摆镜图像稳定控制系统在NVST中的应用研究

The Study on the Application of the Stabilized Control System for the Tip-tilt Mirror Image in NVST

由于1 m太阳望远镜采用圆顶移开并远离望远镜的敞开式观测模式,使得望远镜跟踪系统受风的影响较大,表现为观测时图像随风出现较大幅度的低频抖动。为解决这一问题,首先根据望远镜现有的光学系统和风载影响下焦面图像抖动的特点,在氧化钛高分辨率成像通道中设计了基于二维摆镜的图像稳定系统。然后根据二维摆镜系统的实测特性,建立系统的传递函数,设计控制器。深入的数值模拟分析和实验表明,在五到六级风作用的情况下,摆镜图像稳定系统工作在25 Hz就能将1 m太阳望远镜焦面图像抖动的均方根值控制在0.5″以内,表明二维摆镜的图像稳定系统可以稳定望远镜由随机风载引起的图像抖动。

Because the dome of the New Vacuum Solar Telescope （NVST） is moved away from the telescope when it is at the operation, the tracking system of the telescope is largely affected by the wind. This effect manifests for the image jitter greatly in the low-frequency wind. In order to solve this problem, the design of an image stabilization system based on the two-dimensiontip-tih mirror in the present TiO high-resolution image channel is made. This designation is based on the existing optical system of the telescope and the characteristics of the focal plane image jitter under the effects of the wind. According to the measured properties for the two-dimension tip-tilt mirror system, we established the transfer function of the system, and designed the controller. After in-depth analysis of the numerical simulation and the experiments, it is showed that in the five to six level wind effects, it be able to control the RMS value of the image jitter for the NVST below 0. 5 arcsec when the Tip-tih mirror image stabilization systems operating at the 25Hz. This indicates that the tip-tilt mirror image stabilization system can compensate the image jitter of the telescope caused by the wind.