Wang Chongchong, Hu Lifa, Wang Yukun, Wang Shaoxin, Mu Quanquan, Li Dayu, Cao Zhaoliang, Yang Chengliang, Xu Huanyu, Xuan Li
Appl Opt. 2015 Apr 10;54(11):3383-8. doi: 10.1364/AO.54.003383.
The time delay engendered by wavefront sampling and data processing inevitability exists in almost all the wavefront sensor (WFS) based adaptive optics (AO) systems. Also, when WFS is used for tip-tilt aberration detection, the time delay significantly reduces the tip-tilt correction performance of the AO system. In this paper, we focus on researching time delay in a tip-tilt (TT) control system and introduce a predicted signal compensation method (PSCM) to compensate the time delay by modifying the WFS detected signals. Based on a precise model of a TT dynamic control system, the detection delay of TT corrections included in a WFS detected signal can be compensated. Experiments are conducted in the lab: the pure integrator (I), proportional and integral (PI) wavefront TT controllers, and these controllers with PSCM are compared to test the efficiency of the PSCM for TT corrections. For the PI controller, the rejection bandwidth increases from 52 to 62 Hz by using PCSM; meanwhile, the open-loop phase margin increases from 45 to 60 deg. In addition, astronomical observation results are also given based on the PI wavefront TT controller. The PSCM improves the Strehl ratio by a factor of 1.3. The new method is proven to improve the AO system closed-loop performance not only for increasing the closed-loop rejection bandwidth but also in favor of the error attenuation at low frequency. Furthermore, the method does not introduce more noise to the system.
由波前采样和数据处理产生的时间延迟几乎不可避免地存在于所有基于波前传感器（WFS）的自适应光学（AO）系统中。此外，当使用波前传感器进行倾斜像差检测时，时间延迟会显著降低自适应光学系统的倾斜校正性能。在本文中，我们专注于研究倾斜（TT）控制系统中的时间延迟，并引入一种预测信号补偿方法（PSCM），通过修改波前传感器检测到的信号来补偿时间延迟。基于倾斜动态控制系统的精确模型，可以补偿波前传感器检测信号中包含的倾斜校正检测延迟。在实验室中进行了实验：比较了纯积分器（I）、比例积分（PI）波前倾斜控制器以及带有预测信号补偿方法的这些控制器，以测试预测信号补偿方法对倾斜校正的效率。对于比例积分控制器，通过使用预测信号补偿方法，抑制带宽从52赫兹增加到62赫兹；同时，开环相位裕度从45度增加到60度。此外，还给出了基于比例积分波前倾斜控制器的天文观测结果。预测信号补偿方法将斯特列尔比提高了1.3倍。新方法被证明不仅通过增加闭环抑制带宽，而且有利于低频误差衰减来提高自适应光学系统的闭环性能。此外，该方法不会给系统引入更多噪声。
