孔径匹配对中继镜系统上行传输影响的模拟与分析

Simulation and analysis on effect of aperture matching on uplink propagation for relay mirror systems

利用激光大气传输四维程序,建立了双望远镜中继镜系统上行传输模型,研究了孔径匹配对中继镜系统上行传输的影响。选择去除畸变相位后接收光场的远场峰值功率密度作为中继镜系统上行传输的性能指标,通过光束在真空中传输的计算,得到了接收口径一定时不同发射口径对应的最优发射焦距,并对不同发射功率激光在大气中上行传输的情况进行了模拟计算。结果表明,当接收孔径一定时,随着发射孔径的增大,最优发射焦距减小;增大发射孔径,可以增大临界发射功率;当发射功率较小时,在一定发射口径范围内,发射口径的变化对中继镜系统上行传输的性能指标影响不大,当发射功率较大时,增大发射口径可以有效提高中继镜系统上行传输的性能指标。

The model for uplink propagation for the relay mirror systems was established, and the effect of aperture matching on uplink propagation for relay mirror systems was simulated and analyzed by the 4-D code for laser propagation in atmosphere. The far-field peak power density of the received beam whose distorted phase was completely removed was selected as the evaluation function of the uplink propagation process. The optimal focal lengths of different transmitting apertures were picked out based on the calcula- tion in vacuum, and the uplink propagation in the atmosphere for different transmitting apertures with their respective optimal focal length was simulated. Results show that with a certain receiver aperture, the opti- mal focal length decreases while the transmitter diameter increases. The critical launching power increases with the increase of transmitter diameter. When the launching power is small, the change in transmitter di- ameter imposes little effect on the performance, but when the launching power is high enough, performance of the relay mirror system is improved significantly with the increase of transmitter diameter.