自适应光学技术在通信波段对大气湍流的校正

Correction of atmospheric turbulence by adaptive optics in waveband of free-space coherent laser communication

针对大气湍流引起的激光光强、相位和传输方向的随机变化对大气激光通信质量的影响,开展了用自适应光学(AO)技术校正大气湍流影响的研究。定量分析了自适应光学技术在通信波段校正大气湍流的效果。利用中国科学院光电技术研究所研制的安装在云南丽江高美谷观测站的1.8m望远镜和127单元AO系统,在1 550nm通信波段对不同高度角的恒星进行了大气湍流校正实验。通过采集校正后的恒星图像,分析了校正后的斯特勒尔比,同时记录下当时的大气相干长度,由此得到了在不同大气湍流条件下的校正效果。实验表明,当大气湍流强度D/r0(1 550nm)小于6.5时,校正后的波面RMS值可以小于1rad,即在中弱大气湍流条件下,该AO系统可以有效地对大气湍流进行校正。

In consideration of effect of intensity scintillation, phase distortion and transmission direc- tion changes caused by atmospheric turbulence on communication links, this paper explores the cor- rection technology of the atmospheric turbulence by the adaptive optics （AO）. The correction effects of the AO on atmospheric turbulence in the waveband of free-space communication was analyzed quan- titatively. A field experiment to observe the star with different altitude angles in the 1 550 nm wave- band was performed with a 1.8 m telescope mounted on Yunnan and the 127-actuators AO system de- veloped by the Institute of Optics and Electronics, Chinese Academy of Sciences. The Strehl ratio and the atmospheric coherent length were recorded for the observation of each star. The experiment re- sults show that when the atmospheric turbulence intensity D/ro （1 550 nm） is less than 6.5, the wave- front error will be less than 1 rad after correction by the AO. It concludes that the AO is able to over- come the effect of the atmospheric turbulence on the required quality of free-space coherent laser com-munication under weak and moderate turbulence conditions.