Deformation Analysis of Electro-statically Driven Micro Porous Deformable Mirror

Micro deformable porous mirrors are designed and investigated in this work. Finite element methods are used to analyze mirror deflection induced by electrostatic force. The porous micro mirror is designed by bulk micromachining and bonds with aluminum plate which is ground electrode with photo resist for its good adhesion ability. This design has advantages of avoiding warpage, using less masks, and easily fabricated. It is found mirror boundary types and holes shapes and arrangement in mirror would affect deflection under applying voltage. Spring like boundary will induce larger deflection than traditional clamped boundary condition. However, the effect is more obvious for mirror with round holes in radical direction. Although porous mirror has smaller electrode area and electrostatic force than mirror without holes, yet it has larger displacement. The effect of holes overcomes disadvantage of smaller driving force due to avoiding air resisting force as mirror having airtight bounding. In this study, spring-like boundary has advantages of better performance and easier alignment in mirror fabrication. Therefore, it is useful for mirror design and fabrication in practice.