薄主镜支撑系统分为轴向和侧向支撑两部分，侧向支撑承担主镜垂直于光轴方向的重力分量。介绍了pushpull-shear侧支撑及能动校正原理，并针对一块8 m 口径薄主镜进行了侧支撑设计。设计了5种备选侧支撑方案，并考虑到主镜对面形的能动校正能力，借助有限元计算对它们进行了分析和比较，选出了一种最佳方案作为8 m 薄主镜的侧支撑方案。该侧支撑方案共有64 个侧支撑点，每个侧支撑点仅施加沿主镜切向的支撑力。当主镜竖直放置时，主镜能动校正后的镜面均方根值为19.2 nm，校正力范围为-318.9~301.4 N。相比传统push-pull-shear侧支撑方式，该侧支撑方案结构简单，易于实现，同时支撑效果良好。

The support system of an thin primary mirror consists of axial supports and lateral supports. Lateral supports mainly support the component force of the mirror’s gravity normal to the optical axis of the mirror. The push- pull- shear lateral support and the principle of active correction are introduced, and 5 alternative lateral supports are designed for an 8 m active thin mirror. Taking account of the active correction of the primary mirror and comparing the 5 alternatives via the finite element method, the best lateral support of the 8 m mirror is determined. The best lateral support consists of 64 lateral support points, and each point only applies an tangential force. The root mean square of the surface of the 8 m mirror after active correction is 19.2 nm when the mirror is mounted vertically and the range of the correction forces is - 318.9~301.4 N. Compared with regular push- pull- shear lateral support, this lateral support is simpler in structure, easier to implement and has good supporting performance.