A High Stroke Actuator Micro-mirror Array Designed for Adaptive Optics

Abstract

A micro-mirror with large out-of-plane displacement actuator with three polysilicon layers fabrication process is designed for adaptive optics application. The optimized micro-mirror actuating structure consists of three individual levers, each of which is actuated by electrostatic attractive force with the plane-parallel structure to produce a large upward displacement at the end of the long arm of the lever with the lever principle. Finite element analysis (FEA) models are built to calculate the maximum upward displacement of the long arm. The actuator with 320 um long arm and 80 um short arm were designed by 2um thick Poly1 layer, while the electrodes were designed by Poly0 and mirror plate was designed by Poly2 with a polish process afterwards. The micro-mirrors can be tightly arranged in a hexagonal array to be applied in adaptive optics (AO) system as a deformable mirror. An AO simulation system is built to test the aberration correction effect of the micromirror array. The results showed that the 61 micro-mirror array is better than 37 micro-mirror array in aberration correction, which showed good application prospect of this high stoke micro-mirror array in AO systems.