Development of Microactuator Technologies for Space Applications

Dr. Eui-Hyeok Yang
(Jet Propulsion Laboratory-NASA)
ABSTRACT:
We are developing MEMS-based wavefront correctors using microactuator technologies for adaptive optics applications in future space missions. Active wavefront control is required subsequent to reflection from the primary mirror, particularly to overcome the potentially large spatial frequency errors anticipated with Gossamer type structures. Development of new, low-mass technologies is essential for wavefront correction for next generation optical instruments in Space.

Extremely small inchworm actuators may be required to provide the fine shape correction of primary apertures for future space telescopes. Since conventional inchworm actuator technologies are bulky, there is considerable incentive to develop miniaturized inchworm motors (or actuators). We are developing a linear microactuator technology with large linear motion.

We have demonstrated a large aperture continuous membrane deformable mirror (DM) with a large-stroke piezoelectric unimorph actuator array. The DM consists of a continuous, large aperture, silicon membrane ?transferred? in its entirety onto a 20 ? 20 piezoelectric unimorph actuator array. A PZT unimorph actuator, 2.5 mm in diameter with optimized PZT/Si thickness and design showed a deflection of 5.7 ?m at 20 V. An assembled DM showed an operating frequency bandwidth of 30 kHz and influence function of approximately 30 %.

We have demonstrated a controlled deformation of silicon membrane mirrors using electroactive polymer, providing surface figure correction capability after deployment of primary mirrors. We have designed, modeled and fabricated the G-elastomer-based mirror membranes. We have optically characterized several G-elastomer-based mirror membranes. This concept can be scaled to deployable ultra-large mirror with self-reconfiguration capability.

BIO: Dr. Eui-Hyeok Yang is currently the task manager for several MEMS technology development projects. Dr. Yang is currently leading the development of MEMS-based wavefront correction devices for future large aperture telescopes, and the development of multi-functionalized nanowire sensor arrays for astrobiology applications. He was involved with the technical evaluation of MEMS mirror array technologies being developed for the Multi Object Spectrometer (MOS) project for James Webb Space Telescope (JWST).

Dr. Yang received his B.S, M.S, and Ph.D degree in the Department of Control and Instrumentation Engineering from Ajou University, Korea in 1990, 1992, and 1996, respectively. He joined the Fujita MEMS research group at Institute of Industrial Science, The University of Tokyo, Japan as a visiting postdoctoral researcher in 1996. He received a research fellowship from the Japan Society for the Promotion of Science, Japan from 1996 to 1998. Since 1999, he has been employed at NASA's Jet Propulsion Laboratory (JPL), where he initiated the development of MEMS adaptive optical devices. He has recently been granted several competitive proposals. He was a technical monitor for NASA SBIR projects for the development of active optical mirror devices. He is a Member of IEEE. He is a member of the Technical Program Committee for IEEE Sensors Conference. He is also a member of the Program Committee for the SPIE MOEMS-MEMS Conference. He is a Co-Organizer of Micro/Nanodevices topic of the ASME International Mechanical Engineering Congress and Exposition 2005. He is a recipient of the Lew Allen Award for Excellence for 2003 at JPL.