Development Of Aerosol Photometer Based On Optical Scattering Principle

With the progress of science and technology,medical,electronic and other industries have become more and more strict requirements for air cleanliness,and put forward more and more strict requirements for aerosol mass concentration detection.Light scattering method is widely used in various air environment detection devices because of its advantages of non-contact and high real-time.Based on the principle of light scattering method,an aerosol photometer based on the principle of forward scattering of particle group is designed in this paper.The main contents of the paper include:This paper expounds the research background and significance of aerosol mass concentration measurement,introduces the research status of aerosol mass concentration detection at home and abroad,focuses on the mathematical principles and practical measurement advantages and disadvantages of single particle light scattering method and particle group light scattering method,and selects the aerosol mass concentration detection method based on optical forward scattering principle.Based on the forward scattering principle of light scattering method,a photomultiplier tube is used to collect the forward scattered light generated by the aerosol under laser irradiation.The weak current signal generated by the photomultiplier tube is converted into voltage signal through the trans resistance amplification circuit.According to the basic principle of particle group light scattering method,the kinematic viscosity specified in the national standard is 4 m~2/s is the standard aerosol to be measured,and the mass concentration is calculated by using the conversion coefficient.The conversion coefficient is calibrated by comparing the output voltage signal of aerosol sensor with the measured value of high-precision aerosol photometer,statistical data and fitting into a linear relationship.According to the functional requirements,this paper designs the following modules: power module,flow control module,human-computer interaction system,data storage and parameter calibration system,etc.The power module provides various efficient,stable and pure power;The flow control system can accurately and stably control the aerosol fluid to enter the sensor according to the flow standard of 28.3L/min;The human-computer interaction system is responsible for data display,measurement process control,etc;The parameter calibration system is used for the calibration of various parameters to improve the accuracy of data sampling calculation.After the performance test of photoelectric conversion circuit and flow control system,the aerosol mass concentration inversion experiment with ATI-2i aerosol photometer as the comparison instrument is carried out in this paper.Finally,the indexes of the whole machine are tested according to the national standard calibration specification,and the test results can meet the requirements of the calibration specification.