Design And Implementation Of Control And Data Acquired Systems For Lidar Systems

Detection and understanding the physical and chemical processes of atmospheric environment in the earth, is crucial to the aerospace, defense and security of the earth’s biosphere. Because laser wavelength is shorter than radio of small3-5magnitude, energy of single photon is so high that it can interact with a variety of molecules/atoms in the atmosphere. Lidar has high sensitivity to detect only a few atoms per cubic centimeter of atmospheric trace constituents from ground to near a hundred kilometers of. Due to ultrashort pulse and very narrow beam, lidar has a high spatial and temporal resolution. Because of these excellent properties, lidar becomes the mainstream of the exploration of the upper atmosphere as remote sensing equipment. In the past ten years, Wuhan University researchers successfully developed7different large lidar system which have ability to measure basic parameters and metal composition from-0to100km altitude atmosphere, including the world’s only Fe-Na-Ca/Fe-Na-Ca+co-volume observation system and the world second wholly water spectrum Raman lidar. Consists of7sets of lidr co-volume optical detection platform will help China exploration of the upper atmosphere research moving to the international frontier, and was awarded as Chinese ten major technologies by Science and Technology Review in2011. Our lidar observation leads to some new phenomena, with providing the data basis for the study of space and earth environment of China. This paper introduces the system design and implementation techniques of our lidar systems. The main research work is as follows:1:The design and implementation of the control and data acquisition systemsof metal layer lidarshave been achieved. We found that the metal layer is composed of Na, Fe, Ca and other metal atom nested form. The relationship between Fe-Na with delicate nested structures does not change with time, especially the lower boundary of Fe and Na always follow the same motion and shows fine layering. Through the first metal layer co-volume observation with three lidar systems in the international, we found that sporadic metal layer is usually composed of a mixture of several metal neutral atoms and ions with high accuracy and resolution, and three different kinds of metal atom or ion density increases in overlap height range and exhibit the same movement tendency. These results show that the metal layer is the product of the same source process. The America lidar research groups (Colorado lidar group, Miami University, Arecibo Observatory) pursue our work, and their observations in two different latitude areas have showed similar results with us. Our works raise strong doubts about basic assumptions of existed metal layer theory, and may give new knowledge of metal layer and bring about a change of understanding the basic physical process in the mesopause region.2:With the designed optical device based the Fabry Perot etalon, the continuous over48hours observation of sodium lidar has been achieved. The signal to background ratio of the data at12noon is about1/5. In this observation, column density and width of sodium metal layers presents semidiurnal oscillation, and we also found a case of sporadic layer which its peak height is less than90km.3:We extended the single channel Raman lidar data acquisition system to a32channel synchronous data acquisition system, to achieve the second full water spectrum water Raman lidar in the world. We found that water Raman spectral shape is universal under clear atmospheric condition which can act as different weather conditions to identify other phases (liquid and ice water spectrum) background. We first measured Raman spectrum of atmospheric liquid water and found that:(1) the atmospheric liquid water Raman spectrum of knowledge we knew before is not consistent with the existing water Raman spectrum, which is expected to arouse the new theoretical and observational studies;(2) the spectral position measuring atmospheric liquid water should not be404nm, but the shorter wavelength. This provides the observation basis of the atmospheric liquid water Raman spectral.