Study Of Atmosphere Particle Scattering Characteristics Based On Side-scattering Lidar

This paper reports a following research on laser radar and atmospheric particulate concentration:(1)An overview of research background of the subject,focusing on the classification characteristics of laser radar,and the advantage of measurement of PM2.5 concentration,and the development process and current situation of atmospheric aerosol.(2)The characteristics of Gaussian beam and transmission in a vacuum were illuminated.The composition of the atmosphere,and the interaction of atmospheric aerosol and photons were also illuminated,concentrating on the Mie scattering characteristics and simple explained the Monte Carlo model and CCD principle.(3)According to the side-scattering lidar equation and Mie scattering theory,the relational model of the PM2.5 concentration and side-scattered light intensity is built,a method of real-time monitoring PM2.5 concentrations near the ground based on CCD is proposed.A side-scattering lidar apparatus which uses the wavelength of 532 nm laser as light source,CCD as the receiver is designed.Scattering angle betweeno o15 ~ 45 of the side-scatter image echo signal is measured by this apparatus,the gray value of matrix is extracted from the echo signal image.Compared with the results of a PM2.5 monitor for Thermo Fisher Scientific Company,three formulas about PM2.5 concentration and scattering lighting are concluded with a fitting degree better than 0.97.The device has the characteristics of convenient operation,mobile convenient,real-time monitoring,low cost.Near the ground has a higher precision and practicality point than the backscatter lidar,which will play a significant role in investigating the movement of PM2.5 and depicting pollutant distribution.(4)In order to inverse atmospheric side-scattering coefficient profile based on CCD,The atmospheric side-scattered light intensity whose scattering angles within the range of o o33(25)145 is measured.A new approach that can reduce noise effectively is proposed and six kinds of original echo signal pseudo-color pictures are drew.The space scattering angle is converted to plane scattering angle,which contributes to find a new method of handling the relationship between the CCD pixel corresponds with the scattering angle and this method can greatly simplifies the calculation.In order to study the multi-scattering problem detecting the atmospheric aerosols in the horizontal direction by laser,the paper established a Monte Carlo simulation model of side-scattering lidar,The spatial distribution of total weight photon normalized value that were received by photon detector was obtained by Using semi-analytical Monte Carlo method and rigorous simulation parameters.It is very consistent that the simulation result compares with side-scattering lidar experimental results,which provides some theoretical reference value for utilizing side-scattering lidar for detecting atmospheric aerosols.