反射式日冕仪的设计与杂散光分析

	反射式日冕仪的设计与杂散光分析
	李达
学位类型	博士
导师	陈波
	2014-07
学位授予单位	中国科学院大学
学位专业	光学
摘要	日冕是太阳大气的最外层，从过渡区顶部向外延伸到几个太阳半径，甚至更远的区域。日冕活动对地球周围空间环境变化影响重大，是空间天气预报的关键部分之一，对日冕的观测研究对太阳物理学、人类活动乃至对国家经济生活和太阳物理学研究具有重要意义。 Lyman-alpha(拉曼阿尔法)辐射在太阳物理学和日冕物理学中占据了非常重要的地位，作为色球层光谱的主要成分，可以通过拉曼阿尔法光谱的观测分析出色球层的主要结构。对于日冕成像最大的困难是：日冕的亮度相对太阳光球层和色球场而言极为微弱，因此日冕仪的设计需要重点考虑日面照射到仪器上所引起的入瞳边缘衍射和主镜面自身散射的问题。本文首先介绍了日冕仪的发展历史和透射式日冕仪的基本原理，针对外遮光日冕仪的外部遮光器圆盘遮挡效果和边缘衍射光线进行了理论性计算。针对日冕仪反射式结构，提出了入瞳位置假设，并在轴上近似条件下计算了主物镜，次镜和成像反射镜的位置，进一步的计算和讨论了全反射式日冕仪在轴上理想成像近似时，入瞳成像即里奥光阑的位置是场镜和成像镜的焦距与间距的函数；在相同的近似条件下，得到了里奥光阑的尺寸计算公式，是关于三个物镜的焦距和间距的函数，这对以后的全反射日冕仪设计一定的参考价值。设计了口径为40mm、焦距为590mm的全反射式拉曼阿尔法日冕仪，传递函数接近衍射极限。利用光学分析软件建模分析了杂光情况：像面上接收入瞳边缘衍射能量约为入射能量的6.8×10-9，提出主镜面的加工要求。设计并装调一套球面反射式日冕仪实验装置，建立光学分析仿真模型，采用点源透射率PST曲线的方法测量了此日冕仪的杂散光水平，通过对比实际像面上子午面的杂光分布曲线，验证了仿真模型的有效性。最后对比了计算和测量光学系统杂散光的方法，根据杂光系数和PST函数关系式计算得到反射式日冕仪实验装置的杂光系数为0.278。
其他摘要	The corona is the outermost layers of the solar atmosphere, extending outward from the top transition region to several radius of the sun, and even farther. Solar corona observation is a key part of the space weather forecast，and has great significance to the national economy and the solar physics research. Lyman - Alpha radiation, as the main components of the chromospheres spectrum occupies very important position in solar physics and corona physics, by Lyman Alpha spectrum analysis of the observation can get main structure of solar chromospheres. For corona imaging, the most difficulty is: the brightness of the corona is too small, thus coronagraph design need serious consideration about the instrument pupil edge diffraction and scattering caused by primary mirror, at the same time take the initiative to increase the internal structure such as shielding and Lyot stop. This article introduces the history of coronagraph, according to Lyot’ s corona design criterion, introduces the basic principle of transmission solar coronagraph with external occulter. There is a theoretical calculation about block effect and edge diffraction of external disk, and a calculation about ghost position and strength made by objective of multiple reflections which shows that a appropriate change position of the Lyot spot can improve the effect of shade.There is a further introduction about reflection solar coronagraph and put forward a hypothesis about the pupil position, and the approximate calculation of the position of the mirrors under a coaxial approximation, calculation the position of the aperture which is a function about the focal lengths of field mirror and third mirror, has nothing to do with the focal length of objective mirror. Under the same approximation condition, the size formula of the Lyot aperture which is a function of three mirrors’ focal lengths and distance is calculated. The calculations have a guiding effect for reflection coronagraph design. In this paper, a coronagraph which diameter is 40 mm, the focal length is 590 mm total reflection Lyman alpha coronagraph is been designed, with a transfer function is close to the diffraction limitation. Analyze the stray light of the coronagraph via a model build by software named as Trace Pro. The edge diffraction energy from the pupil received at the image plant is about 6.8 x 10-6. According an empirical formula, the object mirror‘s surface root mean square (RMS) roughness values should be below 0.2 nm. A new sphere reflection coronagraph experimental device is designed and manufactured, which spatial resolution of the system is 17.96 per millimeter. The stray light distribution curves are got in meridional direction of the simulation model by using the Trace pro software to build the coronagraph simulation model, and compared with experimental data. The compared result indicates the simulation model is reasonable. The coronagraph system stray light point source transmittance curves are obtained and the corresponding veiling glare index of the device is 0.278.
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/41425
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	李达. 反射式日冕仪的设计与杂散光分析[D]. 中国科学院大学,2014.

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