The Design and Fabrication of Capillary Force Microactuators for Deformable Mirrors

Adaptive optics (AO) is a revolutionary technology that enhances the quality of astronomical images by correcting aberrations in them caused by atmospheric turbulence and distortions in the primary mirrors of large telescopes. The technology relies on manipulating arrays of microactuator devices mounted behind a deformable secondary mirror to correct errors in wave-fronts of incoming light. Current microactuators used in deformable mirrors lack sufficient force and stroke needed for higher resolution space imaging. This paper focuses on the fabrication of a novel type of microactuator called a capillary force actuator that is theoretically capable of producing 10 to 100 times more force than current actuators of similar size. Prototype devices currently being fabricated at the University of Virginia are too large for adaptive optics applications due to the subtractive fabrication process used. This paper discusses the design and implementation of a new fabrication process that uses nickel electroplating to manufacture capillary force actuators. The unique fabrication techniques developed allow the actuators to be scaled down, while maintaining necessary force and stroke needed for adaptive optics.