Enhanced Fabrication Processes Development for High Actuator Count Deformable Mirrors

We propose to design and fabricate a MEMS micromirror array consisting of 1021 ultra-flat, close-packed hexagonal mirror elements, each capable of 6mrad of tip and tilt, and 1.7um of piston (TTP) motion with sub-nanometer precision as required for a space-based telescope using a hyper-contrast coronagraph for terrestrial planet finding. Fabrication process enhancements developed in the Phase I effort to increase device yield by significantly reducing the defect density in polysilicon films and reduce wafer bow by modifying thin film deposition processes, will be integrated in to the DM fabrication process to produce a device with 100% actuator yield and an unpowered peak-to-valley surface figure error of<500nm - well within the dynamic range of the DM actuators. This large array of mirror segments with tip-tilt-piston degrees of freedom and?/100 optical quality would constitute a significant technological advance and would become an enabling component for the high contrast visible nulling coronagraph instruments planned for exoplanet imaging missions.