Research On The Floating Support Of 1.2m Ground-based Primary Mirror

In order to meet the needs of astronomical observations and the military application, we put forward higher requirements for collecting ability and the resolution power of the ground-based telescopes. Primary mirror support design for large aperture telescope is one of the key technologies of telescope design, which determines the image quality of the telescope. Based on the research contents on 1.2m primary mirror floating support of ground-based telescope, in order to meet the structure stiffness and stability requirements,the finite element method is applied to analyze the static and dynamic performances of the primary mirror support system so that the structure of mirror cell components is optimized.Describing the role of ground-based telescopes which commonly adopt the structure of the optical system, the development situation of large aperture telescope at home and abroad is introduced. The different kinds of support on telescope primary mirror are elaborated.We introduce the evaluation standard and methods of the mirror surface error and compare the advantages and disadvantages of various axial and radial for the large aperture mirrors. Then the overall floating support design program is determined,including the axial mechanical whiffletree support structure, radial equilibrium lever weight support and other auxiliary protection support.Under the guidance of the overall support design program, the support of 1.2m primary mirror is designed and the mirror cell assembly is established. As the parameters of the primary mirror determined, the structure of axial and radial support is designed respectively. The axial support design includes the number of support points, support position optimization, mechanical Whiffletree design and axial protection support design. The radial support design includes support position optimization and radial equilibrium lever weight support design. The topology of initial mirror cell can lightweight the mirror cell and improve the first order natural frequency of the primary mirror cell.In the primary mirror cell system based on the simplified model, bearing contact and ball hinge contact is established. Then establish the finite element model of the primary mirror cell assembly and nonlinear static analysis was taken. Thus we evaluate surface performance of the primary under different work situation to know if it meets the design requirements.Finally dynamics analysis of the primary mirror cell system is conducted, including modal analysis, random vibration analysis and the multi-body dynamics analysis. The dynamic performance of the primary mirror cell system is evaluated.