在超大口径光学制造中,镜体背部空间狭小,转台承载能力有限,要求光学制造的支撑结构尽量简单；镜体承受加工载荷且弥漫加工磨料,要求支撑系统对加工载荷和环境不敏感；此外,为便于在线检测,缩短检测周期,还要求支撑系统具有较高的调整精度和稳定性.设计了一种均力型静压支撑系统,先测试了单个支撑的均力性及刚度,预测了压印效应的大小；随后阐述了支撑系统的控制方法；最后实现了系统集成及其图形用户界面(GUI)界面操作.将该系统用于2m SiC 反射镜的光学加工,可将压印效应均方根(RMS)值控制到13.1 nm≈λ/48,满足加工需要；用于立式检测,系统对镜体倾斜和俯仰角可监测到的角度范围为0.34″~0.48°,以及沿Z 方向±5 mm 的运动；对应曲率中心在XY 平面的调节范围dR 最大值50 mm,最小值为10 μm,与电荷耦合器件(CCD)像元尺寸接近,满足立式检测需要.对目前具有重大需求的2~4 m 量级反射镜而言,该系统具有较好的适用性.

In the process of manufacturing ultra-large mirrors,there is very limited space beneath the mirror′s back,the machine platform has limited carrying capacity,so the polishing support system (PSS) should be structured simply.Also as the mirror is suffering from fabricating load and polishing powder which is very“dirty”spreads everywhere,PPS should not be sensitive to polishing load and its working environment.Moreover,when one wants to speed up the polishing through online testing,PPS should be adjustable and stable enough.An equalforce hydrostatic support system is designed,afterward the equal-force performance and static stiffness of PSS′s single support structure are tested,then the print-through effect is predicted,finally the corresponding control method is proposed and PPS is integrated with (GUI) operation.Applied to the polishing of a 2 m SiC mirror,PPS restricts the magnitude of print-through effect to 13.1 nm≈l/48,which is considered stiff enough.And PPS achieves an angle adjusting region of 0.34″~0.48° and a ±5 mm motion along Z axis for the mirror.The angle adjustment makes the corresponding XY-plane motion of the curvature center range from 50 mm to 10 mm,which is close to the size of charge couple device (CCD)′s basic unit,showing it suitable for mirror adjustment during vertical testing.The proposed hydrostatic support system has a good adaptability to 2~4 m class mirrors,which are in great demand.