Directly Lidar Research

Direct detection wind lidar is currently available instrument for windfield measurement in the clear atmosphere. In order to research the change of climate, predict weather numerically and avoidshearing wind effectively to improve flight safety, reliable and accurate wind data are badly needed. So there is important meaning to measure wind real time.This paper deals with the basic concepts of DWL. DWL is an active remote sensing instrument that uses aerosol and molecular backscatter to measure wind. DWL instrument concepts can be divided into two main categories: Direct detection and coherent detection. The direct detection method, which use high-resolution optical devices such as a Fabry-Perot etalons, detects the Doppler shift directly from spectrum of light backscattered from atmospheric air molecules and aerosols.The edge technique is a direct detection method for measuring Doppler shift of an atmospheric backscattered signal from a pulsed laser by differential measurement of atmospheric echo and the outgoing laser pulse. The double-edge technique is a variation of the edge technique. It has the same basic advantages as the edge technique but with new capabilities. It improves the measurement accuracy and allows the Rayleigh and aerosol components of the signal to be separated.Optimization of the operating parameters of Fabry-Perot interferometers for the direct detection Doppler wind lidar based on double-edge technique is considered in detail.This disseratation mainly studies the frequency discrimination system of winds measurement lidar. The double-edge detection theory for scattered signal of aerosol in lower atmosphere is deduced, the interaction of atmosphere and the laser beam during the transmission and all kinds of disturbing signals of the return signal are analyzed here. I simulate the return signal and the transmission function of F-P,choose the appropriate parameter of F-P based on their influence of the sensitivity of the system, and simulate the process of frequency discrimination.A feedback technique to locate the laser frequency on the steep edge of the F-P is also presented, At last, I analyze the response, sensitivity and errors of the system according to the simulant data.The simulation of the system shows the possibility of the design.