| Author Name | Affiliation | | Qichang An | Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China
Graduate University of Chinese Academy of Sciences, Beijing 100039, China | | Jingxu Zhang | Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China | | Fei Yang | Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China | | Hongchao Zhao | Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, China |
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| Abstract: |
| Giant Steerable Science Mirror (GSSM) is the tertiary mirror of the Thirty Meter Telescope (TMT). To evaluate the performance of the GSSM under the mechanical vibration, the Normalized Point Source Sensitivity (PSSn) is used to understand and characterize the optical performance degradation. First and foremost, the definition of the PSSn is shown and the calculation procedure of the PSSn at the work condition where the telescope aberration is much smaller than seeing is presented to reveal the relationship between PSSn and seeing. Then, the optical degradation due to vibration is achieved by the two methods: one is the statistics moment for the arbitrary froms of vibration and other one is spectrum method for wind load. After the theoretical presence, the simulation is processed. The multi-axis-accelerometers are used to achieve the motion of the mirror. After integrated to displacement signal, the measured signal is applied to the mathematical model of the GSSM and the optical performance degradation under certain mechanical vibration can be achieved. The PSSN flows from 0.996 to 0.994 under some dynamic vibration. And then, the wind load is applied to the mathematical model using spectrum method with the PSSN flows from 0.996 to 0.991. This paper can help the system engineers to predict the performance of the GSSM in various work condition. What is more, PSSn is able to be combined just by simple multiplication, so the optical performance degradation can be easily co-considered with other error sources. |
| Key words: Thirty Meter Telescope Normalized Point Source Sensitivity optical transfer function mechanical vibration |
| DOI：10.11916/j.issn.1005-9113.15334 |
| Clc Number:TH751 |
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| Descriptions in Chinese: |
| 基于归一化点源敏感性的GSSM振动影响评价 安其昌1,2,张景旭1,杨飞1,赵宏超1 （1.中国科学院长春光学精密机械与物理研究所，长春 130033; 2.中国科学院大学，北京 100039） 创新点说明：1）深入研究了振动对于GSSM光学中继作用的影响，并建立与PSSn的联系； 2）引入统计矩的方法获得GSSM在任意可测载荷下的光学传递函数； 3）引入功率谱的方法获得GSSM在统计载荷下的光学传递函数。 中文摘要：巨型可控科学反射镜系统（GSSM）是国际合作项目30 m望远镜（TMT）的三镜。为全面研究GSSM 在振动下的光学传递能力的降低，本文引入了归一化点源敏感性（PSSn）以实现在整个频域上全面地评价系统所受到的影响。首先，介绍了PSSn的基本概念和定义，推导了在大气视宁占主导情况下系统PSSn的计算方法，为GSSM的概念设计与误差估计提供理论依据。之后，对在可测的任意载荷及符合统计规律的载荷（如风载）这两类载荷下的系统光学传递函数的计算方法进行了研究。在任意载荷下使用的是所测得振动的高阶统计矩，通过数值的方法来获得系统的光学传递函数；而对于符合统计规律的载荷，使用功率谱来进行分析。通过实测结合仿真得到GSSM在上述两种情况下PSSn从0.996分别下降到0.994和0.991。本文的研究，建立了GSSM所受振动与PSSn之间的关系，可以为系统工程师在进行GSSM以及TMT的误差分配过程中提供参考。同时由于PSSn良好的合成特性，可以结合其他误差项一起考虑。 关键词：三十米望远镜；标准化点源敏感性；光学传递函数；机械振动 |
