Design of large aperture primary mirror and the support based on FEM

In order to meet the requirements of high stiffness, strength and thermal dimensional stability for large aperture mirror, material selection, lightweight pattern and the design of support were taken into account in the design of Ф1130mm primary mirror of a Cassegrain space telescope. A new design with flat and opened back, triangular combined with honeycombed hole light-weighting structure is proposed. Three major points support and multiple points assistant support structure could keep both high rigidity of structure and fine thermal dimensional stability of the primary mirror. By adopting computer aided engineering (CAE) technique, the static and dynamic stiffness as well as thermal character of the primary mirror component were analyzed. Analysis results indicate that the surface accuracy reach to λ / 8 PV, λ / 30 RMS (λ = 632.8nm) under gravity and 4°C uniform temperature change, the first order frequency of the primary mirror component is 210 Hz, which can meet the requirements of space application.