Flexure mount for a MEMS deformable mirror for the Gemini Planet Imager

Abstract

Small deformable mirrors (DMs) produced using microelectromechanical systems (MEMS) techniques have been used in thermally stable, bench-top laboratory environments. With advances in MEMS DM technology, a variety of field applications are becoming more common, such as the Gemini Planet Imager’s (GPI) adaptive optics system. Instruments at the Gemini Observatory operate in conditions where fluctuating ambient temperature, varying gravity orientations and humidity and dust can have a significant effect on DM performance. As such, it is crucial that the mechanical design of the MEMS DM mount be tailored to the environment. GPI’s approach has been to mount a 4096 actuator MEMS DM, developed by Boston Micromachines Corporation, using high performance optical mounting techniques rather than a typical laboratory set-up. Flexures are incorporated into the DM mount to reduce deformations on the optical surface due to thermal fluctuations. These flexures have also been sized to maintain alignment under varying gravity vector orientations. This paper is a follow-up to a previous paper which presented the preliminary design. The completed design of the opto-mechanical mounting scheme is discussed and results from finite element analysis are presented, including predicting the stability of the mirror surface in varying gravity vectors and thermal conditions.