反射式莱曼阿尔法日冕仪杂光分析

作为色球层光谱的主要成分,莱曼阿尔法辐射在太阳物理学和日冕物理学中具有非常重要的地位。通过观测莱曼阿尔法光谱,可以分析出太阳色球层的主要结构和动态。采用内部遮挡结构,从光学要求出发设计了口径40mm、焦距590mm的反射式日冕仪,用以观测太阳在1.1R⊙～2.5R⊙(R⊙为太阳半径)范围内莱曼阿尔法波段日冕的辐射。该结构应用两片非球面反射镜和一片球面反射镜成像,一片平面反射镜对光路进行偏折。该系统的光学传递函数接近衍射极限,杂散光水平为太阳光球辐射的10-6倍,满足莱曼阿尔法波段日冕的测量要求。

Stray Light Analysis of Reflective Lyman-Alpha Coronagraph

The Lyman-alpha line at 121.6 nm emitted by hydrogen, the most abundant element of the sun, plays a fundamental role in solar and coronal physics. As an intense chromospheres line, it is used to analyze many chromospheres features. To observe the Lyman alpha radiations in the field of 1.1R⊙ to 2.5R⊙ (R⊙ is solar radius), a reflective Lyman-alpha coronagraph with an aperture 40 mm, focal length 590 mm is designed. Two aspheric surfaces and one spherical mirror are adopted, and one piece of reflective mirror is used to fold the light path. The system′s transfer function is close to the diffraction limit, and the main stray light could be suppressed under 10-6 of solar photosphere radiation, which is in an acceptable level of the Lyman-alpha corona measurement.