Development Of Low Altitude Imaging Lidar System

As one of the air pollutants emitted by humans,aerosols have seriously affected people’s healthy living standards and the changing patterns of atmospheric climate.So monitoring and managing the aerosol in the air is one of the important measures to adhere to sustainable development.Atmospheric lidar,as one of the effective means to monitor atmospheric aerosols,demonstrates its unique advantages and broad development prospects in atmospheric detection with many achievements.Due to the large detection interval of the meter scattering atmospheric lidar,it cannot achieve full coverage from low to high detection altitude,so it usually has a blind measurement area of several hundred meters near the ground.As an atmospheric environment monitoring technology developed rapidly in recent years based on the imaging principle,atmospheric detection lidar has the advantages of simple structure,low cost and high resolution at low and medium altitudes compared with traditional atmospheric lidar.In order to make up for the shortcoming that meter scattering lidar cannot detect laser echo signals at near ground level,we developed a set of imaging lidar systems to detect low altitude laser echo signals based on the sand imaging basic principle and test and analyze the system functions in this thesis.The specific work is as follows.1)Based on the basic principle of Scheimpflug imaging,we developed an atmospheric imaging detection lidar system consisting of laser,telescope,industrial camera,data analysis software and so on.And the parameters of the system were calibrated.2)We designed the system’s host computer software.According to the functional requirements of the system,the software functions are modularized and split into four parts:image acquisition module,image segmentation module,the data processing module and design of the main control interface,to implement the functions of controlling the camera,saving images,and displaying images in real time.Next,we detected the laser beam in the image and segmented the image to save memory space,calculated the average value of the laser beam and combined it with the theoretical formula to obtain the destination data,designed the main interface of the software and bind functional functions to the controls of the main interface,divided the operation logic of each module to finally realize an upper computer software with comprehensive functions,logical and smooth operation and beautiful interface.3)We tested the atmospheric imaging detection lidar and proved its ability to detect nearground altitude echo signals.After completing the calibration of the system device parameters,the system detects the altitude range of 0.038～2.5 km,the distance resolution is less than 6.8 m in the range of 1 km,and the distance resolution is less than 42.5 m in the range of 1～2.5 km.The high resolution in the detection range indicates that the system can meet the demand of low altitude detection blind area of the meter scattering lidar.We conducted observations with the device and compared and analyzed the variation of echo signal data at different moments of the same night,which proved that the system has a good temporal resolution.We also compared and analyzed the detection data of the system at different air quality moments,and the data variation has a good correlation with air quality.In summary,the imaging lidar built in this thesis has the capability to monitor low-altitude atmospheric aerosols for a long period of time,and will lay the technical foundation for the study of aerosol generation mechanism and evolution process at near-Earth altitude.