Static structure and wavefront error analysis of the primary mirror of an experimental telescope

Abstract

This paper presents the analysis of static structure and wavefront error (WFE) of a telescope experimental model’s primary mirror. The experimental telescope with 280mm diameter primary mirror had been assembled and aligned in 2011. The WFE result was not perfect. In order to find out the root cause of the WFE, the static structure analysis had been applied to the structure model of the telescope assembly. Some assumed effects which may cause deformation of the primary mirror had been proposed, such as gravity effect, iso-static mount (ISM) bonding effect, thermal expansion effect, etc. According to each assumed effect, we established a corresponding model and boundary setup. The numerical model was also analyzed by static structure analysis software and opto-mechanical analysis software to obtain numerical WFE and Zernike polynomials. The numerically synthetic optical system WFE was compared with measured system WFE of the telescope. According to the results of these deformation effects of the primary mirror, we could get the root cause of the system WFE. In the next generation of telescope, the opto-mechanical design and alignment process would be refined, and applied to the new optical system.