A multi-path particle counter and method of operation thereof

Abstract

The application provides a multi-light-path particle counter and a working method thereof, comprising an air path system, an optical system, a detection cavity and a signal acquisition and processing system; the air path system is arranged in a first direction of the detection cavity, the optical system is arranged in a second direction of the detection cavity, and the signal acquisition and processing system is arranged in a third direction of the detection cavity; the air path system comprises an air inlet module and an air outlet module arranged in the first direction of the detection cavity, and is used for enabling particles in a to-be-detected air flow to move linearly in the detection cavity; the optical system comprises a plurality of lasers and corresponding optical traps; the signal acquisition and processing system is used for acquiring scattered light of different sides of the particles generated based on different lasers, and converting optical pulse signals into electrical pulse signals; cumulative counting of the particles is realized based on the number of the acquired electrical pulse signals, the particle size of the particles is obtained based on the amplitude of the electrical pulse, and the number of different types of particles is determined based on the particle size.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of optical detection, and particularly relates to a multi-light-path particle counter and a working method thereof. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] The dust particle counter is based on the single-particle Mie light scattering principle (Mie scattering), and can monitor the particle size, type and particle number per cubic meter of particulate matter in real time, and can be applied to electronic product production, pharmaceutical production, semiconductor production, clean laboratories and medical health and other clean scenes.

[0004] The principle of the particle counter on the market at present is that the particles to be measured enter the detection cavity, the particles are scattered under the irradiation of a laser beam, and the scattered signal is converted into an electrical signal by a detector. The inventor finds that for the traditional particle counter, a single-light-path laser beam is irradiated onto a certain face of the particle to obtain a particle size detection result. For particles with uniform shape, the detection error is small, but when the particle shape is not uniform, the detection error is large. SUMMARY

[0005] The embodiments of the present application provide a multi-light-path particle counter and a working method thereof, to solve the problem that in the prior art, when the particle shape is not uniform, the particle size error obtained by single-light-path laser beam detection is large, thereby leading to inaccurate counting.

[0006] According to a first aspect of the embodiments of the present application, a multi-light-path particle counter is provided, comprising an air path system, an optical system, a detection cavity and a signal acquisition and processing system;

[0007] The air path system is arranged in a first direction of the detection cavity, the optical system is arranged in a second direction of the detection cavity, and the signal acquisition and processing system is located in a third direction of the detection cavity, wherein the first direction, the second direction and the third direction are perpendicular to each other;

[0008] The air path system comprises an air inlet module and an air outlet module arranged in the first direction of the detection cavity, for making the particles in the air flow to be measured move linearly in the detection cavity;

[0009] The optical system comprises a plurality of lasers and corresponding optical traps, wherein each laser is arranged in the detection cavity, and each laser is spaced apart from each other by a preset distance, so as to generate laser beams irradiated on different sides of the particles;

[0010] The signal acquisition and processing system is used for acquiring scattered light of different sides of the particle generated by different lasers, and converting the light pulse signal into an electric pulse signal; realizing cumulative counting of the particle based on the number of the acquired electric pulse signals, obtaining the particle size based on the amplitude of the electric pulse, and determining the number of different types of particles based on the particle size.

[0011] Further, the signal acquisition and processing system comprises a plurality of light detectors corresponding to different lasers respectively, and used for acquiring scattered light of different sides of the particle generated by different lasers.

[0012] Further, for each particle entering the detection cavity, a plurality of particle size estimation values are obtained based on the amplitudes of different electric pulses corresponding to the particle obtained by the plurality of light detectors, and the particle size of the to-be-measured particle is determined based on the standard deviation, the relative range and the preset threshold of the plurality of particle size estimation values.

[0013] Further, the particle size of the to-be-measured particle is determined based on the standard deviation, the relative range and the preset threshold of the plurality of particle size estimation values, specifically:

[0014] When the standard deviation is less than a preset first threshold and the relative range is less than a second threshold, the particle size is obtained by the following formula:

[0015]

[0016] When the standard deviation is less than a preset first threshold and the relative range is not less than a second threshold, the particle size is obtained by the following formula:

[0017]

[0018] When the standard deviation is not less than a preset first threshold, the current particle is ignored;

[0019] Wherein, D1 to Dn represent a plurality of particle size estimation values, Dmean represents the mean value of the particle size estimation values, Dmax is the maximum value of the plurality of particle size estimation values, and Dmin is the minimum value of the plurality of particle size estimation values.

[0020] Further, the number of different types of particles is determined based on the particle size, specifically: the number of particles of the same size is calculated based on the cumulative number of all particles and the particle size of each particle, and the number of different types of particles is counted.

[0021] Further, the cumulative counting of the particle is realized based on the number of the acquired electric pulse signals, specifically: the cumulative counting of the particle is obtained based on the number of the electric pulse signals converted from the scattered light of a side of the particle generated by any laser.

[0022] Further, the optical trap is arranged in the detection cavity and at a position opposite to the corresponding laser.

[0023] Further, the air inlet module comprises an air inlet nozzle and a high-pressure nozzle connected in sequence; the air outlet module comprises an air outlet nozzle, an air pump connected with the air outlet nozzle, and a flow meter located in a connecting pipeline between the air outlet nozzle and the air pump.

[0024] Further, the detection cavity adopts a spherical structure.

[0025] According to a second aspect of the embodiment of the present application, a working method of a multi-optical-path particle counter is provided, comprising:

[0026] The laser generated by the plurality of lasers is shaped by the optical lens to form laser light knives in different directions, which converge at the detection cavity to form a photosensitive area;

[0027] The particles in the sampling airflow enter the photosensitive area in the detection cavity through the high-pressure nozzle, and the particles cut the laser light knives in different directions to generate scattered light with different signal strengths, forming a plurality of light pulse signals;

[0028] The scattered light pulse signals on different sides of the particles generated based on different lasers are collected, and the light pulse signals are converted into electric pulse signals;

[0029] The cumulative counting of the particles is realized based on the number of the collected electric pulse signals, the particle size is obtained based on the amplitude of the electric pulse, and the number of different types of particles is determined based on the particle size.

[0030] The above one or more technical solutions have the following beneficial effects:

[0031] (1) The present application provides a working method of a multi-optical-path particle counter, which can obtain the most accurate particle size of the particles based on a preset strategy through simultaneous detection of the particles at different angles, and then accurately count different particles by combining the obtained particle size;

[0032] (2) The present application adopts a spherical detection cavity, and a plurality of lasers, optical traps and photodetectors are arranged on the surface of the detection cavity, so that the scattered light on different sides of the particles to be detected can be obtained, a plurality of particle size estimates can be obtained based on the scattered light on different sides, and the particle size can be accurately identified based on the plurality of particle size estimates, thereby laying a foundation for accurate counting of different types of particles.

[0033] The advantages of the additional aspects of the present application will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application, and are incorporated by reference in their entirety. The embodiments of the present application, together with its advantages, can be understood by a study of the following detailed description, taken in conjunction with the drawings.

[0035] Figure 1 A cross-sectional view of a multi-path particle counter in XOY configuration as described in the background of the present application;

[0036] Figure 2 A cross-sectional view of a multi-path particle counter in XOZ configuration as described in the background of the present application;

[0037] Figure 3 A cross-sectional view of a multi-path particle counter in YOZ configuration as described in the background of the present application;

[0038] Wherein, 1, gas inlet nozzle; 2, high pressure nozzle; 3, particle to be measured; 4, gas outlet nozzle; 5, flow meter; 6, air pump; 7, detection cavity; 8, laser; 9, light trap; 10, concave mirror; 11, photodetector. DETAILED DESCRIPTION

[0039] It should be noted that the following detailed description is merely exemplary and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0040] It should be noted that the terms used herein are merely for the purpose of describing specific embodiments and are not intended to limit exemplary embodiments according to the present application.

[0041] In the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0042] The purpose of the present embodiment is to provide a multi-path particle counter, comprising a gas path system, an optical system, a detection cavity and a signal acquisition and processing system;

[0043] The gas path system is arranged in the first direction of the detection cavity, the optical system is arranged in the second direction of the detection cavity, and the signal acquisition and processing system is located in the third direction of the detection cavity, wherein the first direction, the second direction and the third direction are perpendicular to each other;

[0044] The gas path system comprises an air inlet module and an air outlet module arranged in the first direction of the detection cavity, for making the particles in the gas flow to be measured move linearly in the detection cavity;

[0045] The optical system comprises a plurality of lasers and corresponding light traps, wherein each laser is arranged in the detection cavity, and each laser is spaced apart by a preset distance to generate laser beams irradiating different sides of the particle.

[0046] The signal acquisition and processing system is used for acquiring scattered light of different sides of the particle generated based on different lasers, and converting the light pulse signal into an electric pulse signal; cumulative counting of the particle is realized based on the number of the acquired electric pulse signals, the particle size is obtained based on the amplitude of the electric pulse, and the number of different types of particles is determined based on the particle size.

[0047] Specifically, as shown in Figure 1 , an XOY cross-sectional view of the counter structure of the embodiment is shown; Figure 2 , an XOZ cross-sectional view is shown, Figure 3 , and a YOZ cross-sectional view is shown.

[0048] For ease of understanding, a space rectangular coordinate system is constructed for description, and the X, Y and Z axes of the detection cavity 7 are respectively provided with a gas path system, a signal acquisition system and an optical system, and the gas path system, the signal acquisition system and the optical system are perpendicular to each other.

[0049] Preferably, the detection cavity is a spherical structure.

[0050] In specific implementation, the gas inlet module of the gas path system comprises a gas inlet nozzle 1 and a high-pressure nozzle 2 connected in sequence; the gas outlet module of the gas path system comprises a gas outlet nozzle 4, a gas pump 6 connected with the gas outlet nozzle 4, and a flow meter 5 located in the connecting pipeline between the gas outlet nozzle and the gas pump; the gas outlet nozzle 4, the flow meter 5 and the gas pump 6 are connected in sequence by pipelines, the flow meter is used for observing the flow of the gas path system, and the gas pump 6 controls the amount of air extraction by adjusting the pressure.

[0051] Preferably, the gas inlet nozzle is a slot structure, and the slot cross section is parallel to the light-sensitive area.

[0052] Further, the optical system comprises a plurality of lasers 8 (as shown in Figure 2 , three lasers are arranged in the embodiment, and it can be understood that the number can be set according to actual needs in specific implementation) and light traps 9 (as shown in Figure 1As shown, the embodiment is provided with 3, which can be understood that in the specific implementation can be set according to actual demand), the plurality of lasers are arranged on the detection cavity, and the laser beams generated by the plurality of lasers are shaped by the optical lens and then irradiated on different sides of the particles to generate scattered light signals in different directions. Among them, the laser selects a laser with different wavelengths, the optical lens is installed at the front end of the laser, and the optical lens is a aspheric mirror and a cylindrical mirror, and the plurality of optical traps are distributed on the detection cavity and correspond to the lasers for light extinction and stray light collection.

[0053] The signal acquisition system includes a plurality of photodetectors 11 (such as Figure 1 As shown, the embodiment is provided with 3, which can be understood that in the specific implementation can be set according to actual demand), the plurality of lasers are arranged on the detection cavity, and the laser beams generated by the plurality of lasers are shaped by the optical lens and then irradiated on different sides of the particles to generate scattered light signals in different directions. Among them, the laser selects a laser with different wavelengths, the optical lens is installed at the front end of the laser, and the optical lens is a aspheric mirror and a cylindrical mirror, and the plurality of optical traps are distributed on the detection cavity and correspond to the lasers for light extinction and stray light collection.

[0054] In the specific implementation, the detection cavity is provided with a concave mirror for converging the scattered light.

[0055] In the specific implementation, the signal acquisition and processing system includes a plurality of light detectors, and the light detectors correspond to different lasers respectively for obtaining the scattered light of different sides of the particles generated by the different lasers.

[0056] In the specific implementation, for each particle entering the detection cavity, a plurality of particle size estimation values are obtained based on the amplitudes of different electric pulses corresponding to the particles obtained by the plurality of light detectors, and the particle size of the to-be-measured particle is determined based on the standard deviation, the relative range and the preset threshold of the plurality of particle size estimation values.

[0057] In the specific implementation, the particle size of the to-be-measured particle is determined based on the standard deviation, the relative range and the preset threshold of the plurality of particle size estimation values, and specifically:

[0058] When the standard deviation is less than a preset first threshold and the relative range is less than a second threshold, the particle size is obtained through the following formula:

[0059]

[0060] When the standard deviation is less than a preset first threshold and the relative range is less than a second threshold, the particle size is obtained through the following formula:

[0061]

[0062] When the standard deviation is not less than the preset first threshold value, the current particle is ignored;

[0063] Dmax - Dmin < Dmean < Dmax + Dmin wherein D1 to Dn represent a plurality of particle size estimates, Dmean represents a mean of the particle size estimates, Dmax is a maximum of the plurality of particle size estimates, and Dmin is a minimum of the plurality of particle size estimates.

[0064] In a specific implementation, the number of different types of particles is determined based on the particle size, specifically, the number of particles of the same size is calculated based on the cumulative number of all particles obtained and the particle size of each particle, and the number of different types of particles is counted.

[0065] In a specific implementation, the cumulative count of particles is achieved based on the number of electrical pulse signals, specifically, the cumulative count of particles is obtained based on the number of electrical pulse signals converted from the scattered light on one side of the particles generated by any laser.

[0066] In one or more embodiments, a working method of a multi-optical-path particle counter is proposed, corresponding to the multi-optical-path particle counter described above, comprising:

[0067] The laser generated by the plurality of lasers is shaped by the optical lens to form laser light knives in different directions, which converge at the detection cavity to form a photosensitive area;

[0068] The particles in the sampling airflow enter the photosensitive area in the detection cavity through the high-pressure nozzle, and the particles cut the laser light knives in different directions to generate scattered light with different signal strengths, forming a plurality of light pulse signals;

[0069] The scattered light pulse signals on different sides of the particles generated by different lasers are collected, and the light pulse signals are converted into electrical pulse signals;

[0070] The cumulative count of particles is achieved based on the number of electrical pulse signals, the particle size is obtained based on the amplitude of the electrical pulse, and the number of different types of particles is determined based on the particle size.

[0071] Specifically, the working process of the counter is described in detail in combination with specific examples as follows:

[0072] After the air pump is started, the air in the environment is extracted as the sampling airflow, and the suspended particles to be measured follow the sampling airflow to enter the detection cavity through the air inlet and the air inlet nozzle;

[0073] The laser generated by the plurality of lasers is shaped by the optical lens to form laser light knives in different directions, which converge at the detection cavity to form a photosensitive area;

[0074] The particle to be tested 3 enters the photosensitive area in the detection cavity through a high-pressure nozzle. The particle cuts the laser blades in different directions, generating scattered light with different signal intensities, forming multiple light pulse signals.

[0075] Multiple optical pulse signals are received by corresponding photodetectors and converted into electrical pulse signals. After filtering, the number of electrical pulses corresponds to the number of particles, and the amplitude of the electrical pulses corresponds to the relative size of the particles.

[0076] Standard particles were generated using a standard aerosol particle generator. The orifice size of the generator could be selected from 1μm, 2.5μm, 10μm, 20μm, 30μm, and 100μm. Different concentrations of standard particles were generated using DOP solution (dioctyl phthalate). The relationship between standard particles of different sizes and the amplitude of the electrical pulse signal was plotted as a calibration curve. The amplitudes of different electrical pulses on the test particles were compared with the calibration curve to obtain multiple detection particle sizes for a single test particle. After removing outliers, the multiple particle sizes were denoted as D1, D2, D3, ..., Dn.

[0077] Accurate methods for determining the particle size of multiple microparticles:

[0078] The measured particle sizes were statistically analyzed to obtain the maximum value D. max Minimum value D min Average value D mean Calculate the standard deviation (SD) and relative range.

[0079]

[0080] When SD is less than the threshold a When the value is less than the threshold b, it indicates that the data set has a small deviation and the particles are uniformly shaped, approximately spherical. In this case, the particle size D of the measured particle is the mean of all detected particle sizes.

[0081]

[0082] When SD is less than the threshold a When the value is greater than the threshold b, it indicates that the deviation of this data set is small, the particle shape is relatively uniform, and there may be a small number of protruding edges and corners. At this time, the particle size D of the particle being tested is the value excluding the maximum value D. kax Minimum value D min Mean of other values:

[0083]

[0084] When SD is greater than the threshold a, it indicates that the data set has a large deviation and the particle shape is irregular. In this case, the particle size D of the particle to be tested is recorded as invalid.

[0085] wherein D1 to Dn represent a plurality of particle size estimates, Dmean represents a mean of the plurality of particle size estimates, Dmax is a maximum of the plurality of particle size estimates, and Dmin is a minimum of the plurality of particle size estimates.

[0086] Based on the obtained cumulative number of all particles and the particle size of each particle, the number of particles of the same particle size is calculated, and the number of different types of particles is counted.

[0087] The above only describes the preferred embodiments of the present disclosure and is not intended to limit the present disclosure. Those skilled in the art can make various modifications and changes to the present disclosure. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A multi-path particle counter, characterized by, The gas path system, the optical system, the detection cavity, and the signal acquisition and processing system are provided. The gas path system is arranged in a first direction of the detection cavity, the optical system is arranged in a second direction of the detection cavity, and the signal acquisition and processing system is arranged in a third direction of the detection cavity. The gas path system comprises an air inlet module and an air outlet module arranged in the first direction of the detection cavity, and is used for enabling the particles in the to-be-detected airflow to move linearly in the detection cavity. The optical system comprises a plurality of lasers and corresponding optical traps, wherein each laser is arranged in the detection cavity, and the lasers are spaced apart by a preset distance to generate laser beams irradiating different sides of the particles. The signal acquisition and processing system is used for acquiring scattered light of different sides of the particles generated by different lasers, converting the optical pulse signals into electrical pulse signals, counting the particles based on the number of the acquired electrical pulse signals, obtaining the particle size based on the amplitude of the electrical pulse, and determining the number of different types of particles based on the particle size. The signal acquisition and processing system comprises a plurality of optical detectors corresponding to different lasers, and is used for acquiring scattered light of different sides of the particles generated by different lasers. For each particle entering the detection cavity, a plurality of particle size estimation values are obtained based on the amplitudes of different electrical pulses corresponding to the particles obtained by the optical detectors, and the particle size of the to-be-detected particle is determined based on the standard deviation, the relative range, and the preset threshold of the plurality of particle size estimation values.

2. A multi-path particle counter as claimed in claim 1, wherein, The particle size of the to-be-detected particle is determined based on the standard deviation, the relative range, and the preset threshold of the plurality of particle size estimation values, and specifically: When the standard deviation is less than a preset first threshold and the relative range is less than a second threshold, the particle size is obtained by the following formula: When the standard deviation is less than a preset first threshold and the relative range is not less than a second threshold, the particle size is obtained by the following formula: When the standard deviation is not less than a preset first threshold, the current particle is ignored. Wherein, D1 to Dn represent a plurality of particle size estimation values, Dmean represents the mean value of the particle size estimation values, Dmax is the maximum value of the plurality of particle size estimation values, and Dmin is the minimum value of the plurality of particle size estimation values.

3. A multiple light path particle counter as claimed in claim 1, wherein, The number of different types of particles is determined based on the obtained cumulative number of all particles and the particle size of each particle, the number of particles of the same size is calculated, and the number of different types of particles is counted.

4. A multiple light path particle counter as claimed in claim 1, wherein, The cumulative count of the particles is realized based on the number of the electrical pulse signals converted from the scattered light of a side of the particles generated by any laser.

5. A multiple light path particle counter as claimed in claim 1, wherein, The optical traps are arranged in the detection cavity and at the relative positions of the corresponding lasers.

6. A multiple light path particle counter as claimed in claim 1, wherein, The air inlet module comprises an air inlet nozzle and a high-pressure nozzle connected in sequence; the air outlet module comprises an air outlet nozzle, an air pump connected with the air outlet nozzle, and a flow meter located in a pipeline connecting the air outlet nozzle and the air pump.

7. A multiple light path particle counter as claimed in claim 1, wherein, The detection cavity adopts a spherical structure.

8. A method of operating a multi-path particle counter, characterized by, The detection cavity adopts a spherical structure. The laser generated by several lasers is shaped by optical lenses to form laser light knives in different directions, which converge at the bifurcation of the detection cavity to form a photosensitive area; The particles in the sampled airflow enter the photosensitive area in the detection cavity through the high-pressure nozzle, cut the laser light knives in different directions, generate scattered light with different signal strengths, and form several light pulse signals; The scattered light pulse signals on different sides of the particles generated by different lasers are collected, and the light pulse signals are converted into electrical pulse signals; The cumulative counting of the particles is realized based on the number of the collected electrical pulse signals, the particle size is obtained based on the amplitude of the electrical pulse, and the number of different types of particles is determined based on the particle size; The signal acquisition and processing system includes several optical detectors, which correspond to different lasers respectively, and are used to obtain the scattered light on different sides of the particles generated by different lasers; For each particle entering the detection cavity, several particle size estimation values are obtained based on the amplitudes of the different electrical pulses corresponding to the particles obtained by the several optical detectors, and the particle size of the to-be-measured particle is determined based on the standard deviation, the relative range, and the preset threshold of the several particle size estimation values.

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