Enhanced Reliability MEMS Deformable Mirrors for Space Imaging Applications

The goal of this project is to develop and demonstrate a reliable, fault-tolerant wavefront control system that will fill a critical technology gap in NASA's vision for future coronagraphic observatories. The project outcomes include innovative advances in component design and fabrication and substantial progress in development of high-resolution deformable mirrors (DM) suitable for space-based operation. Space-based telescopes have become indispensible in advancing the frontiers of astrophysics. Over the past decade NASA has pioneered coronagraphic instrument concepts and test beds to provide a foundation for exploring feasibility of new approaches to high-contrast imaging and spectroscopy. From this work, NASA has identified a current technology need for compact, ultra-precise, multi-thousand actuator DM devices. Boston Micromachines Corporation has developed microelectromechanical systems (MEMS) DMs that represent the state-of-the-art for scalable, small-stroke high-precision wavefront control. The emerging class of high-resolution DMs pioneered by the project team has already been shown to be compact, low-power, precise, and repeatable. This project will develop a system that eliminates the leading cause of single actuator failures in electrostatically-actuated wavefront correctors – snap-through instability and subsequent electrode shorting and/or adhesion. To achieve this we will implement two innovative, complementary modifications to the manufacturing process that were proven successful in Phase I. We will develop a drive electronics approach that inherently limits actuator electrical current density generated when actuator snap-down occurs, and we will modify the actuator design to mitigate adhesion between contacting surfaces of the actuator flexure and fixed base electrode in the event of snap-down. This project will results in a MEMS DM with 2048 actuators and enhanced reliability driven by current-limiting drive electronics.