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自由信道的大气透射率对自由空间光通信系统的设计和应用具有重要的价值,经典的大气透射率测量方法的精度水平已不能满足实际需求。结合实际应用中激光器光束能量的高斯分布特性和存在于大气信道中的湍流影响特性,对经典的大气透射率测量方法进行了改进,提出了大气透射率精确测量的实验方案。对上海和青海的多条自由空间信道的大气透射率采用经典方法与新提出方法分别进行了测量,得到的结果之间存在差异。发现青海的大气透射率很高,但是大气湍流相对严重,而上海的大气情况正好相反。分析和实验数据还表明经过长距离湍流信道后光斑扩展严重。
Atmospheric transmittance of free channel is of great value to the design and application of free space optical communication system. The accuracy of classical atmospheric transmittance measurement method can not meet the actual needs. Based on the Gaussian distribution of laser beam energy and the influence of turbulence existing in atmospheric channel, the classical method of measuring atmospheric transmittance is improved, and the experimental scheme of accurate measurement of atmospheric transmittance is proposed. The atmospheric transmittance of many free-space channels in Shanghai and Qinghai were measured respectively by the classical method and the new proposed method, and the results were different. It is found that the atmospheric transmittance of Qinghai is very high, but the atmospheric turbulence is relatively serious, while the atmosphere in Shanghai is just the opposite. Analytical and experimental data also show that flare spreads significantly over long-haul turbulent channels.