WO2023005016A1 - 粒子计数器标定方法及粒子计量方法 - Google Patents

粒子计数器标定方法及粒子计量方法 Download PDF

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WO2023005016A1
WO2023005016A1 PCT/CN2021/126511 CN2021126511W WO2023005016A1 WO 2023005016 A1 WO2023005016 A1 WO 2023005016A1 CN 2021126511 W CN2021126511 W CN 2021126511W WO 2023005016 A1 WO2023005016 A1 WO 2023005016A1
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particle
calibration process
particle counter
laser
calibration
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PCT/CN2021/126511
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English (en)
French (fr)
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王少永
惠旅锋
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苏州苏信环境科技有限公司
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/10—Investigating individual particles
    • G01N15/14—Optical investigation techniques, e.g. flow cytometry
    • G01N15/1434—Optical arrangements
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/02—Investigating particle size or size distribution
    • G01N15/0205—Investigating particle size or size distribution by optical means
    • G01N15/0211—Investigating a scatter or diffraction pattern
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/10—Investigating individual particles
    • G01N15/14—Optical investigation techniques, e.g. flow cytometry
    • G01N2015/1486—Counting the particles
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume or surface-area of porous materials
    • G01N15/10—Investigating individual particles
    • G01N15/14—Optical investigation techniques, e.g. flow cytometry
    • G01N2015/1493—Particle size

Definitions

  • the invention belongs to the technical field of measurement, in particular to a calibration method for calibrating an optical particle counter and a measurement method using the particle counter.
  • Light scattering laser particle counters are generally used to measure the number and particle size distribution of dust particles per unit volume in a clean environment. It is based on the principle of Mie scattering. After the detection laser of the optical module is scattered by dust particles, it is received by the photoelectric receiving module and generates a pulse signal. The pulse signal is output and amplified, and then the signal is processed. By comparing with the standard particle signal, Express the comparison results with different parameters. It is widely used in medicine, precision machinery, microbiology and other industries. It is also one of the main measurement equipments of authoritative institutions such as epidemic prevention stations, disease control centers and quality supervision institutes. With the gradual implementation of the GMP certification system and the analysis of the spread of diseases by particles in aerosols, the application of particle counters is becoming more and more extensive.
  • the existing particle counter calibration method is generally that the inspector blindly adjusts the voltage threshold of the comparator of each particle channel, so that the particle count of each channel is roughly the same as that of the standard particle counter. Obviously, the calibration efficiency is low, the accuracy is poor, and it is difficult to achieve consistency among multiple (each) particle counters. It can be seen that for enterprises that produce particle counters, the existing calibration methods are not ideal, and the optical module and photoelectric receiving module of the particle counter cannot be effectively calibrated, which directly affects the improvement of production efficiency and product quality. Yield optimization.
  • the corresponding existing particle measurement methods also have corresponding defects, which cannot accurately collect voltage pulse signals, especially when the particle concentration is high, the measurement results are not ideal, the particle size distribution cannot be refined, and the application requirements cannot be met.
  • the present invention aims to solve some, all or potential problems of the above-mentioned prior art.
  • One aspect of the present invention provides a particle counter calibration method, which is used for the calibration of the particle counter before it is put into use.
  • Another aspect of the present invention provides a corresponding particle measurement method for testing the particle size and distribution of air dust particles.
  • Mie scattering is an optical phenomenon, which belongs to a kind of scattering. When the size of the particle is close to or larger than the wavelength ⁇ of the incident light, most of the incident light will be scattered along the forward and vertical directions. This phenomenon is called Mie scattering.
  • Particle size The diameter of a certain scattering particle in the air, which is the diameter of the particle corresponding to the intensity of the scattered light, in ⁇ m.
  • Particle concentration the number of discrete particles not smaller than the specified particle size existing in the unit volume of the measured air within the specified sampling flow rate and sampling time.
  • Standard particle counter A particle counter that has been compared by national organizations and has obtained satisfactory results.
  • the measurement principle of the particle counter in the present invention is: in the uniform light field (laser working area) output by the optical module, through the air flow of the particles, the light scattered by a single particle through Mie scattering is collected by the Mie scattering collector, and then irradiated to On the photosensitive element of the photoelectric receiving module, the energy is converted into a voltage pulse signal through a pre-amplification circuit, the voltage pulse signal is collected, and the particle size and distribution are determined by an algorithm.
  • the method for calibrating the particle counter includes: a first calibration process: calibrating the laser working area of the particle counter; a second calibration process: passing a gas stream of particles with a fixed concentration and a predicted particle size through the calibrated laser working area, A Labview acquisition system with a high-speed ADC board is used to calibrate the threshold voltage corresponding to the predicted particle size; auxiliary calibration process: use peripheral tooling to calibrate the photoelectric receiving module of the particle counter, and the peripheral tooling includes providing a uniform A peripheral laser of the laser; wherein, the auxiliary calibration process has no time sequence relationship with the first calibration process and the second calibration process.
  • 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 simultaneously with the first calibration process or the second calibration process, which is not limited.
  • Labview is a system engineering software specially designed for test, measurement and control applications, which can quickly access hardware and data information.
  • the photoelectric receiving module of the particle counter includes a photosensitive element and a preamplifier circuit; during the auxiliary calibration process, the uniform laser light is completely covered and irradiated on the photosensitive element, and a multimeter is used to measure the actual output voltage of the preamplifier circuit; Comparing the actual output voltage with the design theoretical value of the output voltage of the preamplifier circuit; if the actual output voltage is inconsistent with the design theoretical value, setting a correction coefficient according to the ratio between the two.
  • the photoelectric receiving module also includes an EEPROM (electrically erasable programmable read-only memory); during the auxiliary calibration process, the actual output voltage and the correction coefficient are written into the EEPROM.
  • EEPROM electrically erasable programmable read-only memory
  • EEPROM is a memory chip that does not lose data after power failure, and is generally used in plug and play.
  • the main control board of the particle counter is inserted during the counting work, and the correction coefficient can be read to correct the result of the counting work, so that the counting result will not be affected by the photoelectric
  • the difference between the actual output voltage of the receiving module and the design theoretical value produces a deviation to ensure the reliability and accuracy of the counting results.
  • the auxiliary calibration process also includes numbering the photoelectric receiving module, recording the serial number of the photoelectric receiving module and the corresponding correction coefficient.
  • the correction coefficient corresponding to the number is written into the memory of the corresponding particle counter main control board, and the correction coefficient is called to perform the counting result during counting. Amended to ensure the accuracy of counting results.
  • Labview collects the waveform output by the preamplifier circuit, statistically analyzes the peak value of each waveform, and then marks the threshold voltage of the particles with the predicted particle size; at least four different Predict the particle size, distinguish and mark the threshold voltage corresponding to at least 4 kinds of predicted particle sizes.
  • the optical module of the particle counter includes a laser and a beam shaping structure; the beam shaping structure includes a lens; before the first calibration process, the output beam of the laser is shaped to obtain a working beam; the beam shaping structure includes a lens, The working beam is a top-hat beam; in the first calibration process, the light spot of the laser working area is calibrated by adjusting the position of the lens.
  • the first calibration process collect the light spot of the working beam, measure whether the size of the light spot meets the preset value, and evaluate whether it is a light spot with uniform light intensity.
  • the measurement of the size of the light spot can be performed simultaneously with the evaluation of whether the light intensity in the light spot is uniform, or the size of the light spot can be measured first, and then evaluated when the size of the light spot meets the preset value that meets the counting requirements. Whether the light intensity in the spot is uniform; if the measured spot size is inconsistent with the preset value, adjust the distance between the lens and the laser, and adjust the spot size of the working beam.
  • the first spot cutting fixture is used to cut out the first working spot of the preset area of the working beam at the starting point of the laser working area, and connect it to the power meter; calculate the first For the total power of the working spot, the power supply of the laser is adjusted accordingly, so that the total power of the first working spot is consistent with the preset standard total power; and the average light intensity of the first working spot is calculated.
  • a second spot cutting fixture is also used to cut out a second working spot of the preset area of the working beam at the end point of the laser working area, and connect it to a power meter; 2.
  • the average light intensity of the working spot is also used to cut out a second working spot of the preset area of the working beam at the end point of the laser working area, and connect it to a power meter; 2.
  • the average light intensity of the working spot is also used to cut out a second working spot of the preset area of the working beam at the end point of the laser working area, and connect it to a power meter; 2.
  • the average light intensity of the working spot is also used to cut out a second working spot of the preset area of the working beam at the end point of the laser working area.
  • the difference percentage range between the average light intensity of the first working light spot and the average light intensity of the second working light spot is between -10% and +10%, it is determined that the first calibration process is completed. That is, the spot adjustment of the working beam is completed.
  • the particle counting method provided by another aspect of the present invention includes: adopting the particle counter calibration method of the present invention to calibrate the particle counter; after that, collecting the voltage pulse signal output by the preamplifier circuit to distinguish the particle size and particle size distribution .
  • Adopt high-speed analog-to-digital converter to collect described voltage pulse signal;
  • the acquisition speed of described high-speed analog-to-digital converter is more than 10MSPS (sampling million samples per second per second);
  • the ASIC device is integrated on the main control board of the particle counter used for metering, including FPGA.
  • FPGA Field Programmable Gate Array, Field Programmable Logic Gate Array
  • PAL and GAL It emerged as a semi-custom circuit in the field of application-specific integrated circuits (ASICs).
  • the FPGA reads the correction coefficient and runs a resolution algorithm for resolution; the resolution algorithm uses the correction coefficient to adjust the resolution of the particle size.
  • the calibration adopts the Labview acquisition system with a high-speed ADC board, which changes the traditional way of relying on manual and standard particle counters for calibration, and can calibrate the particles at a higher level of precision. diameter and its corresponding threshold voltage; through the discrete auxiliary calibration process, the photoelectric receiving module can be calibrated and analyzed; the particle counter calibrated by the calibration method of the present invention has good consistency among multiple particle counters; It is conducive to the further promotion and development of measurement technology, and promotes the improvement of production efficiency and the optimization of product yield of particle counter manufacturers.
  • the particle metering method of another aspect of the present invention based on the particle counter calibrated by the calibration method of the present invention, is used to measure, and can effectively distinguish the complete range of particle diameters, such as 0.2 ⁇ m, 0.3 ⁇ m, 0.4 ⁇ m, etc., and can be finer Optimize the particle size distribution and raise the particle concentration to a higher level.
  • the test efficiency is high and the reliability is good, and the accuracy of the test results can be further improved by reading the correction coefficient.
  • Fig. 1 is a schematic diagram of the structure of a particle counter according to Embodiment 1 of the present invention.
  • FIG. 2 is a schematic diagram of the process of the particle counter calibration method according to Embodiment 1 of the present invention.
  • FIG. 3 is a schematic diagram of the measurement of the first working spot in Embodiment 1 of the present invention.
  • FIG. 4 is a schematic diagram of the measurement of the second working spot according to Embodiment 1 of the present invention.
  • FIG. 5 is a schematic diagram of auxiliary calibration in Embodiment 1 of the present invention.
  • Fig. 6 is a schematic diagram of a particle counting method in Embodiment 1 of the present invention.
  • FIG. 7 is a schematic diagram of spot collection of working beams according to Embodiment 2 of the present invention.
  • the particle counter of this embodiment example is composed of an optical module providing a working beam, a laser working area for detection, and a photoelectric receiving module for receiving and converting optical signals.
  • the laser working area is a photosensitive working area and a Mie scattering collector.
  • the optical module includes a laser as a laser light source and its power supply components. By adjusting the power supply of the laser, the output light intensity of the laser light source can be adjusted.
  • the example particle counter is provided with an optical path shaping structure near the output end of the laser to shape the Gaussian spot of the output beam of the laser to obtain a working beam.
  • the spot formed by the working beam in the laser working area is flat-topped and uniform.
  • the photosensitive element in this embodiment is a photodiode, and other photosensitive elements such as phototransistors are used in some implementation situations, which is not limited.
  • the particle size calibration equipment used in this embodiment is a Labview acquisition system with a high-speed ADC board. In the counting work of the sample particle counter, the results of particle size and distribution are obtained through ADC digital-to-analog conversion and FPGA/ASIC operation, according to the particle size range algorithm.
  • the method for calibrating the particle counter includes: the first calibration process: calibrating the laser working area of the particle counter; In the laser working area, the Labview acquisition system with a high-speed ADC board is used to calibrate the threshold voltage corresponding to the predicted particle size; auxiliary calibration process: use peripheral tooling to calibrate the photoelectric receiving module, and the peripheral tooling includes providing uniform Laser peripheral lasers.
  • the auxiliary calibration process has no time sequence relationship with the first calibration process and the second calibration process.
  • the specific operation of the auxiliary calibration process is performed between the first calibration process and the second calibration process.
  • the beam shaping structure of the particle counter shapes the output beam of the laser to obtain the working beam.
  • the beam shaping structure includes lenses, and the working beam is a flat-top beam.
  • the working beam obtained after shaping is calibrated in the first calibration process to make it meet the application requirements.
  • the first spot cutting fixture is used to cut out the first working spot of the preset area of the working beam at the starting point of the laser working area, and connect it to the power meter; A total power of the working spot, adjust the power supply of the laser accordingly, so that the total power is consistent with the preset standard total power; calculate the average light intensity of the first working spot.
  • the second spot cutting fixture uses the second spot cutting fixture to cut out the second working spot of the working beam with the same preset area as the first working spot at the end point of the laser working area, and connect it to the power meter; calculate the average light intensity of the second working spot .
  • the apertures of the first spot cutting jig and the second spot cutting jig are the same, and the size of the spot projected on the optical power meter is kept consistent.
  • the average light intensity calculated in the case of the two fixtures can be used to determine whether the optical path shaping has been adjusted.
  • the light path is considered to be Adjusted well, otherwise the light spot is not adjusted well, you need to continue to adjust.
  • the length of the second spot cutting jig is longer than that of the first spot cutting jig, so it can be respectively set at the starting point and the ending point of the laser working area.
  • the light spots are intercepted at multiple positions in the laser working area for testing, and it is not necessary to only set the light spot cutting fixture at the starting point and the end point, and it is not limited.
  • a multimeter is used to test the actual output voltage of the current preamplifier circuit. Comparing the actual output voltage with the designed theoretical value of the output voltage of the preamplifier circuit of the particle counter, if the actual output voltage is inconsistent with the designed theoretical value, a correction coefficient is set according to the ratio between the two.
  • the design theoretical value of the output voltage can be obtained by calculation.
  • the uniform laser light intensity of the peripheral laser can be known.
  • the standard value of the photoelectric conversion rate of the photodiode of the particle counter is provided by the photodiode manufacturer when it leaves the factory.
  • the design theory of the output voltage can be calculated. value.
  • the power of the uniform laser is 0.5 ⁇ W
  • the photoelectric conversion rate of the photodiode is 0.5A/W
  • the amplification gain of the preamplifier circuit is 4000000 ⁇
  • the theoretical value of the output voltage is 1V.
  • the measured actual output voltage of the preamplifier circuit is only 0.9V
  • the EEPROM records the actual output voltage of 0.9V and the correction factor of 0.9( Or record as a percentage as 90%).
  • the photoelectric receiving module is also provided with an EEPROM.
  • the measured actual output voltage and corresponding correction coefficients are written into the EEPROM.
  • the EEPROM is inserted into the main control board, and the FPGA can read the correction coefficient in the EEPROM, and the resolution algorithm uses the correction coefficient to adjust the resolution of the particle size.
  • the particles with the predicted particle size are used in the laser working area to collect the waveform output by the preamplifier circuit, and the peak value of the waveform is statistically analyzed, and the threshold voltage corresponding to the predicted particle size is marked.
  • the example method includes: passing 0.3 ⁇ m particles, then using Labview to collect the waveform output by the preamplifier circuit, statistically analyzing the peak value of each waveform, and then marking the threshold voltage of the 0.3 ⁇ m particles.
  • the acquisition speed of the high-speed analog-to-digital converter of the present embodiment is more than 10MSPS (sampling million samples per second per second), and the ADC that the example adopts is the AD9629 type analog-to-digital converter of ADI Company (Adeno Semiconductor Technology Co., Ltd.) device.
  • the particle measurement method of the present embodiment is to calibrate the particle counter according to the particle counter calibration method of the present embodiment; adopt a high-speed analog-to-digital converter to collect voltage pulse signals; calculate the threshold voltage according to Labview during calibration, Identify the particle size corresponding to the collected waveform.
  • the voltage pulse signal is input to FPGA, and the particle size and distribution are calculated.
  • the complete range of particle size can be distinguished, such as 0.2 ⁇ m, 0.3 ⁇ m, 0.4 ⁇ m, etc., and even the particle size distribution can be refined, and the particle concentration can be raised to a higher level. It is an ordinary comparator more than 100 times.
  • the general control part can use FPGA or other special control chips, which is not limited.
  • the difference between the second embodiment and the first embodiment mainly lies in that, in the first calibration process, the spot of the working beam is collected and evaluated.
  • a laser spot collector is used, specifically a CCD camera with adjustable front and rear positions on the slide rail to obtain multiple spot information of the working beam, and statistically analyze whether the spot size meets the requirements according to the obtained multiple spot information of the working beam. Whether the light intensity distribution is uniform. If the spot size is inconsistent with the preset value, adjust the beam shaping structure.
  • the general method is to adjust the distance between the lens and the laser, and then collect the spot information for evaluation until the spot size meets the preset value.
  • a more convenient CCD camera is used for collection.
  • the laser spot collector can also use a small panel APD or PIN detector to build a three-dimensional scanning detection device, which is not specifically limited in the present invention.
  • Embodiment 1 another difference from Embodiment 1 is that in the auxiliary calibration process, no EEPROM is set, but an external recording method is used to number each photoelectric receiving module, record the number and the corresponding correction coefficient,
  • an external recording method is used to number each photoelectric receiving module, record the number and the corresponding correction coefficient.
  • a label is pasted on the surface of the photoelectric receiving module of the particle counter, and the number and correction factor are marked on the label.
  • the correction coefficient is written into the memory of the main control board for calling by the FPGA.

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Abstract

一种粒子计数器标定方法，包括：第一标定过程：对粒子计数器的激光工作区域进行标定；第二标定过程：将固定浓度的预知粒径的粒子气流通过标定后的激光工作区域，采用带有高速ADC板卡的Labview采集系统标定与预知粒径对应的门槛电压；辅助标定过程：采用外设工装对光电接收模组进行标定，外设工装包括提供均匀激光的激光器。该标定方法改变了传统依赖于人工和标准粒子计数器进行标定的做法，标定效率高、精度好；相应的，粒子计量方法因采用该标定方法标定的粒子计数器实施而具有相应优势，能够更加细化粒径分布，将粒子浓度提升到一个更高的档次，推动计量技术的进一步发展。

Description

粒子计数器标定方法及粒子计量方法 技术领域
本发明属于计量技术领域，尤其涉及用于标定光学粒子计数器的标定方法以及使用粒子计数器的计量方法。
背景技术
光散射式激光粒子计数器一般是用于测量洁净环境中单位体积内尘埃粒子数和粒径分布的仪器。其基于米氏散射原理，光学模组的探测激光经尘埃粒子散射后由光电接收模组接收并产生脉冲信号，该脉冲信号被输出并放大，然后进行信号处理，通过与标准粒子信号进行比较，将对比结果用不同的参数表示出来。广泛应用于医药、精密机械、微生物等行业中，也是防疫站、疾控中心、质量监督所等权威机构的主要计量设备之一。随着GMP认证制度逐步实施，以及气溶胶中颗粒对于疾病的传播分析，粒子计数器的应用越来越广泛。然而，现有的粒子计数器产品计数测量的准确性、可靠性、一致性还不能完全满足应用要求，其中一个重要原因存在于现有的粒子计数器投入使用前没有完全标定，或者标定方法效果没有达到要求。现有的粒子计数器标定做法一般是检验员盲调各粒子通道比较器电压阈值，使各通道粒子计数与标准粒子计数器大致相同。显然，标定效率低、精确度差，也很难实现多(每)台粒子计数器之间的一致性。可知，对于生产粒子计数器的企业而言，采用现有的标定方法，效果不理想，不能分别对粒子计数器的光学模组和光电接收模组进行有效的标定，直接影响企业生产效率的提高和产品良率的优化。相应的现有粒子计量方法也存在相应缺陷，无法精确采集电压脉冲信号，特别当粒子浓度较高，测量结果不理想，无法细化粒径分布，不能满足应用需求。
因此目前十分需要研究有效可行的粒子计数器标定方法以及相应的粒子计量方法，能够适用于粒子计数器的标定和采用粒子计数器的计量工作，提高投入使用的粒子计数器的精确性和可靠性，以此进一步推动计量技术的深入发展及广泛应用。
发明内容
本发明是为了解决上述现有技术的部分、全部或潜在问题，本发明一方面提供了粒子计数器的标定方法，用于粒子计数器投入使用前的标定工作。本发明另一方面提供了相应的粒子计量方法，测试空气尘埃粒子颗粒的粒径及其分布。
对于本发明可能涉及的一些名词或原理，进行示例性而非限定的说明如下：
米氏散射(Mie scattering)，是一种光学现象，属于散射的一种情况。当粒子的大小接近于或者大于入射光线的波长λ的时候，大部分的入射光线会沿着前进和垂直的方向进行散射，这种现象被称为米氏散射。
粒径(particle size)：空气中某种散射粒子的直径，是与散射光的强度相对应的粒子的直径，单位μm。
粒子浓度(particle concentration):在规定的采样流量和采样时间内，被测空气单位体积中存在的不小于指定粒径的离散粒子的个数。
标准粒子计数器：经国家组织比对，并获得满意结果的粒子计数器。
本发明中粒子计数器计量原理是：在光学模组输出均匀的光场(激光工作区域)中，通过粒子的气流，单个粒子通过米氏散射出来的光被米氏散射收集器收集，然后照射到光电接收模组的光敏元件上，通过前置放大电路将能量转化为电压脉冲信号，采集电压脉冲信号，利用算法分辨粒径大小和分布。
本发明提供的粒子计数器标定方法包括：第一标定过程:对粒子计数器的激 光工作区域进行标定；第二标定过程：将固定浓度的预知粒径的粒子气流通过标定后的所述激光工作区域，采用带有高速ADC板卡的Labview采集系统标定与所述预知粒径对应的门槛电压；辅助标定过程：采用外设工装对粒子计数器的光电接收模组进行标定，所述外设工装包括提供均匀激光的外设激光器；其中，所述辅助标定过程与所述第一标定过程、所述第二标定过程无时序关联。即辅助标定过程可以在第一标定过程之前、第二标定过程之后或者在第一、第二标定过程之间进行，也可以与第一标定过程或第二标定过程同时进行，并不限定。其中Labview是专为测试、测量和控制应用而设计的系统工程软件，可快速访问硬件和数据信息。
所述粒子计数器的光电接收模组包括光敏元件和前置放大电路；所述辅助标定过程中，将所述均匀激光完全覆盖照射光敏元件，采用万用表测量所述前置放大电路的实际输出电压；将所述实际输出电压与所述前置放大电路的输出电压的设计理论值比对；如所述实际输出电压与所述设计理论值不一致，则根据两者之间的比例设定修正系数。
所述光电接收模组还包括EEPROM(带电可擦可编程只读存储器)；所述辅助标定过程中，将所述实际输出电压与所述修正系数写入所述EEPROM。EEPROM是一种掉电后数据不丢失的存储芯片，一般用在即插即用。将所述实际输出电压与所述修正系数写入EEPROM后，在进行计数工作时插入粒子计数器的主控板，所述修正系数能被读取以修正计数工作的结果，使得计数结果不因光电接收模组的实际输出电压与设计理论值的差异而产生偏差，保障计数结果的可靠性和准确性。
所述辅助标定过程中还包括对所述光电接收模组进行编号，记录所述光电接 收模组的编号及相应的所述修正系数。在后续进行计数工作时，根据计数所使用的粒子计数器的光电接收模组的编号，将编号对应的修正系数写入相应粒子计数器主控板的存储器，计数时调用所述修正系数对计数结果进行修正，以保障计数结果的准确性。通过辅助标定过程中分析计算前置放大电路的输出电压设定修正参数，一方面提高了粒子计数器在计量工作应用时的精确度，另一方面使得粒子计数器前置放大电路的实际输出电压容许与设计理论值有差异，有利于粒子计数器制造中的灵活性，一定程度上降低生产难度。
所述第二标定过程中，Labview采集所述前置放大电路输出的波形，统计分析每个波形的峰值，然后标记出所述预知粒径的粒子的门槛电压；至少逐次通入4种不同的预知粒径，分辨标记至少4种预知粒径对应的门槛电压。
粒子计数器的光学模组包括激光器和光束整形结构；所述光束整形结构包括镜片；所述第一标定过程之前，将所述激光器的输出光束进行整形得到工作光束；所述光束整形结构包括镜片，所述工作光束为平顶光束；所述第一标定过程中，通过调节所述镜片的位置标定所述激光工作区域的光斑。
所述第一标定过程中，采集所述工作光束的光斑，测量光斑的大小是否符合预设值，评估是否为光强均匀的光斑。可以将测量所述光斑的大小与评估所述光斑内光强是否均匀同步进行，也可以先测量所述光斑的大小，当所述光斑大小符合满足计数需要的预设值时，再评估所述光斑内光强是否均匀；如测量得到光斑大小与所述预设值不一致，则调节所述镜片与激光器的间距，调整所述工作光束的光斑大小。
所述第一标定过程中，采用第一光斑切割夹具，在所述激光工作区域的起始点切割出所述工作光束的预设面积的第一工作光斑，接入功率计；计算所述第一 工作光斑总功率，相应调整激光器供电，使所述第一工作光斑总功率与预设标准总功率保持一致；计算所述第一工作光斑的平均光强。
所述第一标定过程中，还采用第二光斑切割夹具，在所述激光工作区域的终结点切割出工作光束的所述预设面积的第二工作光斑，接入功率计；计算所述第二工作光斑的平均光强。
若所述第一工作光斑的平均光强与所述第二工作光斑的平均光强之间的差异百分比范围在-10％到+10％之间，则判定所述第一标定过程完成。即工作光束的光斑调整完成。
本发明另一方面提供的粒子计量方法，包括：采用本发明一方面的粒子计数器标定方法对粒子计数器进行标定；之后，采集前置放大电路输出的电压脉冲信号，分辨粒径大小和粒径分布。
采用高速模数转换器采集所述电压脉冲信号；所述高速模数转换器的采集速度在10MSPS(每秒采样百万次Million Samples per Second)以上；所述电压脉冲信号输入专用集成电路(ASIC)计算得到粒径大小和分布；所述专用集成电路器件集成在用于计量的粒子计数器的主控板上，包括FPGA。FPGA(Field Programmable Gate Array，现场可编程逻辑门阵列)是在PAL、GAL等可编程器件的基础上进一步发展的产物。它是作为专用集成电路(ASIC)领域中的一种半定制电路而出现的。
所述FPGA读取修正系数，运行分辨算法进行分辨；所述分辨算法采用所述修正系数调整粒径大小的分辨。
与现有技术相比，本发明的主要有益效果：
1、本发明一方面的粒子计数器标定方法，标定采用带有高速ADC板卡的 Labview采集系统，改变了传统依赖于人工和标准粒子计数器进行标定的做法，且能够在更高的精度水平对粒径及其对应的门槛电压进行标定；通过分立的辅助标定过程，能够对光电接收模组进行标定与分析；采用本发明标定方法标定的粒子计数器，多台粒子计数器之间的一致性好；极有利于计量技术的进一步推广和发展，推动粒子计数器生产企业生产效率的提高和产品良率的优化。
2、本发明另一方面的粒子计量方法，基于本发明的标定方法标定的粒子计数器后进行计量，能够有效分辨粒径的完整范围，例如0.2μm，0.3μm，0.4μm等等，能够更加细化粒径分布，将粒子浓度提升到一个更高的档次。此外，测试效率高、可靠性好，能够通过读取修正系数进一步完善测试结果的准确性。
附图说明
图1为本发明实施例一的粒子计数器构成示意图。
图2为本发明实施例一的粒子计数器标定方法过程示意图。
图3为本发明实施例一的第一工作光斑测量示意图。
图4为本发明实施例一的第二工作光斑测量示意图。
图5为本发明实施例一的辅助标定情况示意图。
图6为本发明实施例一的粒子计量方法示意图。
图7为本发明实施例二的工作光束光斑采集示意图。
具体实施方式
下面将对本发明具体实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅是本发明的一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
本发明的上述和/或附加的方面和优点从结合下面附图对实施例的描述中将变得明显和容易理解。附图中，相同结构或功能的部分利用相同的附图标记来标记，出于显示清楚的原因必要时并不是所有示出的部分在全部附图中用所属的附图标记来标记。
在下述实施例中采用特定次序描绘了实施例的操作，这些次序的描述是为了更好的理解实施例中的细节以全面了解本发明，但这些次序的描述并不一定与本发明的方法一一对应，也不能以此限定本发明的范围。
需要说明的是，附图中的流程图和框图，图示出按照本发明实施例的方法可能实现的操作过程。也应当注意，在有些作为替换的实现中，方框中所标注的功能也可以并不同于附图中所标注的顺序发生。例如，两个接连地表示的方框实际上可以基本并行地执行，它们有时也可以穿插的执行，依所涉及的步骤要实现的目的而定。也要注意的是，框图和/或流程图中的每个方框、以及框图和/或流程图中的方框的组合，可以用执行规定的功能或操作的专用的基于硬件的系统来实现，或者可以用专用硬件与人工操作结合来实现。
实施例一
本发明实施例一中，如图1所示，本实施例示例的粒子计数器，由提供工作光束的光学模组、进行探测的激光工作区域、进行光学信号接收和转换的光电接收模组构成。其中激光工作区域是光敏工作区及米氏散射收集器。光学模组中有作为激光光源的激光器及其供电部件，通过调节激光器供电可以调节激光光源的输出光强。本实施例中，示例的粒子计数器在靠近激光器输出端设置有光路整形结构，将激光器的输出光束的高斯光斑进行整形得到工作光束，工作光束在激光工作区域形成的光斑是平顶均匀化的。在工作光束的光场中通过固定浓度粒子气 流，单个粒子通过米氏散射收集器后出来的光被光电接收模组收集进行光电信号转换。本实施例的光敏元件是光电二极管，在也有的实施情况中采用其他光敏元件如光敏三极管等，并不限定。本实施例采用的粒径标定设备是带有高速ADC板卡的Labview采集系统。示例的粒子计数器在计数工作中，经ADC数模转换和FPGA/ASIC运算，根据粒径范围算法，得到粒径大小和分布的结果。
本实施例中，如图2所示，粒子计数器标定方法包括：第一标定过程:对粒子计数器的激光工作区域进行标定；第二标定过程：将固定浓度的预知粒径的粒子气流通过标定后的激光工作区域，采用带有高速ADC板卡的Labview采集系统标定与预知粒径对应的门槛电压；辅助标定过程：采用外设工装对光电接收模组进行标定，所述外设工装包括提供均匀激光的外设激光器。辅助标定过程是与第一标定过程、第二标定过程没有时序关联的。实施例中为了便于理解本发明示例的辅助标定过程的具体操作是在第一标定过程与第二标定过程之间进行的。
本实施例中，粒子计数器的光束整形结构将激光器的输出光束进行整形得到工作光束。光束整形结构包括镜片，工作光束为平顶光束。对于整形后得到工作光束在第一标定过程中进行标定，使其符合应用要求。结合图3和图4所示，第一标定过程中，采用第一光斑切割夹具，在激光工作区域的起始点切割出工作光束的预设面积的第一工作光斑，接入功率计；计算第一工作光斑总功率，相应调整激光器供电，使总功率与预设标准总功率保持一致；计算所述第一工作光斑的平均光强。之后采用第二光斑切割夹具，在激光工作区域的终结点切割出工作光束的与第一工作光斑相同的预设面积的第二工作光斑，接入功率计；计算第二工作光斑的平均光强。本实施例中，第一光斑切割夹具和第二光斑切割夹具的孔径相同，保持投射到光功率计上的光斑大小一致，两种夹具情况下计算出来的平均 光强可以判别光路整形有没有调整好，假如偏差控制在10％以内，即第一工作光斑的平均光强与所述第二工作光斑的平均光强之间的差异百分比范围在-10％到+10％之间，就认为光路调整好了，否则光斑没有调整好，需要继续调整。第二光斑切割夹具的长度比第一光斑切割夹具的长度长，由此可以分别设置在激光工作区域的起始点和终结点。在也有的实施情况中在激光工作区域的多个位置截取光斑进行测试，并不一定只有在起始点和终结点设置光斑切割夹具，并不限定。
本实施例中，如图5所示，辅助标定过程中，由外设激光器提供的均匀激光完全覆盖照射光电二极管之后，采用万用表测试当下前置放大电路的实际输出电压。将实际输出电压与该粒子计数器的前置放大电路输出电压的设计理论值比对，如所述实际输出电压与设计理论值不一致，则根据两者之间的比例设定修正系数。输出电压的设计理论值，是可以通过计算得到。一般的情况，外设激光器的均匀激光光强可知，粒子计数器的光电二极管的光电转换率的标准值在光电二极管厂家出厂时提供，根据前置放大电路的增益理论可以计算出输出电压的设计理论值。为了便于理解，举例而言，已知均匀激光的功率是0.5μW，光电二极管的光电转换率是0.5A/W，前置放大电路的放大增益是4000000Ω，则输出电压设计理论值为1V，在同样的光照条件下，测量得到前置放大电路的实际输出电压仅为0.9V，那么，该粒子计数器的修正系数即为1/0.9＝0.9，EEPROM记录该实际输出电压0.9V以及修正系数0.9(或者以百分数形式记录为90％)。
本实施例中光电接收模组还设置有一块EEPROM，在辅助标定过程中，将测量得到的实际输出电压与相应的修正系数写入EEPROM。在采用该粒子计数器进行计数时将EEPROM插上主控板，FPGA就能读取EEPROM里的修正系数，分辨算法采用该修正系数调整粒径大小的分辨。
本实施例中，第二标定过程中在激光工作区域内通过预知粒径的粒子，采集前置放大电路输出的波形，统计分析波形的峰值，标记所述预知粒径对应的门槛电压。示例的做法包括：通过0.3μm的粒子，然后用Labview采集前置放大电路输出的波形，统计分析每个波形的峰值，然后标记出0.3μm粒子的门槛电压。同样的，通过0.5μm的粒子，然后用Labview采集前置放大电路输出的波形，统计分析每个波形的峰值，然后标记出0.5μm粒子的门槛电压；通过1.0μm的粒子，然后用Labview采集前置放大电路输出的波形，统计分析每个波形的峰值，然后标记出1.0μm粒子的门槛电压。本实施例中还通过其他3种不同的预知粒径的粒子气流，进行相似操作。根据粒子计数器的粒径通道数量对应通过多种不同粒径的粒子进行标定。粒径通道数量和需要标定的不同粒径的种类个数可以结合实际应用需要设置，并不限定。
本实施例的高速模数转换器的采集速度在10MSPS(每秒采样百万次Million Samples per Second)以上，示例采用的ADC是ADI公司(亚德诺半导体技术有限公司)的AD9629型模数转换器。
如图6所示，本实施例的粒子计量方法是，先按本实施例的粒子计数器标定方法标定粒子计数器；采用高速模数转换器采集电压脉冲信号；根据标定时Labview计算的出门槛电压，分辨采集到波形所对应的粒径。电压脉冲信号输入FPGA，计算得到粒径大小和分布。采用这种方法可以分辨出粒径的完整范围，例如0.2μm，0.3μm，0.4μm等等，甚至可以更加细化粒径分布，可以将粒子浓度提升到一个更高的档次，是普通比较器的100倍以上。对ADC有很高的要求，采集速度要达到10M以上才能完整分布粒径，一般控制部分可采用FPGA或者其他专用控制芯片，并不限定。
实施例二
如图7所示，实施例二与实施例一的区别主要在于，第一标定过程中，对工作光束的光斑进行采集和评估。采用激光光斑采集器，具体是一个设置在滑轨上前后位置可调的CCD相机获取工作光束的多个光斑信息，根据获得的工作光束的多个光斑信息统计分析光斑大小是否符合要求，光斑内光强分布是否均匀。如果光斑大小与预设值不一致，则调节光束整形结构，一般的做法中是调整镜片与激光器之间的距离，调整后再采集光斑信息进行评估，直至光斑大小符合预设值为止。本实施例中采用较为方便的CCD相机进行采集，当然，在其他实施例中激光光斑采集器还可以利用小面元APD或PIN探测器搭建一个三维扫描检测设备，本发明对此不作具体限定。
本实施例中，与实施例一的另一个区别是在辅助标定过程中，没有设置EEPROM，而是采用外部记录的方式，对每个光电接收模组进行编号，记录编号以及对应的修正系数，示例的做法中在粒子计数器的光电接收模组表面贴有标签，标签上标识了编号及修正系数。后续使用该粒子计数器进行计数时，将该修正系数写入主控板的存储器，供FPGA调用。
本发明为了便于叙述清楚而采用的一些常用的英文名词或字母只是用于示例性指代而非限定性解释或特定用法，不应以其可能的中文翻译或具体字母来限定本发明的保护范围。
还需要说明的是，在本文中，诸如“第一”和“第二”等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要 素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。
以上对本发明进行了详细介绍，本文中应用了具体的个例对本发明的结构及工作原理进行了阐述，以上实施例的说明只是用于帮助理解本发明的方法及核心思想。应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以对本发明进行若干改进和修饰，这些改进和修饰也落入本发明权利要求保护的范围内。

Claims (7)

  1. 粒子计数器标定方法，其特征在于：包括：
    第一标定过程：对粒子计数器的激光工作区域进行标定；
    第二标定过程：将固定浓度的预知粒径的粒子气流通过标定后的所述激光工作区域，采用带有高速ADC板卡的Labview采集系统标定与所述预知粒径对应的门槛电压；
    辅助标定过程：采用外设工装对粒子计数器的光电接收模组进行标定，所述外设工装包括提供均匀激光的外设激光器；其中，所述辅助标定过程与所述第一标定过程、所述第二标定过程无时序关联。
  2. 根据权利要求1所述的粒子计数器标定方法，其特征在于：所述粒子计数器的光电接收模组包括光敏元件和前置放大电路；
    所述辅助标定过程中，将所述均匀激光完全覆盖照射光敏元件，采用万用表测量所述前置放大电路的实际输出电压；
    将所述实际输出电压与所述前置放大电路的输出电压的设计理论值比对；如所述实际输出电压与所述设计理论值不一致，则根据两者之间的比例设定修正系数。
  3. 根据权利要求2所述的粒子计数器标定方法，其特征在于：所述第二标定过程中，Labview采集所述前置放大电路输出的波形，统计分析每个波形的峰值，然后标记出所述预知粒径的粒子的门槛电压；至少逐次通入4种不同的预知粒径，分辨标记至少4种预知粒径对应的门槛电压。
  4. 根据权利要求1-3任意一项所述的粒子计数器标定方法，其特征在于：粒子计数器的光学模组包括激光器和光束整形结构；所述光束整形结构包括镜片；所述第一标定过程之前，将所述激光器的输出光束进行整形得到工作光束；所述 工作光束为平顶光束；所述第一标定过程中，通过调节所述镜片的位置标定所述激光工作区域的光斑。
  5. 粒子计量方法，其特征在于：包括：采用权利要求1-4任意一项所述的标定方法对粒子计数器进行标定；之后，采集前置放大电路输出的电压脉冲信号，分辨粒径大小和粒径分布。
  6. 根据权利要求5所述的粒子计量方法，其特征在于：采用高速模数转换器采集所述电压脉冲信号；所述高速模数转换器的采集速度在10MSPS以上；所述电压脉冲信号输入专用集成电路计算得到粒径大小和分布；所述专用集成电路器件集成在用于计量的粒子计数器的主控板上，包括FPGA。
  7. 根据权利要求6所述的粒子计量方法，其特征在于：所述FPGA读取修正系数，运行分辨算法进行分辨；所述分辨算法采用所述修正系数调整粒径大小的分辨。
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