CN113552047A - Particle counter calibration method and particle metering method - Google Patents
Particle counter calibration method and particle metering method Download PDFInfo
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Abstract
The invention provides a particle counter calibration method, which comprises the following steps: the first calibration process, namely calibrating the laser working area of the particle counter; and a second calibration process: enabling particle airflow with a fixed concentration and a predicted particle size to pass through the calibrated laser working area, and calibrating a threshold voltage corresponding to the predicted particle size by adopting a Labview acquisition system with a high-speed ADC (analog to digital converter) board card; an auxiliary calibration process: and calibrating the photoelectric receiving module by adopting a peripheral tool, wherein the peripheral tool comprises a laser for providing uniform laser. The traditional method of calibrating by depending on manual work and a standard particle counter is changed, and the calibration efficiency is high and the precision is good. The particle metering method provided by the invention has corresponding advantages because the particle counter calibrated by the calibration method provided by the invention is implemented; the particle size distribution can be more refined, the particle concentration is improved to a higher level, and the further development of the metering technology is promoted.
Description
Technical Field
The invention belongs to the technical field of metering, and particularly relates to a calibration method for calibrating an optical particle counter and a metering method using the particle counter.
Background
Light scattering laser particle counters are instruments that are typically used to measure the number and size distribution of airborne particles in a single volume in a clean environment. The optical module is used for receiving the detection laser light scattered by dust particles and generating a pulse signal through the photoelectric receiving module, outputting and amplifying the pulse signal, then processing the signal, comparing the signal with a standard particle signal, and expressing a comparison result by using different parameters. The device is widely applied to industries such as medicine, precision machinery and microorganism, and is also one of main metering devices of authorities such as epidemic prevention stations, disease control centers and quality supervision authorities. With the gradual implementation of GMP certification and the analysis of the spread of diseases by particles in aerosol, the application of particle counters is becoming more and more widespread. However, the accuracy, reliability and consistency of the counting measurement of the existing particle counter product cannot completely meet the application requirements, and one of the important reasons is that the existing particle counter is not completely calibrated before being put into use, or the effect of the calibration method does not meet the requirements. The calibration method of the existing particle counter is generally that an inspector blindly adjusts the voltage threshold of each particle channel comparator, so that the particle count of each channel is approximately the same as that of a standard particle counter. Obviously, calibration efficiency is low, accuracy is poor, and consistency among multiple (per) particle counters is difficult to achieve. Therefore, for enterprises producing particle counters, the existing calibration method is not ideal in effect, and cannot be used for effectively calibrating the optical module and the photoelectric receiving module of the particle counter respectively, so that the improvement of the production efficiency of the enterprises and the optimization of the product yield are directly influenced. The corresponding existing particle metering method also has corresponding defects, voltage pulse signals cannot be accurately acquired, and particularly when the particle concentration is high, the measurement result is not ideal, the particle size distribution cannot be refined, and the application requirements cannot be met.
Therefore, at present, it is necessary to research an effective and feasible particle counter calibration method and a corresponding particle metering method, which can be applied to the calibration of a particle counter and the metering work using the particle counter, and improve the accuracy and reliability of the particle counter in use, thereby further promoting the deep development and wide application of the metering technology.
Disclosure of Invention
The present invention is directed to solving some, all, or potential problems of the prior art, and in one aspect, the present invention provides a calibration method for a particle counter, which is used for calibration before the particle counter is put into use. The invention also provides a corresponding particle metering method for testing the particle size and the distribution of airborne dust particles.
Some terms or principles that may be involved in the present invention are explained by way of example and not by way of limitation as follows:
mie scattering (Mie scattering), an optical phenomenon, is one case of scattering. When the size of the particles is close to or larger than the wavelength λ of the incident light, most of the incident light is scattered in the forward and vertical directions, which is called mie scattering.
Particle size (particulate size): the diameter of a certain scattering particle in the air is the diameter of the particle corresponding to the intensity of the scattered light, in mum.
Particle concentration (particle concentration) is the number of discrete particles having a particle diameter not smaller than a predetermined value in a unit volume of air to be measured at a predetermined sampling flow rate and sampling time.
Standard particle counter: and obtaining a satisfactory result through national organization comparison.
The metering principle of the particle counter in the invention is as follows: in an optical field (laser working area) with uniform output of an optical module, light scattered out of a single particle through Mie scattering is collected by a Mie scattering collector through airflow of the particle, then the light irradiates on a photosensitive element of a photoelectric receiving module, energy is converted into a voltage pulse signal through a preamplification circuit, the voltage pulse signal is collected, and the size and the distribution of particle diameters are resolved by an algorithm.
The particle counter calibration method provided by the invention comprises the following steps: the first calibration process, namely calibrating the laser working area of the particle counter; and a second calibration process: enabling particle airflow with a fixed concentration and a predicted particle size to pass through the calibrated laser working area, and calibrating a threshold voltage corresponding to the predicted particle size by adopting a Labview acquisition system with a high-speed ADC (analog to digital converter) board card; an auxiliary calibration process: calibrating a photoelectric receiving module of the particle counter by adopting an external tool, wherein the external tool comprises an external laser for providing uniform laser; wherein the auxiliary calibration process is not time-sequence related to the first calibration process and the second calibration process. That is, the auxiliary calibration process may be performed before the first calibration process, after the second calibration process, or between the first and second calibration processes, or may be performed simultaneously with the first calibration process or the second calibration process, which is not limited. Wherein Labview is system engineering software designed specifically for testing, measurement and control applications, with fast access to hardware and data information.
The photoelectric receiving module of the particle counter comprises a photosensitive element and a preamplification circuit; in the auxiliary calibration process, the uniform laser is used for completely covering and irradiating the photosensitive element, and a universal meter is used for measuring the actual output voltage of the pre-amplification circuit; comparing the actual output voltage with a design theoretical value of the output voltage of the pre-amplification circuit; and if the actual output voltage is not consistent with the design theoretical value, setting a correction coefficient according to the proportion between the actual output voltage and the design theoretical value.
The photoelectric receiving module also comprises an EEPROM (electrically erasable and programmable read only memory); and in the auxiliary calibration process, writing the actual output voltage and the correction coefficient into the EEPROM. The EEPROM is a memory chip with no data loss after power failure, and is generally used for plug and play. After the actual output voltage and the correction coefficient are written into the EEPROM, a main control board of the particle counter is inserted during counting, and the correction coefficient can be read to correct the counting result, so that the counting result is not deviated due to the difference between the actual output voltage of the photoelectric receiving module and the design theoretical value, and the reliability and the accuracy of the counting result are guaranteed.
And the auxiliary calibration process also comprises numbering the photoelectric receiving module, and recording the number of the photoelectric receiving module and the corresponding correction coefficient. And during subsequent counting, according to the number of the photoelectric receiving module of the particle counter used for counting, writing a correction coefficient corresponding to the number into a memory of a corresponding particle counter main control board, and calling the correction coefficient to correct a counting result during counting so as to ensure the accuracy of the counting result. The output voltage of the preamplification circuit of the particle counter is analyzed and calculated to set correction parameters in the auxiliary calibration process, so that the accuracy of the particle counter in the metering work application is improved, the actual output voltage of the preamplification circuit of the particle counter is allowed to be different from the design theoretical value, the flexibility in the manufacturing of the particle counter is facilitated, and the production difficulty is reduced to a certain extent.
In the second calibration process, Labview collects waveforms output by the pre-amplification circuit, the peak value of each waveform is statistically analyzed, and then the threshold voltage of the particles with the preset particle size is marked; and at least sequentially introducing 4 different predicted particle sizes, and distinguishing and marking threshold voltages corresponding to the at least 4 predicted particle sizes.
The optical module of the particle counter comprises a laser and a beam shaping structure; the beam shaping structure comprises a lens; before the first calibration process, shaping an output light beam of the laser to obtain a working light beam; the light beam shaping structure comprises a lens, and the working light beam is a flat-top light beam; in the first calibration process, the light spot of the laser working area is calibrated by adjusting the position of the lens.
And in the first calibration process, collecting light spots of the working light beam, measuring whether the size of the light spots accords with a preset value, and evaluating whether the light spots are light spots with uniform light intensity. The measurement of the size of the light spot and the evaluation of whether the light intensity in the light spot is uniform can be synchronously carried out, or the size of the light spot can be measured firstly, and when the size of the light spot meets a preset value meeting the counting requirement, the evaluation of whether the light intensity in the light spot is uniform is carried out; and if the measured spot size is inconsistent with the preset value, adjusting the distance between the lens and the laser, and adjusting the spot size of the working beam.
In the first calibration process, a first light spot cutting clamp is adopted to cut a first working light spot with a preset area of the working light beam at the starting point of the laser working area, and a power meter is accessed; calculating the total power of the first working light spot, and correspondingly adjusting the power supply of a laser to ensure that the total power of the first working light spot is consistent with a preset standard total power; the average intensity of the first working spot is calculated.
In the first calibration process, a second light spot cutting clamp is further adopted, a second working light spot of the working beam with the preset area is cut at the endpoint of the laser working area, and a power meter is accessed; calculating the average light intensity of the second working light spot.
And if the percentage difference between the average light intensity of the first working light spot and the average light intensity of the second working light spot ranges from-10% to +10%, determining that the first calibration process is finished. I.e. spot adjustment of the working beam is completed.
Another aspect of the present invention provides a particle metering method, including: the particle counter is calibrated by adopting the particle counter calibration method on one hand; and then, collecting a voltage pulse signal output by the preamplifier circuit, and distinguishing the size and the distribution of the particle size.
Collecting the voltage pulse signal by adopting a high-speed analog-to-digital converter; the acquisition speed of the high-speed analog-to-digital converter is more than 10MSPS (Million Samples per Second); inputting the voltage pulse signal into an Application Specific Integrated Circuit (ASIC) to calculate and obtain the size and the distribution of the particle diameter; the application specific integrated circuit device is integrated on a main control board of the particle counter for metering and comprises an FPGA. An FPGA (Field Programmable Gate Array) is a product of further development based on Programmable devices such as PAL and GAL. It appears as a semi-custom circuit in the field of Application Specific Integrated Circuits (ASICs).
The FPGA reads the correction coefficient and operates a resolution algorithm to perform resolution; and the resolution algorithm adopts the correction coefficient to adjust the resolution of the particle size.
Compared with the prior art, the invention has the main beneficial effects that:
1. according to the particle counter calibration method, a Labview acquisition system with a high-speed ADC board card is adopted for calibration, the traditional method of manually and standard particle counter calibration is changed, and the particle size and the corresponding threshold voltage thereof can be calibrated at a higher precision level; the photoelectric receiving module can be calibrated and analyzed through a discrete auxiliary calibration process; the particle counters calibrated by the calibration method of the invention have good consistency among a plurality of particle counters; the method is very beneficial to the further popularization and development of the metering technology, and promotes the improvement of the production efficiency of particle counter production enterprises and the optimization of the product yield.
2. According to the particle metering method, the complete range of the particle size, such as 0.2 mu m, 0.3 mu m, 0.4 mu m and the like, can be effectively distinguished by metering after the particle counter calibrated by the calibration method, the particle size distribution can be more refined, and the particle concentration can be improved to a higher level. In addition, the test efficiency is high, the reliability is good, and the accuracy of the test result can be further improved by reading the correction coefficient.
Drawings
Fig. 1 is a schematic diagram of a particle counter according to a first embodiment of the present invention.
Fig. 2 is a schematic process diagram of a particle counter calibration method according to an embodiment of the invention.
Fig. 3 is a schematic diagram of measuring a first working light spot according to a first embodiment of the present invention.
Fig. 4 is a schematic diagram of measuring a second working light spot according to a first embodiment of the present invention.
Fig. 5 is a schematic diagram of an auxiliary calibration situation according to a first embodiment of the present invention.
Fig. 6 is a schematic view illustrating a particle metering method according to a first embodiment of the invention.
Fig. 7 is a schematic diagram of working beam spot acquisition according to a second embodiment of the present invention.
Detailed Description
The technical solutions in the specific embodiments of the present invention will be clearly and completely described below, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings. In the figures, parts of the same structure or function are denoted by the same reference numerals, and not all parts shown are denoted by the associated reference numerals in all figures for reasons of clarity of presentation.
The operations of the embodiments are depicted in the following embodiments in a particular order, which is provided for better understanding of the details of the embodiments and to provide a thorough understanding of the present invention, but the order is not necessarily one-to-one correspondence with the methods of the present invention, and is not intended to limit the scope of the present invention.
It is to be noted that the flow charts and block diagrams in the figures illustrate the operational procedures which may be implemented by the methods according to the embodiments of the present invention. It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the alternative, depending upon the functionality involved. It is also noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and manual acts.
Example one
In the first embodiment of the present invention, as shown in fig. 1, the particle counter of the first embodiment is composed of an optical module for providing a working beam, a laser working area for detection, and a photoelectric receiving module for receiving and converting an optical signal. Wherein the laser working area is a photosensitive working area and a Mie scattering collector. The optical module is provided with a laser serving as a laser source and a power supply part thereof, and the output light intensity of the laser source can be adjusted by adjusting the power supply of the laser. In this embodiment, the particle counter of the example is provided with a light path shaping structure near the output end of the laser, a gaussian spot of an output beam of the laser is shaped to obtain a working beam, and a spot formed by the working beam in a laser working area is flat-top and uniform. And the light emitted by the single particle after passing through the Mie scattering collector is collected by the photoelectric receiving module to perform photoelectric signal conversion. The photosensitive element of this embodiment is a photodiode, and in some implementations, other photosensitive elements such as a phototransistor are used, without limitation. The particle size calibration equipment adopted in the embodiment is a Labview acquisition system with a high-speed ADC (analog to digital converter) board card. In the counting work of the particle counter, the particle size and distribution results are obtained through ADC (analog-to-digital conversion) and FPGA (field programmable gate array)/ASIC (application specific integrated circuit) operation according to a particle size range algorithm.
In this embodiment, as shown in fig. 2, the method for calibrating a particle counter includes: the first calibration process, namely calibrating the laser working area of the particle counter; and a second calibration process: enabling particle airflow with a fixed concentration and a predicted particle size to pass through a calibrated laser working area, and calibrating a threshold voltage corresponding to the predicted particle size by adopting a Labview acquisition system with a high-speed ADC (analog to digital converter) board card; an auxiliary calibration process: and calibrating the photoelectric receiving module by adopting a peripheral tool, wherein the peripheral tool comprises a peripheral laser for providing uniform laser. The auxiliary calibration process is not time sequence related to the first calibration process and the second calibration process. In the embodiment, the specific operation of the auxiliary calibration process of the example of the invention is performed between the first calibration process and the second calibration process for facilitating understanding of the invention.
In this embodiment, the beam shaping structure of the particle counter shapes the output beam of the laser to obtain a working beam. The beam shaping structure comprises a lens, and the working beam is a flat-top beam. And calibrating the shaped working beam in a first calibration process to enable the working beam to meet the application requirements. Referring to fig. 3 and 4, in the first calibration process, a first light spot cutting fixture is used to cut a first working light spot with a preset area of a working light beam at the starting point of a laser working area, and the first working light spot is accessed to a power meter; calculating the total power of the first working light spot, and correspondingly adjusting the power supply of the laser to ensure that the total power is consistent with the preset standard total power; the average intensity of the first working spot is calculated. Then, a second light spot cutting clamp is adopted to cut a second working light spot with the same preset area as the first working light spot of the working light beam at the end point of the laser working area, and the second working light spot is accessed to a power meter; the average intensity of the second working spot is calculated. In this embodiment, the apertures of the first spot cutting jig and the second spot cutting jig are the same, and the sizes of the spots projected onto the optical power meter are kept consistent, and the average light intensities calculated under the two jigs can determine whether the shaping of the light path is well adjusted, if the deviation is controlled within 10%, that is, the difference percentage range between the average light intensity of the first working spot and the average light intensity of the second working spot is between-10% and +10%, the light path is considered to be well adjusted, otherwise, the spots are not well adjusted and need to be continuously adjusted. The length of the second spot cutting jig is longer than that of the first spot cutting jig, and thus, the second spot cutting jig can be respectively disposed at the start point and the end point of the laser working area. In some implementations, the light spot is captured at multiple positions in the laser working area for testing, and the light spot cutting fixture is not necessarily arranged only at the starting point and the ending point, but is not limited.
In this embodiment, as shown in fig. 5, in the auxiliary calibration process, after the photodiode is completely covered and irradiated by the uniform laser provided by the peripheral laser, the actual output voltage of the current preamplifier circuit is tested by using a multimeter. And comparing the actual output voltage with a designed theoretical value of the output voltage of a pre-amplification circuit of the particle counter, and if the actual output voltage is inconsistent with the designed theoretical value, setting a correction coefficient according to the ratio of the actual output voltage to the designed theoretical value. The design theoretical value of the output voltage can be obtained by calculation. Generally, the uniform laser intensity of the peripheral laser is known, the standard value of the photoelectric conversion rate of the photodiode of the particle counter is provided when the photodiode manufacturer leaves a factory, and the design theoretical value of the output voltage can be calculated according to the gain theory of the preamplifier circuit. For convenience of understanding, for example, it is known that the power of the uniform laser is 0.5 μ W, the photoelectric conversion rate of the photodiode is 0.5A/W, the amplification gain of the preamplifier circuit is 4000000 Ω, the theoretical value of the output voltage is 1V, under the same illumination condition, the actual output voltage of the preamplifier circuit is only 0.9V, the correction coefficient of the particle counter is 1/0.9=0.9, and the EEPROM records the actual output voltage 0.9V and the correction coefficient 0.9 (or records 90% in percentage).
In the embodiment, the photoelectric receiving module is further provided with an EEPROM, and the actual output voltage obtained by measurement and the corresponding correction coefficient are written into the EEPROM in the auxiliary calibration process. When the particle counter is used for counting, the EEPROM is plugged into the main control board, the FPGA can read the correction coefficient in the EEPROM, and the resolution algorithm adopts the correction coefficient to adjust the resolution of the particle size.
In this embodiment, in the second calibration process, the waveform output by the preamplifier circuit is collected through particles with a predicted particle size in the laser working region, the peak value of the waveform is statistically analyzed, and the threshold voltage corresponding to the predicted particle size is marked. Example practices include: and collecting waveforms output by a pre-amplification circuit through 0.3 mu m particles by using Labview, statistically analyzing the peak value of each waveform, and marking the threshold voltage of the 0.3 mu m particles. Similarly, through 0.5μm particles, collecting waveforms output by a pre-amplification circuit by using Labview, statistically analyzing the peak value of each waveform, and marking the threshold voltage of the 0.5μm particles; through 1.0 mu m particles, collecting waveforms output by a pre-amplification circuit by using Labview, carrying out statistical analysis on the peak value of each waveform, and then marking the threshold voltage of the 1.0 mu m particles. Similar operations were also performed with 3 other particle streams of different predetermined particle sizes. And calibrating the particles with different particle sizes correspondingly according to the number of the particle size channels of the particle counter. The number of the particle size channels and the number of the types of different particle sizes to be calibrated can be set according to the actual application requirements, and are not limited.
The acquisition speed of the high-speed analog-to-digital converter of the embodiment is above 10MSPS (Million Samples per Second), and the ADC adopted in the example is an AD9629 type analog-to-digital converter of ADI (adno semiconductor technology limited).
As shown in fig. 6, the particle metering method of the present embodiment is to calibrate the particle counter according to the calibration method of the particle counter of the present embodiment; collecting a voltage pulse signal by adopting a high-speed analog-to-digital converter; and distinguishing the particle size corresponding to the acquired waveform according to the threshold voltage calculated by Labview during calibration. And inputting the voltage pulse signal into the FPGA, and calculating to obtain the particle size and distribution. By adopting the method, the complete range of the particle size can be distinguished, such as 0.2 mu m, 0.3 mu m, 0.4 mu m and the like, the particle size distribution can be even more refined, and the particle concentration can be improved to a higher level which is more than 100 times that of a common comparator. The ADC has high requirements, the particle size can be completely distributed only when the acquisition speed reaches more than 10M, and the general control part can adopt an FPGA or other special control chips without limitation.
Example two
As shown in fig. 7, the difference between the second embodiment and the first embodiment is mainly that in the first calibration process, the light spot of the working beam is collected and evaluated. The laser spot collector is adopted, specifically a CCD camera which is arranged on the slide rail and can be adjusted in front and back positions is used for obtaining a plurality of spot information of the working light beam, whether the spot size meets the requirement or not is statistically analyzed according to the obtained plurality of spot information of the working light beam, and whether the light intensity distribution in the spot is uniform or not is judged. And if the size of the light spot is not consistent with the preset value, adjusting the light beam shaping structure, and generally adjusting the distance between the lens and the laser, and acquiring light spot information for evaluation after adjustment until the size of the light spot is consistent with the preset value. In this embodiment, a relatively convenient CCD camera is used for acquisition, and certainly, in other embodiments, the laser spot acquisition unit may also use a small bin APD or PIN detector to build a three-dimensional scanning detection device, which is not specifically limited in the present invention.
In this embodiment, another difference from the first embodiment is that in the auxiliary calibration process, no EEPROM is provided, but an external recording mode is adopted to number, record the number and the corresponding correction coefficient for each photo-electric receiving module, in the example, a label is attached to the surface of the photo-electric receiving module of the particle counter, and the number and the correction coefficient are identified on the label. And when the particle counter is used for counting subsequently, the correction coefficient is written into a memory of the main control board for being called by the FPGA.
For clarity of description, the use of certain conventional and specific terms and phrases is intended to be illustrative and not restrictive, but rather to limit the scope of the invention to the particular letter and translation thereof.
It is further noted that, herein, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
The present invention has been described in detail, and the structure and operation principle of the present invention are explained by applying specific embodiments, and the above description of the embodiments is only used to help understanding the method and core idea of the present invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
Claims (7)
1. The particle counter calibration method is characterized by comprising the following steps: the method comprises the following steps:
a first calibration process: calibrating a laser working area of the particle counter;
and a second calibration process: enabling particle airflow with a fixed concentration and a predicted particle size to pass through the calibrated laser working area, and calibrating a threshold voltage corresponding to the predicted particle size by adopting a Labview acquisition system with a high-speed ADC (analog to digital converter) board card;
an auxiliary calibration process: calibrating a photoelectric receiving module of the particle counter by adopting an external tool, wherein the external tool comprises an external laser for providing uniform laser; wherein the auxiliary calibration process is not time-sequence related to the first calibration process and the second calibration process.
2. The method for calibrating a particle counter according to claim 1, wherein: the photoelectric receiving module of the particle counter comprises a photosensitive element and a preamplification circuit;
in the auxiliary calibration process, the uniform laser is used for completely covering and irradiating the photosensitive element, and a universal meter is used for measuring the actual output voltage of the pre-amplification circuit;
comparing the actual output voltage with a design theoretical value of the output voltage of the pre-amplification circuit; and if the actual output voltage is not consistent with the design theoretical value, setting a correction coefficient according to the proportion between the actual output voltage and the design theoretical value.
3. The method for calibrating a particle counter according to claim 2, wherein: in the second calibration process, Labview collects waveforms output by the pre-amplification circuit, the peak value of each waveform is statistically analyzed, and then the threshold voltage of the particles with the preset particle size is marked; and at least sequentially introducing 4 different predicted particle sizes, and distinguishing and marking threshold voltages corresponding to the at least 4 predicted particle sizes.
4. A method for calibrating a particle counter according to any of claims 1-3, wherein: the optical module of the particle counter comprises a laser and a beam shaping structure; the beam shaping structure comprises a lens; before the first calibration process, shaping an output light beam of the laser to obtain a working light beam; the working light beam is a flat-top light beam; in the first calibration process, the light spot of the laser working area is calibrated by adjusting the position of the lens.
5. A particle metering method, characterized by: the method comprises the following steps: calibrating the particle counter by the calibration method of any one of claims 1 to 4; and then, collecting a voltage pulse signal output by the preamplifier circuit, and distinguishing the size and the distribution of the particle size.
6. The particle metering method according to claim 5, wherein: collecting the voltage pulse signal by adopting a high-speed analog-to-digital converter; the acquisition speed of the high-speed analog-to-digital converter is above 10 MSPS; inputting the voltage pulse signal into a special integrated circuit to calculate and obtain the size and the distribution of the particle size; the application specific integrated circuit device is integrated on a main control board of the particle counter for metering and comprises an FPGA.
7. The particle metering method according to claim 6, wherein: the FPGA reads the correction coefficient and operates a resolution algorithm to perform resolution; and the resolution algorithm adopts the correction coefficient to adjust the resolution of the particle size.
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