Principle Design And Performance Simulation Of Aorborne Laser Lidar Based On Multiple Scattering

Cloud plays an essential role in the water circulation system of the earth's atmosphere.If it can detect the macroscopic and microscopic physical properties of the cloud correctly,it will help to weak or even eliminate extreme weather by artificial weather.At present,the airborne instrument into the cloud direct detection cloud characteristic exists the threat of flying safety,and the measurement precision of the ground microwave indirect remote sensing detection method is generally low.Therefore,it is necessary to develop the airborne laser lidar characteristic detection technology,in order to improve the spatial and temporal resolution of the measurement and eliminate the hidden safety of flight.Based on the existing aerosol scattering laser radar technology,this paper studies airborne lidar technology suitable for cloud characteristics detection,focusing on the impact of multiple scattering conditions on the performance of scattered lidar,in order to promote the research process in the field of airborne laser radar and artificial influence in China.Based on the Mie scattering theory of spherical particles,the influence of multiple scattering on the scattering optical properties of spherical particles is analyzed,and the principle design of the near-infrared airborne polarization cloud lidar is proposed and designed,and the system detection performance is simulated and analyzed.First,the relationship between the particle optical parameters and the particle size parameters is analyzed for a single spherical particle model.It is shown that the scattering of the atmosphere and small aerosol particles to the laser can be ignored when the laser beam is acting with the cloud particles.In order to improve the precision of detection of cloud particles by laser lidar,the influence of multiple scattering on the echo signal of atmospheric lidar is simulated and analyzed.The influence of excitation wavelength,telescope receiving field angle,and number density of cloud particles on multiple scattering ratio are studied respectively,and the single scattering and multiple scattering lidar equations are solved by Klett method respectively.The influence of multiple scattering conditions on the extinction coefficient and scattering coefficient of cloud particles is analyzed,which is about 2?3 times that of single scattering.In order to improve the detection distance of the polarization cloud lidar and detect the particle distribution in the cloud more effectively,a scheme for detecting the characteristics of the cloud particles by the airborne near infrared polarization laser radar is proposed.The phase state of the cloud particles is discriminate using the depolarization theory of non-spherical particles,and the airborne temperature sensor and the particle measurement system are combined to retrieve the particles.In order to reduce the detection blind area and improve the detection distance,the spatial distribution of the characteristics of the cloud particles is designed and an external optical fiber guided airborne polarization laser lidar system is designed.The cloud laser radar analysis model is created.When the cloud extinction coefficient is 3.91 km-1,the signal to noise ratio of the 1550nm excitation source is about 200 and 1000 at the detection distance of 1km,while the signal to noise ratio of the 1064nm excitation source is about 100 and 1000 respectively.The analysis results show that the excitation wave length 1550nm is in the detection of cloud particle characteristics.It has a certain advantage,and multiple scattering analysis is of great significance for detecting the characteristics of cloud particles,and the feasibility of detecting the characteristics of cloud particles by the designed laser radar system is verified.