大视场日冕仪关键技术研究

	大视场日冕仪关键技术研究
	孙明哲
学位类型	博士
导师	卢振武
	2014-07
学位授予单位	中国科学院大学
学位专业	光学
摘要	日冕仪是观测日冕和日冕物质抛射现象的仪器。观测日冕和日冕物质抛射现象可以研究太阳磁场对地球的影响，并可以对影响地球及日地空间的灾害性空间天气进行预警。本论文讲述的大视场日冕仪是国际上首次设计的中心遮拦的大视场日冕仪，国际上目前中心遮拦的日冕仪最大视场为30R⊙（R⊙为太阳半径），大视场日冕仪在近地点的视场为72R⊙，在远地点的视场达到215R⊙。应用大视场日冕仪可以对从太阳到地球范围内的日冕及日冕物质抛射现象进行观测。本论文借鉴国际上日冕仪研制的经验，对日冕仪进行设计。本论文研制的大视场日冕仪光学系统主要参数为：视场为以太阳为中心±20度，像素分辨率为1.2 arcmin，像素大小为13.5μm，波段为630nm～730nm，系统总长为896mm，其中光学系统总长为356mm，工作F数为5，像方焦距为40mm，传递函数大于0.65。本论文研制的日冕仪视场远大于国际上现有的日冕仪，而视场的增大大大增加了日冕仪对杂散光抑制的要求。为此对日冕仪的杂散光抑制进行了深入研究。首先从理论上对日冕仪外掩体和外窗口的衍射杂散光水平进行了计算。其次，对大视场日冕仪的衍射杂散光和散射杂散光分别进行建模，得到理论上杂散光的量级。衍射杂散光建模主要应用分数傅立叶变换理论和菲涅耳——基尔霍夫衍射积分理论，散射杂散光建模主要应用ABC模型，对表面粗糙度和灰尘污染物造成的杂散光进行计算。第三，本文对大视场日冕仪所有可能产生的杂散光进行分级，并对其分别进行抑制。其中一级为太阳直射光；二级为外掩体和外窗口的衍射光；三级为物镜口径的衍射光，物镜表面粗糙度和灰尘造成的散射光，拒热镜表面散射的杂散光和物镜表面多次反射造成杂散光。最后对日冕仪整机杂散光进行检测，总杂散光抑制水平达到10-11B⊙量级（B⊙为太阳平均亮度）。
其他摘要	Coronagraph is an instrument observing the corona and coronal mass ejections. Observations of the corona and coronal mass ejections help to study the effects of the sun's magnetic field on the earth. In the mean while, they can monitor the severe space weather events which affecting the earth and the solar-terrestrial space. In this paper, the Large Field of View Coronagraph is designed for the first time which is central occulted and with large field of view. At present, the largest field of view of the coronagraph which is central occulted is 30 R⊙(R⊙ is the sun radius). The field of view of the Large Field of View Coronagraph is 72 R⊙ in the perigee, and 215 R⊙ in the apogee. This Coronagraph can monitor the corona from the sun to the earth. This paper learns from the international coronagraph manufacture experience. For the Large Field of View Coronagraph in this paper, the main parameters of the optical system are as follows: the field of view is ±20 degrees; the pixel resolution is 1.2 arcmin; the pixel size is 13.5 μm; the wavelength is from 630 nm to 730 nm; the overall length of system is 896 mm; the overall length of optical system is 356 mm; the effective F number is 5; the focal length is 40 mm; and the transfer function is greater than 0.65. The field of view of the coronagraph in this paper is larger than the existing coronagraph internationally. However the increase of the field greatly increases the demand of stray light suppression. Therefore, this paper further studies the stray light suppression of the coronagraph. Firstly, the diffraction intensity of the occulter and the external diaphragm is calculated. Secondly, the theoretical models of the diffracted stray light and the scattered stray light of the coronagraph are constructed in this paper. Diffracted stray light is modeled by the theory of fractional Fourier transform and Fresnel-Kirchhoff diffraction integral theory. While the scattered stray light is modeled by ABC model. Scattered stray light is mainly caused by the surface roughness and dust contamination. Thirdly, the stray light of the coronagraph is classed to three levels and is suppressed respectively. The first level of the stray light is the sun light. The second level is the diffracted light from the occulter and external diaphragm. The third level is the diffracted light from the objective frame, the light scattered by the surface roughness and dust contamination, the light scattered by the heat reject mirror and the stray light caused by multiple reflection of the objective surface. Finally the overall stray light level of the coronagraph is tested and the stray light can reach 10-11B⊙ (B⊙ is the brightness of the sun).
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/41469
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	孙明哲. 大视场日冕仪关键技术研究[D]. 中国科学院大学,2014.

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