direction by the cylindrical convex lens are the same.

[0038] In this embodiment, a laser, a quarter wave plate, a calcite beam splitter, a beam expander consisting of a first concave lens and a first convex lens, and a cylindrical convex lens constitute a beam generation and shaping unit, wherein the laser is a linearly polarized light output unit in the beam generation and shaping unit; the quarter wave plate can adjust the polarization angle of the beam, so that the horizontal component energy of the first linearly polarized light is the same as the vertical component energy, and the second linearly polarized light is obtained. After the second linearly polarized light passes through the first concave lens, the first convex lens, and the beam splitter, a first laser beam and a second laser beam are formed. Among them, the beam expander and the cylindrical convex lens are mainly used for beam shaping, filtering stray light with a large divergence angle deviation, and improving the beam quality.

[0039] In the beam shaping unit, as an optional embodiment, the expanded light after beam expansion passes through a beam splitter to reflect 10% of the expanded light to the ADP, i.e., the light source monitoring unit, in a direction perpendicular to the original light beam (expanded light) to achieve real-time monitoring of the expanded light.

[0040] A light source monitoring unit, used for detecting first light intensity information of the first laser beam, obtaining first voltage information after transformation, and outputting the first voltage information to the operation unit; In this embodiment, as an optional embodiment, the light source monitoring unit includes a first avalanche photodiode 008 (light source end ADP). After the expanded light passes through the beam splitter, 10% of the expanded light (first laser beam) is reflected to the first ADP in a direction perpendicular to the original light beam (expanded light) to achieve real-time monitoring of the light source.

[0041] In this embodiment, the light source noise monitoring unit is used to monitor the light source, which can solve the problem of abnormal fluctuation of the light source.

[0042] In this embodiment, in the aerodynamic particle size spectrometer, the stability of the linear polarized light as the light source has a very large impact on the overall performance. The light source in the aerodynamic particle size spectrometer is a semiconductor laser, which is easily affected by temperature changes and electromagnetic radiation, resulting in light source jitter, which affects the detection of light scattering characteristics. For example, when the light source becomes weaker, the scattered light irradiated on the same particles will also weaken, and may be mistakenly identified as the scattered light of the particles, thereby affecting the operation of the aerodynamic particle size spectrometer. Secondly, as the working time of the laser in the aerodynamic particle size spectrometer increases, a certain degree of attenuation will occur, which will also lead to deviations in the analysis of the scattering characteristics of the particles; at the same time, the light emission of the semiconductor laser will also be affected by the electromagnetic environment, vibration, etc. For example, power supply noise, periodic electromagnetic radiation and strong vibration will cause the laser intensity output by the semiconductor laser to change instantaneously, and the instantaneous change will cause the recognition algorithm of the dynamic particle size spectrometer to misjudge, and the noise signal may be identified as a particle. In this embodiment, the kinetic particle size spectrometer is provided to perform temperature control on the light source, and a light source monitoring unit is added to realize the function of real-time monitoring. The light source signal is detected by the APD at the light source end. In this way, the changes of the light source can be fed back to the operation unit, and the feedback light source detection signal (first voltage information) is coherently calculated with the scattered light detection signal of the APD and PMT at the subsequent chamber end, thereby improving the signal-to-noise ratio, increasing the resolution and detection sensitivity, and ensuring the stability of the aerodynamic particle size spectrum.

[0043] A stray light filtering unit is used to split the converged light beam to form two parallel light beams along the X axis with equal spacing on the Y axis at the focus of the light in the sample chamber, filter out the stray light of the parallel light beam, and output the parallel light beam with the stray light filtered out into the sample chamber through the isolation unit; In this embodiment, as an optional embodiment, the stray light filtering unit includes: a beam splitting crystal 009 and an aperture 010, wherein: The beam splitting crystal 009 is used to split the converged light beam to form two parallel light beams along the X axis with equal spacing along the Y axis at the focus of the light beam, wherein the X axis direction is the direction connecting the center point of the laser, the paddle, the concave lens, the first convex lens, the second convex lens, and the beam splitting crystal, and the Y axis direction is the direction perpendicular to the X axis direction; In this embodiment, as an optional embodiment, the beam splitting crystal is a calcite beam splitter. The beam splitting crystal is used to separate the X-axis horizontal component energy and the Y-axis vertical component energy of the input linearly polarized light (convergent light beam), wherein the beam splitting distance is related to the wavelength of the light and the thickness of the beam splitting crystal. For example, for 630nm red light incident, the beam splitting distance of a 1mm thick calcite beam splitter is about 100um. After the convergent light beam is transmitted through the calcite beam splitter, two parallel light beams of equal brightness and equal spacing are output.

[0044] In this embodiment, after the convergent light beam passes through the calcite beam splitter, the polarized light of the X-axis will not be displaced, but due to the increase in the optical path, the polarized light of the Y-axis will be displaced by a certain distance, thereby forming two parallel light beams with a certain splitting distance on the Y-axis (for example, for a calcite beam splitter with a thickness of 1 mm, the splitting distance is about 100 um) but the propagation direction does not change, that is, after passing through the calcite beam splitter, the convergent light beam can form two parallel light beams along the X-axis with equal spacing on the Y-axis at the focus of the light in the sample chamber, wherein the width of the parallel light beam is 4-5 mm, the height (the vertical distance between the centers of the two parallel light beams) is about 100 um, and the light intensity distribution of the single parallel light beam presents a normal distribution on the Y-axis.

[0045] The aperture 010 is used to perform multi-stage stray light filtering on the parallel light beam, and output the parallel light beam after the stray light is filtered out to the sample chamber through the isolation unit.

[0046] Figure 2 Schematic diagram of the aperture structure provided by an embodiment of the present invention. Figure 2 As shown, in this embodiment, as an optional embodiment, the aperture 010 is a rectangular slit aperture, including a first-stage rectangular slit aperture 020, a second-stage rectangular slit aperture 021 and a third-stage rectangular slit aperture 022 connected in sequence, wherein the distance between adjacent rectangular slit apertures is 5 mm, and the slit width is 1 mm. After the two focused parallel light beams pass through the three-stage rectangular slit apertures of 1 mm×5 mm with a spacing of 5 mm, they pass through the isolation unit, such as the first window mirror 011, and then enter the gap between the air inlet 023 and the air outlet 024 in the sample chamber, wherein the three-stage rectangular slit aperture is used to filter stray light, so that the parallel light beams entering the sample chamber have good directionality and reduce scattered light caused by the optical path. In this way, by using multiple slit apertures of the same size, when the parallel light beam passes through the first slit aperture, the diffracted light or scattered light generated by the first slit aperture will be shielded by the second slit aperture. Since the size of the main light beam (parallel light beam) is equivalent to the slit, the second slit aperture can shield a large amount of diffracted light, and a small amount of diffracted light will be generated to enter the third slit aperture. In this way, after passing through the third slit aperture, the diffracted light will be greatly reduced. By using multiple slit apertures, the diffracted light caused by the slit edge of the parallel light beam can be effectively reduced.

[0047] In this embodiment, by arranging a multi-stage slit aperture at the light entrance of the sample chamber, the stray light diffracted by the pinhole is effectively reduced.

[0048] In this embodiment, in order to shield the stray light of the light source, a slit is set at the light input port (light entrance) of the sample chamber. The slit can effectively filter out the stray light caused by the optical system and control the light beam quality. However, since the light beam will be scattered when it is irradiated on the edge of the slit, the diffracted light will be scattered in the chamber of the sample chamber. After irradiating the jet column and other components in the chamber, strong diffuse reflection light will occur, which will be coupled to the detector and affect the detection result. In order to suppress the scattered light of the slit, this embodiment improves the optical path structure and nests multiple slit apertures to effectively reduce the scattered light entering the chamber, thereby reducing the background light noise in the chamber.

[0049] In this embodiment, the laser light source output by the aerodynamic particle size spectrometer is split into two parallel light beams separated by 100um in the Y-axis direction. The parallel light beams are input into the chamber in the sample chamber after passing through the slit, and irradiate the particles to cause scattering during the falling process of the particles. In the related art, since only one slit is designed in front of the entrance of the chamber, a large amount of derivative light enters the chamber, thereby irradiating the airflow nozzle and airflow absorption head in the chamber for driving the particles, causing diffuse reflection, increasing the background noise of the APD detector, and thus affecting the accuracy and sensitivity of the particle size spectrometer.

[0050] An isolation unit, comprising a first window mirror 011 and a second window mirror 012, wherein the first window mirror 011 is connected to the aperture 010 and is used to isolate the sample chamber from the beam generating and shaping unit, or the sample chamber from the stray light filtering unit, so as to prevent the gas to be detected with particles in the sample chamber from contaminating the optical path environment of the beam generating and shaping unit and the stray light filtering unit, and the second window mirror 012 is used to isolate the sample chamber from the avalanche photodiode detector 11, and the sample chamber from the photomultiplier tube detector 12; In this embodiment, the first window mirror is used to isolate the sample chamber from the light path generation shaping unit and the stray light filtering unit, so that the gas to be detected with particulate matter in the sample chamber will not pollute the light path environment of the light path generation unit and the stray light filtering unit; the two parallel light beams passing through the first window mirror will be focused at the light focus in the middle of the air inlet and the air outlet of the sample chamber, and the light focus has a certain distance interval on the Y axis (the direction of particle movement), which serves as the convergence focus of the two parallel light beams.

[0051] The sample chamber is used to input the sample to be tested. When the sample to be tested falls to the focus of the two parallel light beams, it is irradiated by the two parallel light beams and diffusely reflects with the particles contained in the sample to be tested. After the lateral diffuse reflection light beams are converged, they are input to the avalanche photodiode detector. After the forward diffuse reflection light beams are converged, they are input to the photomultiplier tube detector. Figure 3 A schematic diagram of the main structure of a sample chamber provided in an embodiment of the present invention; Figure 4 A schematic diagram of the side view structure of the sample chamber provided in an embodiment of the present invention; Figure 5 Another schematic diagram of the main structure of the sample chamber provided by the embodiment of the present invention. Figures 3 to 5 As shown, in this embodiment, as an optional embodiment, the sample chamber includes: an aerodynamic gas nozzle 013, a second concave mirror 014, a focusing lens 015, a fourth convex lens 016 and a chamber 025, wherein, Figure 6 Schematic diagram of the aerodynamic gas nozzle structure provided by an embodiment of the present invention. Figures 3 to 6 As shown, the aerodynamic gas nozzle 013 is used to input the sample to be tested into the chamber 025. When the sample to be tested falls to the focus of the light in the chamber, two parallel light beams, namely the split O light 018 and the split E light 019, which pass through the stray light filtering unit, irradiate the particles 020 in the sample to be tested, and diffuse reflection occurs in the chamber 025 to form a lateral diffuse reflection light beam and a forward diffuse reflection light beam. The sample to be tested is the gas to be tested. Before the gas to be tested is input, it is verified by inputting a particle-free sheath gas. As an optional embodiment, the aerodynamic gas nozzle is a sheath-type nozzle, including but not limited to: a sheath-type nozzle outer nozzle 61 and a sheath-type nozzle inner nozzle 62, wherein the sheath-type nozzle outer nozzle 61 has an inner diameter of 6 mm, the sheath-type nozzle outer nozzle opening 63 has a diameter of 1.1 mm, the sheath-type nozzle inner nozzle 62 has an inner diameter of 2 mm, the sheath-type nozzle inner nozzle opening 64 has a diameter of 0.8 mm, and the interval 65 between the sheath-type nozzle outer nozzle and the sheath-type nozzle inner nozzle is 1 mm.

[0052] In this embodiment, the two parallel light beams filtered by the stray light filtering unit are focused at a position between the air inlet and the air outlet of the aerodynamic gas nozzle (light focus), and the focused light foci are spaced apart on the Y axis.

[0053] The second concave mirror 014 is disposed at a lateral position in the chamber 025 to converge the lateral diffuse reflection light beam received from the sample to be tested to the focusing lens 015; In this embodiment, as an optional embodiment, the second concave mirror is located at a lateral position in the chamber at the same height as the parallel light beam.

[0054] The focusing lens 015 focuses the lateral diffusely reflected light gathered by the second concave mirror 014 and inputs the focused light to the avalanche photodiode detector 11; The fourth convex lens 016 is disposed at a forward position in the chamber 025 , and converges the forward diffuse reflection light beam received from the sample to be tested to the photomultiplier tube detector 12 .

[0055] In this embodiment, as an optional embodiment, the focusing lens and the second concave mirror are located on the same side.

[0056] In this embodiment, when particulate matter falls from the air inlet and passes through the focal points of the two parallel light beams respectively, the two parallel light beams are irradiated on the particulate matter and scattered. At the two focal points, scattered light (diffuse reflection light beam) of a certain intensity is emitted to the outside. A part of the side scattered light (side diffuse reflection light beam) is focused by the second side concave mirror, i.e., the concave mirror and the focusing lens, and then detected by the other side rear end APD, i.e., the APD detector, thereby forming two photocurrent pulses (light intensity information) with a certain time interval, which are converted into voltage information and output to the operation unit. After circuit processing and analysis by the operation unit, the size and other characteristics of the particulate matter can be obtained.

[0057] The avalanche photodiode detector 11 is used to detect the second light intensity information of the lateral diffusely reflected light beam, obtain the second voltage information after transformation, and output it to the operation unit; The photomultiplier tube detector 12 is used to detect the third light intensity information of the forward diffuse reflection light beam, obtain the third voltage information after transformation, and output it to the operation unit; In this embodiment, the avalanche photodiode detector is a back-end APD, which detects the light scattering peak information (second light intensity information) of the scattered light signal of the diffuse reflection light beam (lateral diffuse reflection light beam) input from the focusing lens, and transforms the detected light scattering peak information and outputs it to the operation unit. As another optional embodiment, the avalanche photodiode detector can also output the detected light scattering peak information to the operation unit, and the operation unit performs corresponding transformation.

[0058] In this embodiment, as an optional embodiment, the rear end APD is located on the other side opposite to the second concave mirror.

[0059] In this embodiment, as an optional embodiment, the device further includes: The filter assembly is used to perform extinction processing on the other parallel light beams among the two parallel light beams except for the parallel light beams irradiating the particles in the sample to be measured.

[0060] In this embodiment, as an optional embodiment, the filter assembly can be arranged in the sample chamber, including: a first neutral density filter 017 and a second neutral density filter 018, wherein: The first neutral density filter 017 is installed on the optical path of the parallel light beam at a preset Brewster angle, absorbs the incident horizontally polarized parallel light beam and part of the vertically polarized parallel light beam, and reflects the other part of the vertically polarized parallel light beam that is not absorbed to the second neutral density filter 018; The second neutral density filter 018 is arranged spatially relative to the first neutral density filter 017 and rotated 90° in the vertical light path propagation direction to absorb another part of the incident vertically polarized parallel light beam.

[0061] In this embodiment, as an optional embodiment, the first neutral density filter with a reflector function is arranged at the center position of the fourth convex lens, which can reflect and absorb the parallel light beam to prevent the parallel light beam from directly entering the target surface of the PMT detector. The receiving surface of the fourth convex lens that is not blocked by the reflector (the first neutral density filter) can focus the forward scattered light of the particulate matter onto the detection surface of the PMT detector, thereby achieving the maximum reception of the forward scattered light of the particulate matter.

[0062] In this embodiment, the parallel light beam passes through the first neutral density filter installed on the optical path at a preset Brewster angle. The first neutral density filter will theoretically absorb 100% of the horizontally polarized parallel light beam and part of the vertically polarized parallel light beam, and reflect the remaining vertically polarized parallel light beam to the second neutral density filter. The second neutral density filter is spatially rotated 90° in the vertical optical path propagation direction relative to the first neutral density filter, that is, it is located on the optical path of another part of the vertically polarized parallel light beam, and at the same time meets the installation angle of the Brewster angle, so it can achieve 100% absorption of vertically polarized light. Therefore, through the absorption filtering of the two-stage polarization filter, the maximum degree of extinction can be achieved. That is, after the parallel light beam passes through the light focus and irradiates the particles, it will diverge and continue to propagate along the light beam direction to irradiate the rear convex lens, that is, the neutral density filter installed at the Brewster angle on the fourth convex lens. The neutral density filter can achieve complete absorption of polarized light on the X axis and partial absorption of polarized light on the Y axis, and at the same time reflect the unabsorbed Y-axis polarized light to another neutral density filter installed at the Brewster angle, achieving complete absorption of Y-axis polarized light again, thereby achieving complete extinction of the parallel light beam in the sample chamber.

[0063] In this embodiment, the extinction chamber composed of a filter assembly is designed for polarized light, which can theoretically absorb 100% of the laser energy, thereby effectively improving the extinction efficiency and reducing light reflection.

[0064] In this embodiment, as another optional embodiment, black Teflon matte material may be coated on the sample chamber and the filter assembly to minimize diffuse reflection of the parallel light beam, thereby increasing the signal-to-noise ratio.

[0065] Figure 7 Schematic diagram of calculating Brewster angle provided by an embodiment of the present invention. Figure 7 As shown, in this embodiment, as an optional embodiment, the Brewster angle is calculated using the following formula:

[0066]

[0067] In the formula, is Brewster's angle, is the refractive index of the filter assembly (first neutral density filter or second neutral density filter), is the refractive index of air.

[0068] In this embodiment, the filter assembly forms a laser absorption extinction chamber to reduce light rebound.

[0069] A calculation unit is used to receive the first light intensity information, the second light intensity information and the third light intensity information, and to perform a coherent calculation on the first light intensity information and the second light intensity information according to a preset coherent algorithm to obtain effective information detected by the APD, and to perform a coherent calculation on the first light intensity information and the third light intensity information to obtain effective information detected by the PMT;

[0070] According to the signal-to-noise ratio of the effective information detected by the APD, it is determined whether the effective information detected by the APD or the effective information detected by the PMT is used for particle analysis, wherein the particle analysis includes: particle concentration of particle size corresponding to the particle size distribution.

[0071] In this embodiment, as an optional embodiment, the coherent operation is to perform dynamic differential calculation based on the first light intensity information obtained by the light source monitoring unit, the second light intensity information obtained by the avalanche photodiode detector, and the third light intensity information obtained by the photomultiplier tube detector, so as to calculate the multiplication factor for light intensity correction through calibration.

[0072] In this embodiment, whether it is Mie scattering or Rayleigh scattering, the side scattered light is relatively small, so the APD installed on the side can receive a certain intensity of light scattering signal and is not easy to saturate. However, due to the problem of the light scattering angle of tiny particles and the low sensitivity of APD, the APD detector cannot detect the scattered light emitted by tiny particles when passing through the parallel light beam, so it cannot provide effective data to the back-end processing method, resulting in the inability to identify tiny particles. In this embodiment, the PMT detector is installed in the direction of the forward scattering of the particle size of the stronger scattered light in the aerodynamic particle size spectrometer. At the same time, the PMT detector can detect the scattered light of tiny particles due to its high gain. At the same time, it is easy to saturate for large particles, resulting in the inability to output effective signals normally. In this embodiment, based on the above characteristics, the data after coherent operation of the output of the APD detector and the PMT detector are fused through a pre-set algorithm, and the signal-to-noise ratio (SNR) of the output signal of the APD detector is used as a measurement benchmark. Specifically, as an optional embodiment, according to the signal-to-noise ratio of the APD detection effective information, it is determined to use the APD detection effective information or the PMT detection effective information for particle analysis, including:

[0073] Determine that the signal-to-noise ratio of the effective information detected by the APD is greater than or equal to the first signal-to-noise ratio threshold and the effective information detected by the APD is not saturated, and the APD is used to detect the effective information for conventional peak time difference detection; or, if the signal-to-noise ratio of the effective information detected by the APD is less than the first signal-to-noise ratio threshold, the signal-to-noise ratio of the effective information detected by the PMT is greater than or equal to the second signal-to-noise ratio threshold and the effective information detected by the PMT is not saturated, and the PMT is used to detect the effective information for conventional peak time difference detection, so as to perform particle analysis based on the conventional peak time difference detection result;

[0074] Determine that the signal-to-noise ratio of effective information detected by APD is greater than or equal to the first signal-to-noise ratio threshold and the effective information detected by APD is saturated, calculate the peak difference at the middle moment of the effective information detected by APD to replace the peak time difference, or, if the signal-to-noise ratio of effective information detected by APD is less than the first signal-to-noise ratio threshold, the signal-to-noise ratio of effective information detected by PMT is greater than or equal to the second signal-to-noise ratio threshold, and the effective information detected by PMT is saturated, calculate the peak difference at the middle moment of the effective information detected by PMT to replace the peak time difference, so as to perform particle analysis based on the replaced peak time difference detection result.

[0075] In this embodiment, as an optional embodiment, when the signal-to-noise ratio of the APD detection effective information is less than the first signal-to-noise ratio threshold and the signal-to-noise ratio of the PMT detection effective information is less than the second signal-to-noise ratio threshold, the PMT detection effective information is considered invalid and peak time difference detection is not performed.

[0076] In this embodiment, as an optional embodiment, the first signal-to-noise ratio threshold is 10 dB, and the second signal-to-noise ratio threshold is 6 dB, which is not limited in this embodiment.

[0077] In this embodiment, due to factors such as the circuit, optical path structure, and sensor production process, the signals output by the light source monitoring unit, the APD detector, and the PMT detector will have certain noise. In order to effectively reduce the influence of the noise, the operation unit is also used to:

[0078] After receiving the first light intensity information, the second light intensity information and the third light intensity information, before performing coherent operations on the first light intensity information and the second light intensity information respectively according to a preset coherent algorithm, the first light intensity information, the second light intensity information and the third light intensity information are filtered using a preset filtering algorithm.

[0079] In this embodiment, a filtering algorithm is set in the operation unit to filter the output signal of the detector to filter out the stray noise in the output signal, improve the resolution accuracy of the peak value, and realize the detection of the peak time difference. As an optional embodiment, the filtering algorithm is based on a FIR low-pass filter and dynamic adaptive parameter adjustment to realize adaptive filtering of signals under different circumstances.

[0080] In this embodiment, when the particles fall through the focus of the two parallel light beams, the two parallel light beams are incident on the particles and emit scattered light of a certain intensity, wherein the scattered light includes forward scattered light, side scattered light and backward scattered light. Of the scattered light emitted through the focus of the two parallel light beams, a portion of the forward scattered light is focused by the forward lens and detected by the forward PMT detector, thereby forming two photocurrent pulse outputs with a certain time interval, which are then processed and analyzed by the subsequent circuit to obtain the size and other characteristics of the particles.

[0081] In this embodiment, the PMT detector has better sensitivity than the front-end APD detector, and can detect weak scattered light from tiny particles that the APD detector cannot detect.

[0082] In this embodiment, the aerodynamic method involves the principles of aerodynamics, polarized laser optics, time of flight and light scattering. Particles of different diameters have different speeds in the high-speed jet airflow under the action of the aerodynamic air path structure. Under the action of the high-speed jet airflow, large particles have a lower speed and small particles have a higher speed. Since the laser emitted by the polarized laser has good linear polarization characteristics, the laser rotates a certain angle through the wave plate and enters the beam splitter crystal again after shaping. The polarized light passes through the crystal in a straight line relative to the horizontal light (O light) of the beam splitter crystal, and the vertical light (E light) will be offset by a certain distance to be emitted. The offset depends on the wavelength of the light and the length of the crystal. Therefore, the polarized laser can be used to split the output light.

[0083] Figure 8 Schematic diagram of particle analysis principle provided by an embodiment of the present invention. Figure 8 As shown, in this embodiment, when the particles ejected at high speed pass through a parallel light beam at a certain distance, scattering occurs, and a photoelectric detector located at a non-direct angle of the light, such as a PMT detector, receives the scattered light signal, and converts the scattered light signal into an electrical signal for collection and processing by the back-end circuit. The longer the particles fly through the parallel light beam, the wider the peak-to-peak interval of the light scattering peaks of the scattered light signal obtained by the photoelectric detector. Conversely, the smaller the peak-to-peak time interval of the light scattering peaks of the scattered light signal obtained by the detector. In this way, the aerodynamic diameter of the particle can be obtained through the peak-to-peak time interval. At the same time, by judging the peak-to-peak value, the light scattering characteristics of the particle size can also be judged, which helps to further analyze other characteristics of the particle.

[0084] In this embodiment, by adding a PMT detector to the aerodynamic particle size spectrometer, the APD detector and the PMT detector are used in combination to solve the technical problem of low sensitivity of the APD detector. That is, by combining the PMT detector and the APD detector, the APD detector is used to detect the side scattered light of large particles in the dynamic particle size spectrometer, and the PMT detector is used to detect the forward scattered light of Mie scattering of small particles in the dynamic particle size spectrometer, so that continuous real-time statistical analysis of particles ranging from tens of nanometers to hundreds of microns can be achieved.

[0085] Fig. 9 A schematic diagram of a particle analysis method based on particle size spectrum provided in an embodiment of the present invention. Fig. 9 As shown, the above device is used to perform particle analysis, and the method includes:

[0086] S101, turning on the particle analysis device, introducing zero gas after self-checking, obtaining an optimal APD coefficient based on first light intensity information of the light source monitoring unit and second light intensity information of the avalanche photodiode detector, and obtaining an optimal PMT coefficient based on first light intensity information of the light source monitoring unit and third light intensity information of the photomultiplier tube detector;

[0087] In this embodiment, the first light intensity information is the light source APD measurement value, the second light intensity information is the light dispersion APD measurement value, and the third light intensity information is the light dispersion PMT measurement value. The light source monitoring unit is called the light source end ADP, the avalanche photodiode detector is called the front-end ADP, and the photomultiplier tube detector is called the back-end PMT.

[0088] In this embodiment, after the particle analysis device (equipment) is turned on, data collection and measurement are performed using the ADP at the light source end, the front-end APD, and the rear-end PMT under the condition of introducing zero gas. Since the output data intensity of the APD at the light source end is linearly correlated with the output data intensity of the front-end APD and the output data intensity of the rear-end PMT, the light-scattering APD measurement value is subtracted from the light-source APD measurement value multiplied by the APD coefficient to obtain the APD effective value (error), and the APD coefficient corresponding to the minimum APD effective value is obtained to obtain the optimal APD coefficient.

[0089] In this embodiment, the optimal APD coefficient is calculated using the following formula:

[0090]

[0091] In the formula, is the APD coefficient, is the light-scattering APD measurement value, is the light source APD measurement value. In this embodiment, Corresponding is the optimal APD coefficient, that is .

[0092] In this embodiment, by changing the APD coefficient When the effective value of the calculated result is the smallest, the corresponding APD coefficient is the optimal APD coefficient, and the optimal APD coefficient is saved.

[0093] In this embodiment, the light source APD measurement value multiplied by the PMT coefficient is subtracted from the light dispersion PMT measurement value to obtain the PMT effective value, and the PMT coefficient corresponding to the minimum PMT effective value is obtained to obtain the optimal PMT coefficient.

[0094] In this embodiment, the optimal APD coefficient is calculated using the following formula:

[0095]

[0096] In the formula, Corresponding is the optimal PMT coefficient, that is , is the PMT coefficient, is the light scattering PMT measurement value.

[0097] S102, introducing sample gas, obtaining a first light scattering APD based on first light intensity information of the light source monitoring unit, second light intensity information of the avalanche photodiode detector and an optimal APD coefficient, and obtaining a second light scattering APD based on first light intensity information of the light source monitoring unit, third light intensity information of the photomultiplier tube detector and an optimal PMT coefficient;

[0098] In this embodiment, the first light scattering APD is obtained based on the light source APD measurement value of the light source end APD, the light scattering APD measurement value of the front-end APD and the optimal APD coefficient, and the second light scattering APD is obtained based on the light source APD measurement value of the light source end APD, the light scattering PMT measurement value of the back-end PMT and the optimal PMT coefficient.

[0099] In this embodiment, a sample gas (gas containing particles to be measured) is introduced into the device, and the scattered light measurement results obtained are:

[0100]

[0101]

[0102] In the formula, is the scattered light APD measurement result, namely the first light scattered APD, It is the scattered light PMT measurement result, namely the second light scattering APD.

[0103] S103, calculating the signal-to-noise ratio of the first light-scattering APD and the signal-to-noise ratio of the second light-scattering APD respectively based on a preset signal-to-noise ratio calculation formula;

[0104] In this embodiment, the signal-to-noise ratio is calculated using the following formula:

[0105] SNR=20×log10(Vs / Vn)

[0106] Where SNR is the signal-to-noise ratio, Vs is the maximum value of the detector output signal (first light scattering APD), and Vn is the maximum value of the detector output noise when there is no light signal (only zero gas is introduced).

[0107] S104 , based on the signal-to-noise ratio of the first light-scattering APD, the signal-to-noise ratio of the second light-scattering APD, and a preset signal-to-noise ratio threshold, determine a light-scattering APD for particle analysis from the first light-scattering APD and the second light-scattering APD.

[0108] In this embodiment, after the device is turned on and passes the self-test, zero gas (filtered clean air or high-purity nitrogen) is introduced, and then the maximum noise of the side scattering APD and the forward scattering PMT is detected; the gas to be tested (sample gas) is introduced, and the maximum value of the scattered light of the front-end APD and the rear-end PMT after particles of different particle sizes enter the particle analysis device is measured; the signal-to-noise ratio (SNR) of the front-end APD and the rear-end PMT is calculated in real time; and then the signal-to-noise ratio (SNR) of the front-end APD output signal is used as the measurement benchmark:

[0109] When the signal-to-noise ratio of the APD output signal is greater than or equal to 10 dB and the APD output signal is not saturated, the signal output by the APD is used for conventional peak time difference detection;

[0110] When the signal-to-noise ratio of the APD output signal is greater than or equal to 10 dB and the APD output signal is saturated, the peak time difference is replaced by calculating the peak difference at the middle moment of the saturation value of the APD output signal;

[0111] When the APD output signal signal-to-noise ratio is less than 10dB and the PMT output signal is not saturated and the signal-to-noise ratio is greater than or equal to 6dB, the PMT signal is used for conventional peak time difference detection;

[0112] When the signal-to-noise ratio of the APD output signal is less than 10dB and the PMT output signal is saturated and the signal-to-noise ratio is greater than or equal to 6dB, the peak time difference is replaced by calculating the peak difference at the middle moment of the saturation value of the PMT output signal;

[0113] When the APD output signal signal-to-noise ratio is less than 10 dB and the PMT signal signal-to-noise ratio is less than 6 dB, the PMT output signal is considered invalid and the peak time difference detection is not performed.

[0114] Fig.10 Another schematic diagram of a particle analysis method based on particle size spectrum provided by an embodiment of the present invention. Fig.10As shown, the method includes:

[0115] S201, perform self-inspection on the particle analysis device, if the self-inspection passes;

[0116] S202, introduce zero gas;

[0117] S203, wait for 30 minutes;

[0118] S204, collecting APD and PMT signals;

[0119] S205, filtering using an adaptive parameter FIR filter;

[0120] S206, measuring data for a certain period of time, if the measurement time is not met, returning to step S204;

[0121] S207, calculating the maximum value of APD and PMT noise;

[0122] S208, introducing sample gas;

[0123] S209, collecting APD and PMT signals;

[0124] S210, filtering using an adaptive parameter FIR filter;

[0125] S211, measuring data for a certain period of time. If the measurement time is not met, returning to step S209;

[0126] S212, measuring the maximum values ​​of APD and PMT signals;

[0127] S213, calculating the signal-to-noise ratio of the APD and PMT;

[0128] S214, if APD SNR≥10dB and APD is not saturated, execute step S215;

[0129] S215, APD peak time difference method;

[0130] S216, if APD SNR≥10dB and APD is saturated, execute step S217;

[0131] S217, APD saturation region median time difference method;

[0132] S218, if APD SNR<10dB, PMT SNR≥6dB and PMT is not saturated, execute step S219;

[0133] S219, PMT peak time difference method;

[0134] S220, if APD SNR<10dB, PMT SNR≥6dB and PMT is saturated, execute step S221;

[0135] S221, PMT saturation region median time difference method;

[0136] S222, if APD SNR<10dB, PMT SNR<6dB and PMT is not saturated, execute step S223;

[0137] S223, do not detect time difference;

[0138] S224, store the calculation results and return to step S208.

[0139] Fig.11 Another schematic diagram of a particle analysis method based on particle size spectrum provided by an embodiment of the present invention. Fig.11 As shown, the method includes:

[0140] S301, perform self-inspection on the particle analysis device, if the self-inspection passes;

[0141] S302, introduce zero gas;

[0142] S303, obtain initialization and ;

[0143] S304, wait for 30 minutes;

[0144] S305, measuring the light source APD and scattered light APD measurement values;

[0145] S306, filtering using an adaptive parameter FIR filter;

[0146] S307, measuring data for a certain period of time;

[0147] S308, calculate ( )’s effective value;

[0148] S309, determine whether the effective value is the minimum, if so, execute step S310, if not, change , return to step S305;

[0149] S310, storage record ;

[0150] S311, measuring the light source APD and scattered light PMT measurement values;

[0151] S312, filtering using an adaptive parameter FIR filter;

[0152] S313, measuring data for a certain period of time;

[0153] S314, calculate ( )’s effective value;

[0154] S315, determine whether the effective value is the minimum, if so, execute step S316, if not, change , return to step S311;

[0155] S316, storage record ;

[0156] S317, confirming that the calibration is completed;

[0157] S318, introducing sample gas;

[0158] S319, calculate the light dispersion APD: ;

[0159] S320, calculate light dispersion PMT: ;

[0160] S321, fusion calculation of light scattering APD and light scattering PMT.

[0161] In this embodiment, the above implementation process is combined to achieve a sample chamber measurement environment with extremely low background stray light. At the same time, the use of high-quality equally spaced focused parallel light can increase the light energy irradiating the particles, increase the signal-to-noise ratio, and improve the resolution. It can also increase the incident area of ​​the particles, reduce the escape of the particles, increase the detection probability, and improve the dynamic range. Therefore, the present invention has achieved good results and achieved the intended purpose through actual measurement and verification for the design of broadening the dynamic range and resolution of the particle size spectrometer.

[0162] Based on the same inventive concept, an embodiment of the present invention further provides a storage medium on which a computer program is stored. When the program is executed by a processor, the steps of the particle analysis method based on particle size spectrum in any possible implementation manner described above are implemented.

[0163] Alternatively, the storage medium may be a non-transitory computer-readable storage medium, for example, the non-transitory computer-readable storage medium may be a ROM, a random access memory (RAM), a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like.

[0164] Based on the same inventive concept, see Fig.12The embodiment of the present invention also provides an electronic device, including a memory 101 (such as a non-volatile memory), a processor 102, and a computer program stored in the memory 101 and executable on the processor 102. When the processor 102 executes the program, the steps of the particle analysis method based on the particle size spectrum in any possible implementation method described above are implemented, which can be equivalent to the particle analysis device based on the particle size spectrum as described above. Of course, the processor can also be used to process other data or operations. The electronic device can be a PC, a server, a terminal, and other devices.

[0165] like Fig.12 As shown, the electronic device may also generally include: a memory 103, a network interface 104, and an internal bus 105. In addition to these components, other hardware may also be included, which will not be described in detail.

[0166] It should be pointed out that the above-mentioned particle analysis device based on particle size spectrum can be realized by software. As a device in a logical sense, it is formed by the processor 102 of the electronic device in which it is located reading the computer program instructions stored in the non-volatile memory into the memory 103 for execution.

[0167] The embodiments of the subject matter and functional operations described in this specification may be implemented in the following: digital electronic circuits, tangibly embodied computer software or firmware, computer hardware including the structures disclosed in this specification and their structural equivalents, or a combination of one or more of them. The embodiments of the subject matter described in this specification may be implemented as one or more computer programs, i.e., one or more modules in computer program instructions encoded on a tangible non-temporary program carrier to be executed by a data processing device or to control the operation of the data processing device. Alternatively or additionally, the program instructions may be encoded on an artificially generated propagation signal, such as a machine-generated electrical, optical or electromagnetic signal, which is generated to encode information and transmit it to a suitable receiver device for execution by a data processing device. The computer storage medium may be a machine-readable storage device, a machine-readable storage substrate, a random or serial access memory device, or a combination of one or more of them.

[0168] The processes and logic flows described in this specification can be performed by one or more programmable computers executing one or more computer programs to perform corresponding functions by operating on input data and generating output. The processes and logic flows can also be performed by special purpose logic circuits, such as FPGAs (field programmable gate arrays) or ASICs (application-specific integrated circuits), and the apparatus can also be implemented as special purpose logic circuits.

[0169] Computers suitable for executing computer programs include, for example, general and / or special microprocessors, or any other type of central processing unit. Typically, the central processing unit will receive instructions and data from a read-only memory and / or a random access memory. The basic components of a computer include a central processing unit for implementing or executing instructions and one or more memory devices for storing instructions and data. Typically, a computer will also include one or more large-capacity storage devices for storing data, such as a disk, a magneto-optical disk, or an optical disk, or the computer will be operably coupled to this large-capacity storage device to receive data from it or to transmit data to it, or both. However, a computer does not necessarily have such a device. In addition, a computer can be embedded in another device, such as a mobile phone, a personal digital assistant (PDA), a mobile audio or video player, a game console, a global positioning system (GPS) receiver, or a portable storage device such as a universal serial bus (USB) flash drive, to name a few.

[0170] Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including, for example, semiconductor memory devices (e.g., EPROM, EEPROM and flash memory devices), magnetic disks (e.g., internal hard disks or removable disks), magneto-optical disks, and CD-ROM and DVD-ROM disks. The processor and memory may be supplemented by, or incorporated in, special purpose logic circuitry.

[0171] Although this specification includes many specific implementation details, these should not be interpreted as limiting the scope of any invention or the scope of protection claimed, but are mainly used to describe the features of the specific embodiments of specific inventions. Certain features described in multiple embodiments in this specification may also be implemented in combination in a single embodiment. On the other hand, the various features described in a single embodiment may also be implemented separately in multiple embodiments or in any suitable sub-combination. In addition, although the features may work as above in certain combinations and even initially claim protection, one or more features from the claimed combination may be removed from the combination in some cases, and the claimed combination may point to a sub-combination or a variation of a sub-combination.

[0172] Similarly, although operations are depicted in a particular order in the accompanying drawings, this should not be understood as requiring that these operations be performed in the particular order shown or performed sequentially, or requiring that all illustrated operations be performed to achieve the desired results. In some cases, multitasking and parallel processing may be advantageous. In addition, the separation of various system modules and components in the above-described embodiments should not be understood as requiring such separation in all embodiments, and it should be understood that the described program components and systems can generally be integrated together in a single software product, or packaged into multiple software products.

[0173] Thus, specific embodiments of the subject matter have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions recited in the claims can be performed in a different order and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the particular order or sequential order shown to achieve the desired results. In some implementations, multitasking and parallel processing may be advantageous.

[0174] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0175] The above is only a specific embodiment of the present invention, so that those skilled in the art can understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A particle analysis device based on particle size spectrum, characterized in that: include: A beam forming and shaping unit, a light source monitoring unit, a stray light filtering unit, an isolation unit, a sample chamber, an avalanche photodiode detector, a photomultiplier tube detector and a computing unit, wherein: A beam generation and shaping unit is used to excite the first linear polarized light of the collimated light, adjust the polarization state of the first linear polarized light to the second linear polarized light with the same energy of the horizontal component and the vertical component, expand the second linear polarized light, and then split it according to a preset splitting ratio to obtain a first laser beam and a second laser beam, output the first laser beam to the light source monitoring unit, and converge the second laser beam to form a converged beam and output it to the stray light filtering unit, wherein the laser energy of the first laser beam is less than the laser energy of the second laser beam; A light source monitoring unit, used for detecting first light intensity information of the first laser beam, obtaining first voltage information after transformation, and outputting the first voltage information to the operation unit; A stray light filtering unit is used to split the converged light beam to form two parallel light beams along the X axis with equal spacing on the Y axis at the focus of the light in the sample chamber, filter out the stray light of the parallel light beam, and output the parallel light beam with the stray light filtered out into the sample chamber through the isolation unit; The isolation unit includes a first window mirror and a second window mirror, wherein the first window mirror is connected to the aperture and is used to isolate the sample chamber from the beam generating and shaping unit, or the sample chamber from the stray light filtering unit, so as to prevent the gas to be detected with particles in the sample chamber from contaminating the optical path environment of the beam generating and shaping unit and the stray light filtering unit, and the second window mirror is used to isolate the sample chamber from the avalanche photodiode detector, and the sample chamber from the photomultiplier tube detector, respectively; The sample chamber is used to input the sample to be tested. When the sample to be tested falls to the focus of the two parallel light beams, it is irradiated by the two parallel light beams and diffusely reflects with the particles contained in the sample to be tested. After the lateral diffuse reflection light beams are converged, they are input to the avalanche photodiode detector. After the forward diffuse reflection light beams are converged, they are input to the photomultiplier tube detector. An avalanche photodiode detector is used to detect the second light intensity information of the lateral diffusely reflected light beam, obtain the second voltage information after transformation, and output it to the operation unit; A photomultiplier tube detector is used to detect the third light intensity information of the forward diffuse reflection light beam, obtain the third voltage information after transformation, and output it to the operation unit; A calculation unit is used to receive the first light intensity information, the second light intensity information and the third light intensity information, and to perform a coherent calculation on the first light intensity information and the second light intensity information according to a preset coherent algorithm to obtain effective information detected by the APD, and to perform a coherent calculation on the first light intensity information and the third light intensity information to obtain effective information detected by the PMT; According to the signal-to-noise ratio of the effective information detected by the APD, it is determined whether the effective information detected by the APD or the effective information detected by the PMT is used for particle analysis, wherein the particle analysis includes: particle concentration of particle size corresponding to the particle size distribution.

2. The particle analysis device based on particle size spectrum according to claim 1, characterized in that: The beam forming and shaping unit comprises: a laser, a paddle, a first concave lens, a first convex lens, a beam splitter, a second convex lens, and a third convex lens, wherein: A laser, used for exciting and outputting a first linear polarized light of the collimated light; A pick, connected to the laser, vertically receives the first linear polarized light emitted by the laser, adjusts the polarization state of the incident first linear polarized light so that the energy of the horizontal component is the same as the energy of the vertical component, obtains the second linear polarized light and outputs it; A first concave lens is connected to the pick and receives the second linearly polarized light output by the pick; A first convex lens is connected to the first concave lens, and the first concave lens and the first convex lens form a beam expander for expanding the incident second polarized light to obtain expanded light; A beam splitter is connected to the first convex lens and is used to split the expanded light to obtain a first laser beam reflected from the beam splitter and a second laser beam penetrating the beam splitter. The first laser beam is incident on the second convex lens, and after being converged by the second convex lens, it is incident on the light source monitoring unit. The second laser beam is incident on the third convex lens. The laser energy of the first laser beam is much smaller than the laser energy of the second laser beam. The third convex lens is connected to the beam splitter and is used to converge the second laser beam in the Y-axis direction representing the vertical component energy to obtain a converged beam, which is incident on the stray light filtering unit, wherein the horizontal component energy and the vertical component energy of the polarization state of the converged beam are the same.

3. The particle analysis device based on particle size spectrum according to claim 1, characterized in that: The stray light filtering unit comprises: a beam splitting crystal and an aperture, wherein: A beam splitting crystal is used to split the converged light beam to form two parallel light beams along the X axis with equal spacing along the Y axis at the focus of the light beam, wherein the X axis direction is the direction connecting the center point of the laser, the paddle, the concave lens, the first convex lens, the second convex lens, and the beam splitting crystal, and the Y axis direction is the direction perpendicular to the X axis direction; The aperture is used to perform multi-stage stray light filtering on the parallel light beam, and output the parallel light beam after the stray light is filtered out to the sample chamber through the isolation unit.

4. The particle analysis device based on particle size spectrum according to claim 3, characterized in that: The aperture is a rectangular slit aperture, including a first-stage rectangular slit aperture, a second-stage rectangular slit aperture and a third-stage rectangular slit aperture connected in sequence, wherein the distance between adjacent rectangular slit apertures is 5 mm, and the slit width is 1 mm.

5. The particle analysis device based on particle size spectrum according to claim 1, characterized in that: The sample chamber comprises: an aerodynamic gas nozzle, a second concave mirror, a focusing lens, a fourth convex lens and a chamber, wherein: The aerodynamic gas nozzle is used to input the sample to be tested into the chamber. When the sample to be tested falls to the focus of the light in the chamber, two parallel light beams passing through the stray light filtering unit illuminate the particles in the sample to be tested, and diffuse reflection occurs in the chamber to form a lateral diffuse reflection light beam and a forward diffuse reflection light beam. A second concave mirror is disposed at a lateral position in the chamber to converge the lateral diffuse reflection light beam received from the sample to be tested to the focusing lens; A focusing lens is used to focus the lateral diffusely reflected light gathered by the second concave mirror and then input it into the avalanche photodiode detector; The fourth convex lens is arranged at a forward position in the chamber, and converges the forward diffuse reflection light beam received from the sample to be tested to the photomultiplier tube detector.

6. The particle analysis device based on particle size spectrum according to any one of claims 1 to 5, characterized in that: Also includes: The filter assembly is used to perform extinction processing on the other parallel light beams among the two parallel light beams except for the parallel light beams irradiating the particles in the sample to be measured.

7. The particle analysis device based on particle size spectrum according to any one of claims 1 to 6, characterized in that: The filter assembly may be arranged in the sample chamber, comprising: a first neutral density filter and a second neutral density filter, wherein: The first neutral density filter is installed on the optical path of the parallel light beam at a preset Brewster angle, absorbs the incident horizontally polarized parallel light beam and part of the vertically polarized parallel light beam, and reflects another part of the vertically polarized parallel light beam that is not absorbed to the second neutral density filter; The second neutral density filter is arranged spatially relative to the first neutral density filter and rotated 90 degrees in the vertical light path propagation direction to absorb another part of the incident vertically polarized parallel light beam.

8. A particle analysis method based on particle size spectrum, characterized in that: Applied to the particle analysis device according to any one of claims 1 to 7, the particle analysis method based on particle size spectrum comprises: Turn on the particle analysis device, introduce zero gas after self-checking, obtain the optimal APD coefficient based on the first light intensity information of the light source monitoring unit and the second light intensity information of the avalanche photodiode detector, and obtain the optimal PMT coefficient based on the first light intensity information of the light source monitoring unit and the third light intensity information of the photomultiplier tube detector; Passing sample gas, obtaining a first light scattering APD based on first light intensity information of the light source monitoring unit, second light intensity information of the avalanche photodiode detector and an optimal APD coefficient, and obtaining a second light scattering APD based on first light intensity information of the light source monitoring unit, third light intensity information of the photomultiplier tube detector and an optimal PMT coefficient; Based on a preset signal-to-noise ratio calculation formula, respectively calculating the signal-to-noise ratio of the first light-scattering APD and the signal-to-noise ratio of the second light-scattering APD; Based on the signal-to-noise ratio of the first light-scattering APD, the signal-to-noise ratio of the second light-scattering APD, and a preset signal-to-noise ratio threshold, a light-scattering APD for particle analysis is determined from the first light-scattering APD and the second light-scattering APD.

9. A storage medium, characterized in that: The storage medium stores programs or instructions, and when the programs or instructions are executed by the processor, the steps of the particle analysis method based on particle size spectrum as claimed in claim 8 are implemented.

10. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the program, the steps of the particle analysis method based on particle size spectrum described in claim 8 are implemented.

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