Design and qualification of an aluminum deformable mirror for spaceborne electro-optical payloads

Abstract

The goal of deformable mirrors (DMs) is to correct aberrated optical wavefronts in spaceborne electro-optical (EO) payloads. It is used as part of an active/adaptive optics system. A continuous-surface, metal-based DM is highly reliable and less complex to assemble, has better stability of the active surface, is less expensive, and can be manufactured quickly. In addition, metal DM with actuation away from the active surface makes the overall configuration scalable. Continuing our previous work on deformable metal mirrors, this work presents the design, validation, and qualification of an aluminum DM using 25 piezoelectric actuators, which include an actuator in the center of the mirror, to improve the spherical aberration correction accuracy. The optomechanical design and analysis of the deformable mirror assembly (DMA) are also presented for performance and survival loads. Later, a qualification model (QM) was built with vacuum-compatible closed-loop piezoelectric actuators. The correction accuracy was demonstrated at the QM by correcting aberrations in the mirror itself. The QM was successfully tested in the space environment in the ThermoVac for operating temperature limits of 20°C±5°C and demonstrated survivability for storage temperature limits of 20°C±40°C. Likewise, the survivability of QM for launch environments such as sinusoidal and random vibration loads is demonstrated. The successful completion of all these tests has improved the maturity of this technology to the technology readiness level of 7 and is now ready to be configured for the appropriate spaceborne EO payload.