According to technical requirements of 1.3 m primary mirror’s supporting

a type of mounting system was designed and analyzed. A technical plan of center bearing with 18-point axial and mercury tube lateral support system was determined. For the light-weight primary mirror with complex structure

the 18-point support positions of axial mounting system were decided by equilibrium principle

structure analysis and interpolation. After the 18-point axial support system was described in detail

the structural deformation and design error were also analyzed. Three design variables on mercury tube lateral support system were selected according to force analysis of the primary mirror at vertical direction. Mercury tube lateral support system was designed according to the requirement of minimum deformation results at

Z

direction and 12 load cases finite element analysis results. Finally

in order to reduce the effect of temperature variation on the center bearing design

the invar steel was chosen. Meanwhile

a transitional fit shaft housing was designed to reduce the influences on the direct contact between support sphere and primary mirror in detailed design. The experiment results have been obtained with mirror surface PV error of 0.7 λ and RMS error of 0.15 λ using Zygo interferometer. The experimental results indicate that the mounting structure can satisfy the system requirement with excellent stabilization and reliability. Based on the analysis results

thickness of the primary mirror can be reduced more for designing light-weight mirror.