Picometer-Resolution MEMS Segmented DM

Microelectromechanical systems (MEMS) technology has the potential to create deformable mirrors (DM) with 10^4 actuators that have size, weight, and power specifications that are far lower than conventional piezoelectric and electrostrictive DMs. However, building a MEMS DM with a relatively large aperture that is flat in the unpowered state is challenging. Currently, a large portion of the mirror stroke must be used to flatten the MEMS DMs. In the case of the large-stroke segmented MEMS DMs manufactured by Iris AO, there is sufficient stroke for wavefront correction after flattening. However, the resolution is significantly reduced because the dynamic range of the digital-to-analog converters (DAC) used to operate the DM is spread over multiple microns of stroke rather than the 0.5 micron range required for a coronagraph. This Phase I SBIR will make substantial improvements in the fabrication process of MEMS segmented DMs that reduce the deleterious residual surface-figure errors. It will do so by systematically addressing the sources of the segment position variations as well as addressing low-spatial frequency chip bow that can result in large peak-to-valley deformations across the DM array. The Iris AO DM architecture will also be modified to enable picometer resolution actuation with ultra-precision drive electronics.