以环形线负载驱动模型为基础, 分析了环形线负载驱动变曲率反射镜难以兼顾大中心形变与高精度面形保持的原因; 从薄板弹性理论出发, 得到了一种气动驱动变厚变曲率反射镜物理模型.理论分析表明, 将反射镜的厚度分布从等厚改为变厚, 并采用气压均匀驱动替代推力环环形驱动, 反射镜不仅能产生大的中心形变, 而且在形变过程中的面形精度也远高于环形线负载驱动变曲率反射镜的.基于超硬铝反射镜样片的试验验证了对变厚变曲率反射镜的理论分析; 试验中, 反射镜初始面形精度接近λ/50(632.8 nm), 施加0.032 MPa驱动气压产生约22 μm中心形变时, 反射镜面形精度依然优于λ/20(632.8 nm), 证明该气动驱动结合变厚设计这一技术具有较大的应用潜力.

Based on the model of annular force based actuation, the reasons why it is hard for annular force based variable curvature mirror to obtain a large saggitus variation and maintain a high-accuracy surface figure simultaneously were analyzed. From the elasticity theory of thin plate, a physical model of variable curvature mirror in which pressurization actuation and variable thickness design are combined together was proposed. The theoretical analysis results show that, by making the mirror thickness be variable from the center to the periphery portion and adopting the pressurization actuation, the large saggitus variation can be obtained while the surface figure accuracy can be maintained and higher than the annular line load variable curvature mirror. A duralumin prototype mirror was designed, fabricated and tested. The surface figure accuracy of the mirror before curvature variation is superior to λ/50 (632.8 nm). When a pressure of about 0.032 MPa is imposed, the mirror can provide a saggitus variation exceeding 22 μm and at the same the corresponding surface figure accuracy is still superior to λ/20 (632.8 nm), which verifies the theoretical analysis about variable thickness mirror and proves that the design combination integrating pressurization actuation and variable mirror thickness is a promising technical way to construct an applicable variable curvature mirror.