为了获得超高精度面形的光学元件并验证离子束的修正能力，对应用离子束修正大面形误差光学元件的问题进行了实验研究。通过改变离子源光阑尺寸的方式获得了不同束径的离子束去除函数，并对一直径为101 mm、初始面形峰谷(PV)值为417.554 nm、均方根(RMS)值为104.743 nm的熔石英平面镜进行了离子束修形实验。利用10、5、2 mm光阑离子源的组合，进行了12次迭代修形，最终获得了PV值为10.843 nm、RMS值为0.872 nm的超高精度表面。实验结果表明，应用离子束可以对大面形误差光学元件进行修正，并且利用更大和更小束径离子束去除函数的组合进行优化，可以进一步提升加工效率和精度。

In order to gain ultra-precision optical elements and to verify the machining capability of ion beam figuring (IBF), the figuring of large optical surface error by ion beam is investigated. Different scale removal functions are gained by changing different ion diaphragms. An 101 mm fused silica flat optical element with initial surface figure peak-valles (PV) value of 417.554 nm and root mean square (RMS) value of 104.743 nm is figured by this mean. Through twelve iterations of 10, 5, 2 mm diameter ion diaphragms, an ultra-precision optical surface with PV value of 10.843 nm and RMS value of 0.872 nm is gained. The result shows that the large optical surface error can be figured by IBF, and the efficiency and precision can also be improved by larger and smaller ion diaphragms.