Abstract 318

Submitted by Thomas BIFANO

Authors

S. Cornelissen

Affiliations

Boston Micro-Machines

Abstract

We report on the development of BostonMicromachines’ micro-electromechanical (MEMS) deformable mirrors designed for ground and space-based astronomical instruments using adaptive optics. Four different deformable mirror designs, a 144 and 1024 element continuous membrane (32x32), a 4096 element continuous membrane (64x64), and a 331 hexagonal segmented tip-tilt-piston are in development for use in a number of astronomical imaging instruments such as the Gemini Planet Imaging Instrument, and the visible nulling coronograph being developed at JPL for NASA’s TPF mission. The design of these polysilicon, surface-micromachined MEMS deformable mirrors builds on technology that was pioneered at Boston University and has been used extensively to correct for ocular aberrations in retinal imaging systems and for compensation of atmospheric turbulence in free-space laser communication. These light-weight, low power deformable mirrors will have an active aperture of up to 25.2mm consisting of thin silicon membrane mirror supported by an array of 1024 to 4096 electrostatic actuators exhibiting no hysteresis and sub-nanometer repeatability. The continuous membrane deformable mirrors, coated with a highly reflective metal film, will be capable of up to 4µm of stroke, have a surface finish of <10nm RMS with a fill factor of 99.8%. The segmented device will have a range of motion of 1um of piston and a 600 arc-seconds of tip/tilt simultaneously and a surface finish of 1nm RMS. The individual mirror elements in this unique device, are designed such that they will maintain their flatness throughout the range of travel. New design features and fabrication processes are combined with a proven device architecture to achieve the desired performance and high reliability. Presented in this paper are device characteristic and performance results of these devices.