Microelectromechanical deformable mirrors

A new class of silicon-based deformable mirrors is described. These devices are capable of correcting time-varying aberrations in imaging or beam form ing applications. Each mirror is composed of a flexible silicon membrane su pported by an underlying array of electrostatic parallel plate actuators. A ll structural and electronic elements were fabricated through conventional surface micromachining using polycrystalline silicon thin films. A layout a nd fabrication design strategy for reducing nonplanar topography in multila yer micromachining was developed and used to achieve nearly flat membrane s urfaces. Several deformable mirrors were characterized for their electromec hanical performance, Real-time correction of optical aberrations was demons trated using a single mirror segment connected to a closed-loop feedback co ntrol system, Undesirable mirror contours caused by residual stress gradien ts in the membrane were observed.