FEM analysis and experiment study of Ultra Thin Active Mirror

摘要

Ultra-thin mirror has a large diameter-thickness rate, so it will be more deformable because of the change of working conditions. We have performed an ultra thin mirror with 1.5mm glass membrane of 340mm diameter which is attached to a sample support structure through a set of precise screws. In this paper, some analyse and computing simulation for active ultra thin mirror surface by using finite element method (FEM) are introduced:(1) simulated an ultra thin mirror with a large ratio by software "patran";(2) With Zernike polynomials several low-order aberrations are got, which simulate the profile error after ultra thin mirror fabrication and the deformation because of change of working conditions; (3) After getting the influence function of single actuator, the optimum scheme of actuator array for an ultra thin active mirror with maximum corrective capability is achieved;(4)The optimal size of flange which attaches the actuator to glass membrane is determined;(5) The test for correcting the surface Figure of this sample mirror demonstrates the correctness of result of FEM.