CN113552046B - Particle counter calibration method and working method - Google Patents
Particle counter calibration method and working methodInfo
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- CN113552046B CN113552046B CN202110843845.7A CN202110843845A CN113552046B CN 113552046 B CN113552046 B CN 113552046B CN 202110843845 A CN202110843845 A CN 202110843845A CN 113552046 B CN113552046 B CN 113552046B
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Abstract
The invention provides a method for calibrating a particle counter, which comprises the steps of calibrating an optical module and calibrating an photoelectric receiving module; calibrating the optical module includes: one-time calibration, namely projecting the light output by the optical module onto a laser spot collector, and judging whether the presented light spots meet the requirements; and (3) performing secondary calibration on the optical module meeting the requirements, accessing an optical power meter, calculating the total power output by the laser, and enabling the total power output by the laser to be consistent with the standard power by adjusting a power supply for supplying power to the laser. Through the calibration of the optical module and the photoelectric receiving module, the counting accuracy and precision of the particle counter can be improved, and the consistency of products is ensured. The invention also provides a working method of the particle counter, which has high product consistency and avoids different classification and counting results of different particle counters on the same beam of particle air flow.
Description
Technical Field
The invention belongs to the technical field of particle counters, and particularly relates to a calibration method and a working method of a particle counter.
Background
The particle counter is an instrument for measuring the number of dust particles and the particle size distribution in a unit volume in a clean environment, is widely applied to authorities such as various drug checkpoints, blood centers, epidemic prevention stations, disease control centers, quality supervision centers and the like, and productive enterprises and scientific research departments such as electronic industry, pharmaceutical workshops, semiconductors, optical or precise machining, plastics, paint spraying, environmental protection, inspection stations and the like, and is mainly used for detecting the air cleanliness in production links or experimental environments, thereby reducing the problem of particulate pollution in production and experimental processes.
The working principle of the particle counter is that based on the Mie scattering principle, the airflow of particles passes through a uniform light field output by an optical module, light of single particles scattered by Mie is collected by an optical collector and then is sent to a photodiode of a photoelectric receiving module, energy is converted into a voltage pulse signal through a pre-amplifying circuit, and the voltage pulse signal is compared with voltages of channels with different particle diameters to distinguish the particle diameters of the particles.
However, the accuracy of particle size identification and quantity of existing particle counter product counts has not been fully satisfactory for application. One of the important reasons is that the particle counter is not calibrated before being put into use or that the calibration effect is not expected.
At present, the calibration method commonly used in the industry is to manually compare the particle counter after the production is completed, and the difference between the particle counter to be calibrated and the particle counter to be calibrated in different particle diameters is not very large as the final calibration result. The calibration method has obvious defects, if the light source of the particle counter has defects, namely the particle counter is defective, the counting of the particle counter is directly regulated by manpower in the later period, the difficulty of manual regulation is increased, the operation process is long, the labor cost is high, and the calibration result is inaccurate.
Therefore, how to ensure the accuracy of particle size calibration of the particle counter, the counting accuracy of the particle number, and how to reduce the calibration complexity and labor cost is an important problem to be solved in the industry.
Disclosure of Invention
The invention provides a calibration method of a particle counter, which can improve the accuracy and precision of the particle counter for classifying particles and ensure the accuracy of different particle counters for classifying and counting particles with the same particle size.
The invention provides a working method of a particle counter, which can improve the accuracy of particle classification and has good product consistency.
Other objects and advantages of the present invention will be further appreciated from the technical features disclosed in the present invention.
To achieve one or a part or all of the above or other objects, a method for calibrating a particle counter according to an embodiment of the present invention includes the following steps: calibrating an optical module, wherein the optical module comprises a laser and a power supply for supplying power to the laser; and calibrating the photoelectric receiving module, wherein the photoelectric receiving module comprises a photodiode and a pre-amplifying circuit which are electrically connected.
Wherein, the calibrating the optical module includes: step 1.1: performing primary calibration on the optical module, including projecting light output by the optical module onto a laser spot collector, and judging whether spots presented on the laser spot collector meet requirements or not; step 1.2: the optical module meeting the requirements is subjected to secondary calibration, which comprises the steps of accessing an optical power meter, calculating the total power output by the laser, and enabling the total power output by the laser to be consistent with the standard power by adjusting a power supply for supplying power to the laser. The technical scheme has the beneficial effects that the optical module with poor light source is removed through primary calibration of the optical module, then the output light power of the optical module is adjusted through secondary calibration, the consistency of products is maintained, a high-quality light source with good consistency and uniform light field distribution is provided, and the counting accuracy and precision of the particle counter are improved.
Whether the light spot in the step 1.1 meets the requirements or not comprises the following steps: whether the size of the light spot meets the requirement or not, and whether the light intensity of the light spot is uniformly distributed or not. The technical scheme has the beneficial effects that the spot size and the light intensity distribution condition of the light source are checked in one-time calibration, defective products are removed rapidly, and the efficiency of the subsequent secondary calibration is improved.
The optical module further comprises an optical path shaping unit, and light emitted by the laser is shaped by the optical path shaping unit and then output. The technical scheme has the beneficial effects that the light energy emitted after shaping is uniform in distribution and less in stray light, and the optical quality of the light output by the optical module is improved.
The calibrating of the photoelectric receiving module comprises the following steps: step 2.1: providing a laser light source, so that the illumination of the laser light source completely covers and irradiates the photodiode; step 2.2: and measuring the output voltage of the pre-amplifying circuit, and regulating the output voltage of the pre-amplifying circuit to be consistent with the standard voltage through a potentiometer. The technical scheme has the beneficial effects that the consistency of the photoelectric receiving module is ensured through the calibration of the photoelectric receiving module, and the counting precision of the particle counter is improved.
The laser source in the step 2.1 is preferably a flat-top beam.
To achieve one or a part of or all of the above or other objects, a method for operating a particle counter according to an embodiment of the present invention includes the following steps: calibrating an optical module or/and a photoelectric receiving module of the particle counter by the calibrating method; marking threshold voltages of particles with different particle diameters of the particle counter; and introducing particle airflow to be detected into the optical field output by the optical module, and comparing and distinguishing the particle numbers of each particle size through output voltage. The technical scheme has the beneficial effects that the product consistency of the particle counter is improved due to the calibration of the optical module and/or the photoelectric receiving module, the difference of the classification counting results of different particle counters on the same beam of particle air flow is avoided, and the accuracy and precision of the particle counter are ensured.
The second step adopts a potentiometer method for marking, and comprises the following steps: the particle generator emits particles with a certain particle size and a fixed concentration; counting the particles with the fixed concentration by a standard particle counter to obtain a standard particle number; and passing the particles with the fixed concentration through a particle counter to be marked, and adjusting the threshold voltage of the particle counter to be marked through a potentiometer, so that the deviation between the particle count value of the particle counter to be marked and the standard particle number is +/-20% under the condition of the same flow. The technical scheme has the beneficial effects that the threshold voltage of the particle counter is marked by the potentiometer, so that the operation is convenient, and the difficulty is low.
Compared with the prior art, the invention has the beneficial effects that:
1. Through the primary calibration and the secondary calibration of the optical module, a high-quality light source with good consistency and uniform light field distribution can be provided, the counting accuracy and precision of the particle counter are improved, and the consistency of products is ensured.
2. By calibrating the photoelectric receiving module, the same threshold voltage of preamplifying circuits of different particle counters to particles with the same particle size is ensured, so that the counting precision of the particle counters is improved.
3. Because of the calibration of the optical module or/and the photoelectric receiving module, the product consistency of the particle counter is improved, the difference of the classification counting results of different particle counters on the same beam of particle airflow is avoided, and the accuracy and precision of the particle counter are ensured.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments, as illustrated in the accompanying drawings.
Drawings
Fig. 1 is a schematic diagram of a calibration method of an optical module according to a first embodiment of the invention.
Fig. 2 is a schematic diagram of a calibration method of an optoelectronic receiving module according to a first embodiment of the present invention.
Fig. 3 is a schematic diagram of a particle counter according to a second embodiment of the invention.
Fig. 4 is a schematic diagram illustrating a working method of a particle counter according to a second embodiment of the invention.
Fig. 5 is a schematic diagram of a particle counter marking threshold voltage according to a second embodiment of the present invention.
Detailed Description
The foregoing and other features, aspects, and advantages of the present invention will become more apparent from the following detailed description of a preferred embodiment, which proceeds with reference to the accompanying drawings. The directional terms mentioned in the following embodiments are, for example: upper, lower, left, right, front or rear, etc., are merely references to the directions of the attached drawings. Thus, the directional terminology is used for purposes of illustration and is not intended to be limiting of the invention.
For some terms or principles that may be involved in the present invention, the following description is given by way of example and not limitation:
Mie scatter (MIE SCATTERING): is an optical phenomenon, which is a case of scattering. When the particle size is close to or greater than the wavelength λ of the incident light, a large portion of the incident light is scattered in the forward direction, a phenomenon called Mie scattering.
Particle size (particle size): the diameter of a certain scattering particle in air is the diameter of the particle corresponding to the intensity of scattered light, in μm.
The first embodiment of the invention provides a method for calibrating a particle counter, which comprises the following steps: calibrating the optical module; and calibrating the photoelectric receiving module. In this embodiment, the two steps are performed in any order, and of course, in other embodiments, only the optical module or the photoelectric receiving module may be calibrated, and this embodiment is only illustrated by the preferred embodiment, which is not limited to this.
Specifically, in this embodiment, the optical module of the particle counter includes, for example, a laser, a power supply for supplying power to the laser, and an optical path shaping unit, and of course, in other embodiments, the optical path shaping unit may not be included, which is not limited by the present invention. When the laser is calibrated, the power supply supplies power to the laser, laser emitted by the laser is output after being shaped by the optical path shaping unit, and the optical path shaping unit is mainly used for obtaining high-quality flat-top light spots, so that the optical quality of light output by the optical module is ensured, and the light is convenient to use subsequently.
The light emitted by the laser outputs high-quality flat-top light spots after being shaped by the light path shaping unit, and the calibration of the optical module is realized through the operation of the flat-top light spots. Specifically, referring to fig. 1, in this embodiment, the calibration of the optical module specifically includes the following steps:
Step 1.1: the method comprises the steps of calibrating the optical module once, and particularly comprises the steps of projecting flat-top light spots output by the optical module onto a laser light spot collector such as a CCD camera, and judging whether the light spots displayed by the CCD camera meet the requirements. The requirement standard mainly comprises whether the size of the light spot meets the requirement and whether the light intensity of the light spot is uniformly distributed, and other requirement standards can be formulated according to actual requirements in the actual calibration process. The preliminary calibration in this embodiment eliminates defective products that do not meet the requirements through manual inspection, and of course, in other embodiments, the preliminary calibration may also be performed by an automated machine, which is not specifically limited in the present invention. In this embodiment, a relatively convenient and common CCD camera is used as the laser spot collector, and in other embodiments, the laser spot collector may also use a facet APD or PIN detector to build a three-dimensional scanning detection device, which is not particularly limited in the present invention. The primary calibration aims at eliminating defective products with obvious unqualified light sources and improving the efficiency of the subsequent secondary calibration.
After the primary calibration is finished, the optical module qualified in the primary calibration is subjected to the secondary calibration in the step 1.2, wherein the secondary calibration comprises the steps of accessing an optical power meter, calculating the total power of light output by the optical module, and enabling the total power of the light output by the optical module to be consistent with the standard power by adjusting a power supply for supplying power to a laser, thereby finishing the secondary calibration of the optical module. Through the secondary calibration, the output light power of the optical module is uniformly adjusted, the consistency of the light source is ensured, the counting accuracy and precision of the particle counter are improved, and the product consistency is ensured.
In this embodiment, the calibration of the optical module includes a primary calibration and a secondary calibration, and in other embodiments, only one calibration or a secondary calibration may be performed for cost or other considerations, and only the best embodiment is selected for illustration, but the invention is not limited thereto.
Referring to fig. 2, the photoelectric receiving module of the present embodiment includes a photodiode and a pre-amplifying circuit electrically connected. Calibrating the photoelectric receiving module, comprising the following steps of 2.1: providing a laser light source, so that the illumination of the laser light source completely covers and irradiates the photodiode; step 2.2: and measuring the output voltage of the pre-amplifying circuit, and regulating the output voltage of the pre-amplifying circuit to be consistent with the standard voltage through a potentiometer.
The laser light source in the step 2.1 is an external reference light source for tooling so as to provide illumination for the photodiode, and the external reference light source is a flat-top beam laser light source. When the calibration is performed, the illumination of the laser light source completely covers and irradiates the photodiode, the output voltage of the pre-amplifying circuit is measured through the universal meter, the circuit part of the pre-method in the embodiment comprises the potentiometer, and the output voltage of the calibrated photodiode and the output voltage of the pre-amplifying circuit are the same as the standard voltage through adjusting the potentiometer, so that the calibration work of the photoelectric receiving module is realized. Through the calibration of the photoelectric receiving module, the consistency of the photoelectric receiving module is ensured, and the accuracy and precision of the particle counter are further improved.
Fig. 3 is a particle counter according to a second embodiment of the present invention. Referring to fig. 3, the particle counter of the present embodiment includes an optical module, an optical working area, a photoelectric receiving module, and a data processing and comparing module, which are sequentially arranged. The optical module and the photoelectric receiving module adopt the structure and the calibration method in the first embodiment, the optical working area comprises a photosensitive working area and an optical collector such as a Mie scattering collector, and the data processing and comparing module comprises a comparator circuit, a potentiometer and a processor.
Fig. 4 is a schematic diagram illustrating a method for operating a particle counter according to a second embodiment of the present invention. Referring to fig. 4, the working method of the particle counter of the present embodiment includes the following steps: the optical module or/and the photoelectric receiving module of the particle counter are calibrated, and the calibration method refers to the calibration method in the first embodiment.
Step two: the threshold voltages of the different particle sizes of the particle counter are marked. Referring to fig. 5, a particle generator sends out particles with a certain concentration and a certain fixed particle size, the particles with a certain concentration are counted by a standard particle counter to obtain a standard particle number, then the particles with the same size and the same concentration are passed through a particle counter to be marked, and the threshold voltage of the particle counter to be marked is adjusted by a potentiometer, so that the deviation between the count value of the particle counter to be marked and the standard particle number is kept within +/-20% under the condition of the same flow, and the marking of the threshold voltage of the particle with a certain fixed size of the particle counter to be marked is realized.
For example, particles with a concentration of 300 ten thousand particles/cubic foot and an air inflow rate of 0.1 cubic foot/min and 0.3 mu m are introduced into a photosensitive working area of a standard particle counter, and the standard particle counter counts 30 ten thousand particles with a particle number of 0.3 mu m in one minute by taking a one-minute flow as an example, and the 30 ten thousand particles are counted as a standard particle number; then, particles with the same concentration of 300 ten thousand/cubic foot and the air inflow rate of 0.1 cubic foot/min and 0.3 mu m are introduced into a photosensitive working area of the particle counter to be marked, and the threshold voltage of the particle counter to be marked is regulated through a potentiometer, so that the deviation between the count value of the particle counter to be marked and the particle number counted by the standard particle counter in the same time is +/-20 percent, namely, the count value of the particle counter to be marked in one minute is regulated to be between 24 ten thousand and 36 ten thousand, and the marking of the particle counter to be marked to the threshold voltage of 0.3 mu m is completed. Similarly, the threshold voltage of particles having a particle diameter of 0.5 μm or 1.0 μm is marked, and after the marking, the third step is performed. It should be noted that, in other embodiments, the particle size of the particles may be freely selected and the number of particles is not limited, and this embodiment is merely an example, and the present invention is not limited thereto.
Step three: and (3) introducing particle airflow to be detected into a light field output by the optical module, namely a photosensitive working area, and comparing and distinguishing the particle number of each particle size through output voltage to realize particle classification counting. Specifically, in this embodiment, for example, counting of particles of 0.3 μm, 0.5 μm and 1.0 μm in the particle airflow to be detected can be performed according to threshold voltages of three types of particles of 0.3 μm, 0.5 μm and 1.0 μm which have been marked. In the particle counter in this embodiment, the optical module and/or the photoelectric receiving module are/is calibrated, so that the product consistency of the particle counter is improved, different classification counting results of different particle counters on the same beam of particle airflow are avoided, and the accuracy and precision of the particle counter are ensured.
The foregoing description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the invention, i.e., all simple and equivalent changes and modifications that may be made in accordance with the claims and specification are intended to be included within the scope of the invention as defined by the appended claims. Furthermore, not all of the objects, advantages, or features of the present disclosure are required to be achieved by any one embodiment or claim of the present disclosure. Furthermore, the abstract sections and the invention names are used solely to assist patent document retrieval and are not intended to limit the scope of the claims. Furthermore, references to "first," "second," etc. in this specification or in the claims are only intended to name a few elements or to distinguish between different embodiments or ranges, and are not intended to limit the upper or lower limit on the number of elements.
Claims (5)
1. The method for calibrating the particle counter is characterized by comprising the following steps of:
Calibrating an optical module, wherein the optical module comprises a laser and a power supply for supplying power to the laser; the optical module further comprises an optical path shaping unit, and the light emitted by the laser is shaped by the optical path shaping unit and then output;
Calibrating a photoelectric receiving module, wherein the photoelectric receiving module comprises a photodiode and a pre-amplifying circuit which are electrically connected;
Wherein, the calibrating the optical module includes:
Step 1.1: performing primary calibration on the optical module, including projecting light output by the optical module to the CCD camera, judging whether light spots presented on the CCD camera meet the requirements, and judging whether the light spots meet the requirements or not, wherein the steps of: whether the size of the light spot meets the requirement, whether the light intensity of the light spot is uniformly distributed or not, and checking a primary calibration result to remove defective products which do not meet the requirement;
Step 1.2: the optical module meeting the requirements is subjected to secondary calibration, which comprises the steps of accessing an optical power meter, calculating the total power output by the laser, and enabling the total power output by the laser to be consistent with the standard power by adjusting a power supply for supplying power to the laser.
2. The method for calibrating a particle counter according to claim 1, wherein calibrating the optoelectronic receiving module comprises:
step 2.1: providing a laser light source, so that the illumination of the laser light source completely covers and irradiates the photodiode;
Step 2.2: and measuring the output voltage of the pre-amplifying circuit, and regulating the output voltage of the pre-amplifying circuit to be consistent with the standard voltage through a potentiometer.
3. The method according to claim 2, wherein the laser light source in step 2.1 is a flat-top beam.
4. A method of operating a particle counter comprising the steps of:
step one: calibrating an optical module or/and a photoelectric receiving module of a particle counter by the calibrating method according to any of claims 1-3;
step two: marking threshold voltages of particles with different particle diameters of the particle counter;
Step three: and introducing particle airflow to be detected into the optical field output by the optical module, and comparing and distinguishing the particle numbers of each particle size through output voltage.
5. The method of claim 4, wherein the step two is marked by a potentiometer method, and the method comprises the steps of:
The particle generator emits particles with a certain particle size and a fixed concentration;
counting the particles with the fixed concentration by a standard particle counter to obtain a standard particle number;
And passing the particles with the fixed concentration through a particle counter to be marked, and adjusting the threshold voltage of the particle counter to be marked through a potentiometer, so that the deviation between the particle count value of the particle counter to be marked and the standard particle number is +/-20% under the condition of the same flow.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202110843845.7A CN113552046B (en) | 2021-07-26 | Particle counter calibration method and working method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110843845.7A CN113552046B (en) | 2021-07-26 | Particle counter calibration method and working method |
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| CN113552046A CN113552046A (en) | 2021-10-26 |
| CN113552046B true CN113552046B (en) | 2024-07-02 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108145606A (en) * | 2017-11-23 | 2018-06-12 | 浙江工业大学 | Polishing fluid bulky grain real time on-line monitoring device in a kind of polishing process |
| CN109142199A (en) * | 2018-09-10 | 2019-01-04 | 苏州苏信环境科技有限公司 | A kind of threshold calibration method of laser dust particle counter channel voltage |
| CN110389093A (en) * | 2018-04-19 | 2019-10-29 | 深圳市世纪天行科技有限公司 | A kind of PM2.5 detection device and PM2.5 detection method |
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108145606A (en) * | 2017-11-23 | 2018-06-12 | 浙江工业大学 | Polishing fluid bulky grain real time on-line monitoring device in a kind of polishing process |
| CN110389093A (en) * | 2018-04-19 | 2019-10-29 | 深圳市世纪天行科技有限公司 | A kind of PM2.5 detection device and PM2.5 detection method |
| CN109142199A (en) * | 2018-09-10 | 2019-01-04 | 苏州苏信环境科技有限公司 | A kind of threshold calibration method of laser dust particle counter channel voltage |
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