自参考干涉波前传感器中针孔直径对闭环自适应光学系统校正精度的影响

使用自参考干涉波前传感器(SRIWFS)进行波前的绝对测量时,为了获得近似平面波前的参考波,针孔直径应该不大于无畸变光学系统艾里斑直径(d_A)的一半,然而这必将导致光能利用率的严重下降.为了最大程度地提高光能利用率并改善干涉条纹的对比度,研究了SRIWFS应用于闭环校正中时所允许的最大针孔直径,这将在闭环开始阶段尤为重要.数值模拟和实验表明,直径不大于1.5d_A的针孔可以获得满意的校正结果,校正后远场斯特列尔比高于80％;同时光能 关键词： 自适应光学 自参考干涉波前传感器 针孔直径 闭环校正

Effect of pinhole diameter on correction accuracy of closed-loop adaptive optics system using self-referencing interferometer wavefront sensor

When the self-referencing interferometer wavefront sensor (SRIWFS) is applied to the absolute measurement of wavefront phase, the pinhole diameter should be less than half the Airy-disk diameter (d_A) produced by an unaberrated optic so as to obtain a good approximation to a reference plane wave. In this way, however, the intensity transmission is also greatly reduced. To increase the intensity transmission as much as possible and improve the fringe contrast especially in the beginning of closed-loop correction, the maximal pinhole diameter allowed in the closed-loop correction with using SRIWFS is studied. Computer simulation and experiment demonstrate that a pinhole with not greater than 1.5d_A can obtain a satisfied correction result and the Strehl ratio after correction is greater than 80%. Additionally, for a plane wavefront the intensity transmission will be increased from 63% to 90% as the pinhole diameter increases from 0.5d_A to 1.5d_A.