Technologies Of Dual-wavelength High Altitude Lidar And Daytime Observation For Na Channel

The detection and investigation of atmosphere in the range of 30～110km are of greatimportant to the application of atmospheric physics, high-tech and national defense. However,research into this range of atmosphere is not as active as that in other ranges of atmospherebecause there is no effective detection instrument.The situation has changed much since the invention of Rayleigh scattering lidar andSodium fluorescence lidar. Since 1980's, many countries all over the word have established thosetwo kinds of lidars, and have applied them to researches into atmosphere of this range in theircountries.In 1996, we developed the first Rayleigh and Sodium lidars in our county, and conductedthe detections and obtained the observation results by using these two lidars. As these two lidarsare different in both mechanisms and laser wavelengths, the lidar could only work in oneconfiguration, that is, either Rayleigh scattering or Sodium fluorescence. In order to make thelidar working in both Rayleigh scattering and Sodium fluorescence mechanisms simultaneously,we have refined the lidar by using some key techniques and have gotten success. We called therefined lidar the dual-wavelength high altitude lidar.As the return signal of the high altitude lidar is extremely weak, the probability of receivingone return photon in our sampling gate is about 10%. In order to realize the daytime workingability, the strong background light from the sun has to be eliminated. We have used the SodiumFaraday Atomic Filter technology to realize the daytime working ability for the sodiumfluorescence channel of the dual-wavelength high altitude lidar, and have got about 50 hourscontinuous observation result.The thesis is mainly consists of two parts: the dual-wavelength lidar technology and thedaytime observation technology for sodium fluorescence channel.The dual-wavelength high altitude lidar is our own-patented technology. By using thetechnique of dual SHG, dual optical fiber and high altitude overlap scheme, Rayleigh scatteringand Sodium fluorescence mechanisms were merged into one lidar. In this way, a large span ofatmosphere, ranging from 30 to 110km, can be detected by one lidar.The daytime sodium fluorescence technique is similar to that pioneered by the lidar groupof Colorado State University, USA. The key technique we used is also the Sodium FaradayAtomic Filter. The principle, development of the atomic filter and the corresponding lidarreceiver are also given in the thesis.