The Cassegrain telescope system was design for space environment. The correct lens mount assembly is included as
correct lens, lens mount, spacer, mount barrel and retainer. The system mass budget allocated to correct lens assembly
was 5 Kg. Meanwhile, according to optical design the correct lens is made from fused silica, the lens diameter is 130
mm, and the mass is 2.3 Kg. Therefore, remain mass budget is 2.7 Kg; including the lens mount, spacer, mount barrel
and retainer. The telescope system deformation is mainly caused by thermal deformation on space orbit. The correct lens
mount was made from invar material in initial design. The CTE (Coefficient of Thermal Expansion) of invar is only 1*
10-6/°C, low CTE would be resistant to thermal deformation, but invar density is 8* 10-6 kg/mm3. If all components were
made from invar, the total mass was over 2.7 kg. Thus, the components material would consider titanium alloy (CTE is
8.6* 10-6/°C, density is 4.43* 10-6 kg/mm3) or aluminum alloy (CTE is 23.6* 10-6/°C, density is 2.81* 10-6 kg/mm3).
The titanium alloy density is 1.83 times lighter than invar, but CTE is 8.6 times higher. The aluminum alloy density is
2.84 times lighter then invar, but CTE is 23.6 times higher. The lens mount thermal deformation would effect correct
lens surface wavefront error and introduce optical aberration. This article analyzes the correct lens assembly thermal
deformation and optical performance in different lens mount material. From above conditions, using FEM (Finite
Element Method) and optical software, simulation and optimization on the lens mount design have been performed to
achieve system mass requirement.