应用天文研究组知识库

激光导引星波前倾斜测量问题是限制自适应光学技术在天文领域广泛应用的关键问题之一。测量并改正激光上行到达角起伏是解决这一问题的有效方法。提出一种基于统计平均算法而不依赖自然导引星和辅助望远镜的测量方法,可以有效地测量出激光上行到达角起伏。利用具有子孔径阵列的哈特曼波前传感器对激光信标进行探测,选择部分子孔径进行倾斜量的统计平均以获得激光上行到达角起伏。仿真了统计平均算法的误差随子孔径数量的变化关系。结果表明,最小算法误差相对于望远镜全口径倾斜误差的下降比例与大气Fried常数无关,而与望远镜口径有关。望远镜口径越大,算法误差相对于全口径倾斜误差下降越多。当望远镜口径为10m时,最小算法误差下降为望远镜全口径倾斜误差的33%。

Tip-tilt indetermination with Laser Guide Star(LGS) is one of the important factors to limit the sky coverage for laser guide star adaptive optics(LGS-AO). Measuring and correcting the angle-of-arrival fluctuations of laser uplink is an effective method to solve this problem. This paper proposed a method to measure angle-of-arrival fluctuations of uplink laser, which without natural guide star and auxiliary telescope. The mean idea of that method is that LGS is detected by Shack-Hartmann wave front sensing and the laser uplink angle-of-arrival fluctuations is reconstructed by the data from selected sub-apertures. In this paper, the relationship between the error of the optimal algorithm and the number of selected sub-apertures is simulated. The results show that the decline ratio of the minimum algorithm error relative to the telescope's full-aperture tilt error is not related to r0, but is related to the telescope's aperture. The larger the telescope aperture is, the more the algorithm error decreases. When the telescope diameter is 10m, the minimum algorithm error drops to 33% of the telescop's full diameter tilt error.