Development Of A Compact Mie Lidar System For Atmospheric Aerosol Detection

The atmospheric aerosol, including dusts, smokes and cirrus cloud is mainly distributed in the troposphere and is one of the important atmospheric parameters, which plays a significant role in study of atmospheric transmission of laser, weather forecast, atmospheric environmental research as well. The lidar has been one of the important tools for measuring optical character of atmospheric aerosols because of its high space-time resolution, high accuracy and special merits of being able to interact with the little aerosols in the atmosphere.Mie lidar is an effective tool for detecting the density distribution of dusts, smokes, etc. In this paper, a compact Mie lidar system is demonstrated for measuring the optical properties of aerosols and atmospheric horizontal visibility below 3km in the troposphere. A LD pumped Micro pulse laser at 532nm with eye-safety characteristic is employed as a transmitter; a Cassegrain astronomical telescope with 254mm aperture, 0.4mrad angle of field and is selected as optical receiver and a narrowband interference filter is also applied to reduce the solar background precisely for daytime measurement. On the mechanical design, the transmitter and receiver are designed to be an integrated module, similarly, the iris and interference filter which are used to block the solar background are fitted together in the receiver in order to improve the stability of this system and to achieve a compactness design.With the scanning control part of the system, serial communication is used for PC and MCU data transmission. Two step motors controlled by MCU, are used to drive transmitter-receiver module for achieving an azimuth or elevation angle motion. This lidar system has the advantages of small frame, compact structure, eye-safety and third dimension scanning.Experimental observation was taken at Xi'an for profiling the optical properties of atmospheric aerosols and horizontal visibility. The experimental result shows that this compact Mie lidar system has capable of measuring the atmospheric aerosols with an error of less than 10% up to a range of 6km at nighttime. The atmospheric horizontal visibility versus date of Xi'an city in winter is obtained, and its results show that the lidar data is close to practical weather condition reported by weather bureau of the location. All of these prove that this system has met the preliminary requirement of design.