空间光学技术研究室知识库

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. © 2016, Science Press. All right reserved.