膜基反射镜的面形控制是研制膜基反射镜的关键技术之一。设计了一种基于模糊逻辑控制技术的膜基反射镜面形控制系统,包括面形设计、面形控制、面形分析和面形控制仿真等功能模块。采用Visual C#和MATLAB混合编程来实现系统功能,并在仿真系统中嵌入了ANSYS有限元分析功能。采用控制反射镜中心截面矢高的方法设计控制器,利用Zernike多项式拟合得到膜基反射镜的面形及其像差。对口径为300 mm、F/5的膜基反射镜进行了面形控制和扰动响应仿真分析,最终得到面形误差RMS值为71λ(λ=632.8 nm),在相同条件下,该结果与根据薄膜大扰度形变理论得到的面形误差结果相一致。
Surface shape control is one of the key technologies for the manufacture of membrane mirror.A new surface shape control system for membrane mirror was designed on the basis of fuzzy logic control technology which contained such function modules as surface shape design,control,analysis,simulation and etc.The system functions were realized by using hybrid programming of Visual C# and MATLAB.And the ANSYS finite element analysis function was embedded in the simulation system.The controller was designed by means of controlling the sag of the mirror′s central cross-section.The surface shape of the membrane mirror and its optical aberration were obtained by using Zernike polynomial fitting.The simulation analysis of surface shape control and disturbance response was performed for a membrane mirror with 300 mm aperture and F/5.The result of the simulation shows that by using the designed control system,the RMS wavefront error of the mirror can be decreased to 71λ(λ=632.8 nm),which is consistent to the surface error of the membrane mirror obtained by the large deformation theory of membrane under the same condition.