In 1908, Gustav Mie analyzed the scattering of spherical particles according to Maxwell’s equations. And he first obtained the calculation method of scattering and absorption of spherical particles illuminated by light waves. It provides a solid theoretical basis for the optical study of particulate matter. All walks of life pay more and more attention to the study of particle detection by light scattering. The scattering method has been widely developed since the 1980s. We make full use of the continuous development of technology and in-depth theoretical research. And dynamic real-time detection and online monitoring have gradually become the development trend for studying the distribution of particles.
A laser particle sensor
, a new particle measuring instrument using a laser as a light source emitter, has been widely used in production and research. The research and application of the United States have always maintained a technological advantage in recent aerosol particle research.. And nearly half of the SCI papers are also published by American researchers. Domestic research is relatively lagging behind and is still in the process of development. The research meets the requirements of the international standard I3320.
2. The overview of the development in foreign countries
The laser particle monitor
based on the Mie scattering theory is relatively mature in developed countries such as the United States, the United Kingdom, Germany, and Japan. We make full use of the continuous efforts of researchers and the exploration of particle measurement technology. Thus there is a breakthrough in accuracy and particle size range. The National Oceanic and Meteorological Administration, Caltech, National Aeronautics and Space Administration, and National Center for Atmospheric Research are currently the world’s leading particle measurement
institutes. Increase the measurement angle through Mie theory and Fraunhofer diffraction theory; we use multiple detection and receiving devices and lateral detection and other methods. Thus the minimum particle size of the measured particles can reach 0.1um, or even reach the nm level.
3. An overview of the development in China
The research on particle size in China began in the 1970s. And domestic researchers focused on using the classic Mie theory to analyze particle size. Its detection range is of 0.5 to 1000pm in the 1980s. In the same year, we established China Microparticles Science. Professor Guo, who was an academician and the chairman of the board of the Chinese Academy of Sciences at the time, established a particle testing committee, a particle preparation committee, and an aerosol committee. Before the mid-1990s, we imported the domestic laser particle size analyzers from developed countries such as the United States, Germany, and Japan, and we base the domestic particle size testing equipment mainly on sedimentation particle size analyzers.
With the continuous development of domestic technology and the continuous deepening of research, the particle size measurement industry is booming, but we have not formed the national standard of the relevant particle size analyzer. The representative research institutes in particle size measurement in China are Peking University, Hong Kong University of Science and Technology, Institute of Earth Environment, Chinese Academy of Sciences and Institute of Atmospheric Physics, Chinese Academy of Sciences.
4. The development trend
We summarize the development trend of measuring atmospheric particle size by laser scattering in the following aspects:
(1) Since laser scattering can realize the advantages of real-time detection, continuous measurement, and long-distance measurement in the area, laser scattering will become the dominant method of measuring the particle’s size.
(2) To meet complex particle systems, it is possible to use a combination of various measurement methods.
(3) With the advent of the Internet, the era of big data and the continuous deepening of research, measuring particles in the future will tend to be intelligent, digital and concise.
(4) Mie theory, as a classical scattering theory, we will be further optimize and specially processe for the measurement of particle sizes in different particle systems.