Fabrication and Simulation of Large-Scale MEMS Deformable Mirror for Wave Front Active Control

Adaptive optics (AO) is a technology which improves the performance of optical systems by reducing the effects of rapidly changing optical distortion. Nowadays, it makes more important role in astronomy, laser physics, nonlinear optics, medicine, vision and defense industry. We demonstrate that wave front active control by combining wave front sensor and MEMS deformable mirrors which made of polyimide thin film actuated by electrostatic force is one possible solution. Wave front sensor detects the image and aberration could be described with Zernike polynomials, and the distorted wave-front may be corrected by deformable mirror. In this thesis, we fabricate a large-scale MEMS deformable mirror with a 20mm diameter circular opening and 67 hexagonal actuation electrodes. Moreover, we use commercial software, Ansys, to simulate the deformation behavior of the membrane with different electrodes applied and give some device parameter tuning for versatile application. The maximum stoke is 39um as 195 volts applied to 67 electrodes. Due to the large-scale of our thin membrane, resonant frequency is around 8 Hz. Besides, we also discuss some possible ways to improve device characteristics and we think deformable mirror has a good potential for wave front active control based on our experiment results.