Design And Experiment Of White LED Light Source Radar System For Low Level Atmospheric Aerosol Detection

In recent years,atmospheric aerosols have a great impact on human production activities.People are concerned about the physical and chemical properties of aerosols and their detection methods.Laser radar is an active optical remote sensing device that uses laser as a light source to achieve atmospheric aerosol detection.It has high detection sensitivity,time and spatial resolution and is widely used in scientific research.However,the lidar is limited by the wavelength of the light source,which has a certain impact on the detection of aerosols.Due to the large blind area detected by the laser radar,it is difficult to observe atmospheric aerosols near the ground.In this paper,a white light LED light source radar system is proposed,which can realize multi-wavelength detection of low-level atmospheric aerosols.The paper mainly completed the following research work:Firstly,this thesis proposes a white LED light source radar aerosol detection system scheme,introduces the system structure and working principle,and elaborates on the two radar splitting schemes and their working principles.Based on the analysis of the white LED spectrum,four detection wavelengths were determined.This project identifies a radar splitting scheme using a combination of dichroic mirrors and filters,and discusses the radar equations and three solving methods under different conditions.Then,according to the white LED light source radar system scheme,this thesis completes the design of the light source emission part,the signal receiving part,and the splitting and detecting part.The LED light source collimation light path,receiving telescope,fiber coupling light path and split light path are designed,and each light path is simulated using ZEMAX.This article selects LED light sources,fiber optics,dichroic mirrors,narrowband filters,and PMTs.Designed and built LED drive circuit and PMT flow pressure conversion and amplifying circuit and mechanical structure of telescope and optical fiber connection.The spectrometer is used to test the optical components.The results are in accordance with the experimental requirements of this project.Finally,according to the radar system parameters,the system’s detection capability is simulated,and the effects of different light source energy and different light source divergence angles on the detection distance are analyzed.A white LED light source radar system was set up,and preliminary aerosol detection experiments were conducted at the radar center of Xi’an University of Technology.The aerosol detection signals and distance squared correction signals at four detection wavelengths were obtained.The data was inverted using the Fernald method.Through the analysis of the experimental results,the feasibility of white light LED light source radar to achieve multi-wavelength low-level atmospheric aerosol detection was verified.