Design and fabrication of a large-stroke MEMS deformable mirror for wavefront control

Adaptive optics is a technology that improves the performance of optical systems by reducing wavefront distortion. Currently, it is playing a more important role in astronomy, laser physics, nonlinear optics, medicine, vision and the defense industry. In this paper, we demonstrate a microelectromechanical system (MEMS) deformable mirror that is made of a 2.15 mu m thick polyimide film and is actuated by electrostatic force. We made a large-stroke MEMS deformable mirror with a 20 mm diameter circular opening and 67 hexagonal actuation electrodes. We also used modeling software, ANSYS, to simulate the deformation behavior of the membrane and discussed the device parameter tuning for versatile applications. The maximum stroke was 39 mu m as 195 V was applied. Because of the large stroke of the device, the resonant frequency was approximately 40 Hz. The resonant frequency can be increased by thickening the polyimide membrane. The polymer deformable mirror is a strong candidate for active wavefront control, based on our experimental results.