Electrostatic-pneumatic MEMS deformable mirror for focus control

A novel actuation scheme for MEMS deformable mirrors is presented in this paper. In this method electrostatic actuation is combined with pneumatic actuation to achieve either concave or convex surface curvature and to increase the optical focus range of the mirrors. The fabricated device consists of two membranes made of the photoset epoxy SU-8. One membrane serves as the deformable mirror and the other one as the pneumatic actuator. The principle of the operation, fabrication process and deflection curves are presented.