Eui-Hyeok.Yang
Jet Propulsion Laboratory/California Institute of Technology
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 mm 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.