抚仙湖太阳观测和研究基地知识库

大气湍流严重干扰地基天文观测和空间目标观测。随着多层共轭自适应光学(MCAO)等技术的发展,可以有效的改善湍流大气的干扰。为了MCAO的设计和性能优化,需要对址点的大气湍流轮廓线进行测量。目前湍流轮廓线测量方法有很多种,其中PML、S-DIMM+等基于面源目标像的相对运动方差或协方差统计反演的方法,具有分层分辨率高、测量精度高等优点。反演的线性方程组经过离散化获得,离散化误差导致观测视场不能太大,以PML为例,只能达到100角秒左右。较小的视场使方程数目受限,导致湍流轮廓线反演结果受运动方差或协方差测量误差的影响。本文以PML方法为研究实例,提出了分层积分系数矩阵方法,该方法明显改善了离散化误差,大幅增加了观测视场范围,降低协方差误差对测量结果的影响,提高了湍流轮廓线反演精度。数值模拟结果表明,分层积分系数矩阵PML方法,其视场可达到400角秒,测量误差也大幅度降低。

The multi-conjugate adaptive optics(MCAO)can effectively reduce the disturbance of turbulent atmosphere.For the design and performance optimization of MCAO technology,it is necessary to measure the atmospheric turbulence profiles of the site.The inversion linear equations of the methods based on differential image motion variance or covariance of extended object are obtained through discretization.The discretization error causes the effective field of view(FOV)not to be very wide.A small FOV limits the number of equations,resulting in turbulence profile inversion results being affected by motion variance or covariance measurement errors.In this paper,taking the PML method as an example,we propose a layer integral coefficient matrix method.This method obviously reduces the discretization error,greatly improves the range of observation FOV,reduces the influence of the covariance error on the measurement results,and improves the accuracy of the turbulence profile inversion.The simulation results show that the FOV of the PML method using layer integral coefficient matrix can reach 400″,and the measurement error is also greatly reduced.