基于长脉冲光源的钠信标回光特性实验研究

采用与信标发射接收系统参数匹配的长脉冲光源,可在脉冲回光时间内产生较亮星等的钠信标,既有利于提高信标探测的信噪比,也有利于实现自适应光学系统的高频闭环校正.基于450 mm直径望远镜和大能量长脉冲光源,开展了钠信标探测实验,得到了长脉冲光源产生的钠信标回光特性.通过CCD和光电倍增管,采集得到了不同发射能量、出射偏振态下的回光强度,并获得了最大强度为15万光子/m2/pulse的回光,对应脉冲回光时间内约4.1等星的亮度.分析推算了实验条件下钠原子的柱密度.实验全过程未出现明显的饱和现象,验证了采用长脉冲钠信标光源避免饱和效应、得到高亮度钠信标的可行性.

Experimental study on backscattering characteristics of sodium beacon based on a long pulse laser

A sodium beacon with bright magnitude can be obtained during backscattering time, by utilizing a long pulse laser with parameters matched with a sending and receiving beacon system. This is helpful to get high SNR in detecting beacon, and to achieve a closed-loop correction at high frequency. Based on a 450 mm telescope and a high-energy long pulse laser, the detection experiment of sodium beacon was carried out, and the backscattering characteristics of sodium beacon were obtained. The intensity data of backscattering light with different launching energy and polarization were collected by CCD and PMT. As high as ～15,000 photons/m²·pulse^-1 of backscattering light was detected, and the brightness is close to 4.1 magnitudes during backscattering time. The column density in experiment was derived from analyzing and calculating experimental data. No saturation phenomenon was observed during the whole experimental process. And the feasibility to avoid saturation is verified and a bright sodium beacon is obtained by utilizing a long pulse laser.