Optimization Design Of Splicing Mechanism For Membrane Diffraction Primary Mirroe

It is an important research area to development high-precision and large-aperture telescopes in the field of space optics.Compared with the reflective optical system,the diffractive optical system made by membrane material has the characteristics such as large aperture and lightweight,the diffractive optical system can reduce the costs of manufacturing and launch significantly.The sub-mirror slicing technology is another way to realize large aperture,and this technology has received widespread attention in recent years.Using this technology large-aperture main mirrors are made by splicing some small-aperture sub-mirrors according to a certain rule,the volume and weight can be reduced effectively by using the splicing method,so it has board application in the future.In this paper,for the membrane diffractive splicing system in the ground experiment environment,some analysis and design have done such as membrane mirror optimization,the completely splicing machine design and the whole device accuracy.The main research contents are divided into the following aspects:Firstly,the deformation of the sub membrane mirror under the action of gravity is calculated based on the large deformation theory of the sheet and by finite element analysis software.The membrane shape accuracy regular pattern is analyzed by finite element analysis software under various working conditions.The membrane shape accuracy has be improved to PV?0.15?m by adopting the pre-stress applied on the membrane edge.Secondly,a splicing mechanism of membrane diffractive mirror is designed,and the mechanism can realize the movement and rotation along with three coordinate axes.The structure,size and stiffness of the main component of the mechanism are calculated and analyzed.The adjustment accuracy of the entire drive shaft can reach 0.3nm,and the axial tensile stiffness is 18.6N/?m,radial bending stiffness 0.0074N/?m;Finally,the coupling and precision analysis of the sub membrane mirror splicing mechanism is performed.By establishing the geometric relationship model between the sub membrane mirror and the adjusting element,the coupling equation is solved and the parameter adjustment matrix is established.The coupling accuracy of splicing and the entire device splicing accuracy are calculated by finite element analysis software,the accuracy analysis results show that the maximum translation error of the main mirror after decoupling splicing is 0.354?m<0.5?m,the maximum rotation error is 1.03?rad<4.85?rad,the shape accuracy of sub membrane mirror PV values reaches 0.1342?m<0.15?m.All of the results meet the technical requirements given in this paper,to complete the optimization design of the entire splicing mechanism.