对大口径主镜的侧向支撑结构进行了优化, 以便最大限度地降低重力作用下的镜面变形。首先, 从理论上给出了一种优化主镜边缘侧支撑结构的判据和思路, 然后, 引入边缘切向剪切侧支撑原理, 阐述了这种支撑形式的优化思想和优势。以口径为2060 mm的扇形轻量化主镜作为分析实例, 采用16个边缘离散支撑点, 优化设计等角间距侧向支撑, 并针对轻量化主镜的结构特点和等角间距支撑下支撑力值相差较大的缺点, 将等角间距改为不等角间距侧向支撑, 分析推导了相应的支撑力公式。结果显示, 改进后的支撑形式提高了系统的支撑刚度, 镜面变形由原来的1.723 nm降为1.633 nm。所研究的边缘切向剪切支撑方式很大程度上保证了主镜镜面面形, 对不同口径的扇形孔轻量化主镜的设计有普适性。

The lateral support structure of a large aperture primary mirror was researched and optimized to effectively reduce the deformation of the primary mirror under the gravity. First, an idea and criterion to optimize the edge-lateral support structure was provided theoretically.Then, on the basis of the tangential shearing support principle, the optimization procedure of the support structure and its merit were explained. Based on the principle, a lightweight mirror with a diameter of 2 060 mm was taken as an example, and an equal-angle lateral support was optimized by using 16 discrete points. According to the characteristic of the lightweight mirror, the original supporting structure was improved to be the no-equal-angle lateral support to avoid the disadvantage that the gap between the support forces was large in previous structure. The results indicate that the supporting stiffness of the system has been enhanced and the mirror deformation is reduced from 1.723 nm to 1.633 nm. It concludes that the edge tangential shearing support structure which is fit to the lightweight mirror with sector hole can keep the mirror surface figure to a large extent. So this method provides a new option for the lateral support of large-aperture lightweight mirror.