基于日冕仪应用的超光滑、低散射、三谱段反射镜的研制

日冕是耀斑和日冕物质抛射等太阳活动的主要来源地。人们用日冕仪对它的观测研究，有利于揭示日冕起源的奥秘。目前还没有用一个光学系统实现三谱段观测的内掩式日冕仪。杂光抑制是日冕仪研制的重要指标，而主镜的散射是其杂光重要的来源。中高频粗糙度是引起反射镜散射的主要因素。超光滑基底和薄膜粗糙度相互影响的机制尚有争论。前期研究发现二维材料能够显著降低基底粗糙度，由此推测可以用它来研究这一问题。.本课题拟采用二维材料作为基础模型来研究超光滑基底和薄膜中高频粗糙度相互影响的机制，采用亚1/4波长和布拉格衍射方法设计三谱段多层膜并制备反射镜。研制出超光滑、低散射、三谱段反射镜，它在极紫外和121.6nm处的反射率大于20%，在可见光波段的反射率大于40%，高频粗糙度小于0.20nm。阐明超光滑基底和薄膜粗糙度相互影响的机制。.本课题的成功研制，将为我国开展三谱段、高分辨率、高灵敏度日冕仪的研制奠定坚实的基础。

Solar corona is the main source of solar activities, such as solar flares and corona mass ejections. The study on imaging detection of corona by the coronagraph will contribute to unveiling the mystery of the origin of corona. Until now, there is no such an internally-occulted coronagraph that uses an optical system to realize three-waveband detection. Suppression of stray-light level is the key index of coronagraph research, and light scattering from the main reflective mirror is the important source of its stray light. Surface roughness at medium and high spatial frequencies is main factor that results in scattering of the mirror. There is still a debate about the mechanisms of roughness interplay between supersmooth substrate and thin films. It is found in previous study that two dimensional material can significantly reduce roughness of the supersmooth substrate, and we infer that we can use it to study this problem.. This project aims to study the mechanisms of roughness interplay between supersmooth substrate and thin films by two dimensional material as a basic model, and design the three-waveband multilayer mirrors by sub-quarter-wave and Bragg diffraction methods and fabricate them. We will achieve three-waveband reflective mirrors, they have a reflectance of larger than 20% at extreme ultraviolet band and 121.6 nm, 40% at visible band, and they have a surface roughness of less than 0.20 nm at high spatial frequency. We will elucidate mechanisms of roughness interplay between supersmooth substrate and thin films. . This study will lay a solid foundation for research of three-waveband coronagraph with high resolution and sensitivity for our country.