A micromachined deformable mirror for optical wavefront compensation

A silicon micromachined deformable mirror (mu DM) has been developed by Boston University and Boston Micromachines Corporation (BMC). The mu DM employs a flexible silicon mirror supported by mechanical attachments to an array of electrostatic parallel plate actuators. The integrated system of mirror and actuators was fabricated by surface micromachining using polycrystalline silicon thin films. The mirror itself measures 3 mm x 3 mm x 3 mum, supported by a square array of 140 electrostatic parallel-electrode actuators through 140 attachment posts. Recently, this mu DM was characterized for its electromechanical and optical behavior and then integrated into two laboratory-scale adaptive optics systems as a wavefront correction device. Figures of merit for the system include stroke of 2 mum, resolution of 10 nm, and frequency bandwidth of 6.7 kHz. The device is compact, exhibits no hysteresis, and has good optical quality.