Optimized Design Of The Supporting Structure Of The Secondary Mirror Of The Space Remote Sensing Camera

With the rapid development of space remote sensing information technology,it plays an important role in people’s livelihood,national defense and other aspects.In the new era,the application of remote sensing puts forward strict requirements for optical system,so it is urgent to develop high-resolution,lightweight space camera.This kind of space camera has more stringent requirements for the position accuracy and rigid displacement design of optical elements.As a supporting structure to install optical elements and ensure the position accuracy of optical elements,it is one of the technical problems in the current research.In this thesis,a secondary mirror supporting structure with high thermal stability and low shielding ratio is designed for a pre-developed model.(the diameter of main mirror is more than 1500 mm,the diameter of secondary mirror is not less than 340 mm,the distance between primary and secondary mirrors is close to 1700 mm,and the mass of supporting structure is less than 165kg).Firstly,this thesis introduces the common materials used in the secondary mirror support structure of space camera,compares their specific stiffness,steady-state thermal deformation,transient thermal deformation and mechanical thermal properties,and selects SiC/Al,titanium alloy TC4,invar,SiC as the design and preparation materials of the support structure.On the basis of inheriting the successful experience,considering the requirements of model design and the characteristics of optical system,taking the fundamental frequency and weight as constraints,two supporting configurations of thin-walled tube type and truss mesh type are selected and designed.Through comparison,the truss mesh type is determined as the design scheme.By adopting multi-objective size and Rayleigh method,the secondary mirror,secondary mirror bracket and truss type front mirror tube assembly are optimized to build the optimal secondary mirror support configuration.After that,the static and dynamic simulation analysis of the whole assembly(including secondary mirror,secondary mirror bracket and front mirror barrel)and the rubber spot overload analysis are carried out.The results show that the design constraints such as secondary mirror shape,basic frequency of the whole machine,rigid displacement and strength are all satisfied,and the correctness of the optimization scheme is verified.