中文摘要：

提出了一种加工离轴非球面的预应力环抛方法，基于预应力加工方法的基本原理，利用环抛机来磨制离轴非球面．设计了一套专门的加载装置，将拼接镜面中具有不同离轴量的非球面子镜转化成曲率半径相同的球面子镜进行磨制，可以在同一台环抛机上进行抛光．利用这种方法，花费连续40h的时间，磨制了一块按照中国30m极大口径望远镜（CFGT）主镜参数比例缩小的离轴抛物面，顶点曲率半径21．6m，离轴量3．6m，离轴口径为330mm，最大非球面度为16μm．试验表明该方法效率高，适用于批量加工，特别是极大口径天文望远镜拼接主镜的大批量非球面子镜研制．

英文摘要：

In this paper, a special technique is proposed to polish the off-axis aspherical mirror for a large segmented mirror. It is based on a process of stressed mirror polishing with the continoues polishing machine. During the polishing procedure, a stressing fixture attached to the mirror segment was designed to transform the surface shape of aspheric mirror to a destined sphere. So segments can be polished into same sphere on an contineous polishing machine （CPM）. It took about 40 hours to continuously polish a scaled-down sub- mirror of CFGT using the technique. The mirror is 330 mm in diameter, 3.6 m in off-axis distance and 21.6 m in radius of curverture. The maximum asphericity is about 16 microns. High polishing efficiency was shown and it might met the needs of manufacturing of a large segmented telescope mirror.