基于结构函数的大口径望远镜中频误差分配研究

发布时间：2018-07-04 09:59

本文选题：大口径望远镜 + 标准化点源敏感性　；参考：《光学精密工程》2017年02期

【摘要】：为了更好地对于大口径望远镜中频误差进行评价与分配,本文引入了结构函数来进行研究。本文首先对于结构函数的基本性质进行了推导,并与传统的误差均方根(RMS)进行比较,表明了其表征不同尺度误差的能力。之后分析了系统波前在不同的评价尺度下的统计特性差异,得出在较小尺度下,系统的误差分布可以较好的服从正态分布,而随着尺度的增加(如大于100mm)会逐渐偏离正态分布的结论。然后根据结构函数的基本性质,提出了一种可以同时考虑诸多误差源的大口径望远镜中频误差分配方法。结合美国三十米望远镜(TMT)团队所提出的标准化点源敏感性(normalized Point Source Sensitivity,PSSn),建立起了由结构函数到标准化点源敏感性的换算关系,通过此方法来进行误差分配指标间的交叉验证以及与其他单元技术之间的对接。最后,根据本文所提出的方法,对于某大口径望远镜的主镜系统进行了误差分配,得到在大尺度均方根为25nm,粗糙度为1nm,中频尺度为250mm,大气相干长度为0.4m(检测环境)的要求下,该系统的结构函数满足要求,同时由要求结构函数所计算得到的PSSn=0.999 6大于由镜面数据直接得到的PSSn=0.999 5,同样满足要求。
[Abstract]:In order to evaluate and distribute the intermediate frequency error of large aperture telescope better, the structure function is introduced in this paper. In this paper, the basic properties of the structure function are first deduced, and compared with the traditional error mean square root (RMS), which shows its ability to represent the errors of different scales. After analyzing the difference of the statistical characteristics of the system wavefront under different evaluation scales, it is concluded that the error distribution of the system can be well applied to normal distribution at a smaller scale. However, with the increase of scale (such as greater than 100mm), the conclusion of normal distribution will be gradually deviated. Then, according to the basic properties of the structure function, a method of intermediate frequency error allocation for large aperture telescope is proposed, which can consider many error sources at the same time. Based on the normalized Point Source sensitivity (PSSN) proposed by the United States 30-meter Telescope (TMT) team, a conversion relationship from structural function to normalized point source sensitivity is established. This method is used to cross-verify the error allocation index and to connect with other unit techniques. Finally, according to the method proposed in this paper, the error distribution of the primary mirror system of a large aperture telescope is carried out. Under the requirements of large scale root-mean-square (RMS) of 25nm, roughness of 1nm, intermediate frequency scale of 250mm and atmospheric coherence length of 0.4m (detection environment), The structure function of the system meets the requirements, and the PSSnN 0.999 6 calculated by the required structure function is larger than the PSSnN 0.999 5 obtained directly from the mirror data, which also meets the requirements.
【作者单位】：中国科学院长春光学精密机械与物理研究所;中国科学院大学;
【基金】：国家自然科学基金资助项目(No.11403022)
【分类号】：TH751

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