介绍了主反射镜的一种轻量化结构设计；
A kind of structure design of lightweight of primary mirror is introduced in this paper.
就是从透镜(或者主反射镜)到焦点的距离，通常单位是毫米(mm)。
This is the distance (usually in mm.) from the lens (or primary mirror) to the point where the telescope is in focus (focal point).
刚开始时主反射镜的瑕疵造成影像模糊；1993年另一次太空任务修正此瑕疵及其它问题。
A defect in the primary mirror initially caused it to produce fuzzy images; in 1993 another shuttle mission corrected this and other problems.
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