CubeSat Deformable Mirror Demonstration

The research undertaken in the CubeSat Deformable Mirror Demonstration addresses the need for in-space characterization of MEMS deformable mirrors for applications such as high contrast imaging and atmospheric sounding from space-based platforms. Active and adaptive optics systems (Figure 1) have several applications in space-based imaging and communications. Deformable mirrors are a key technology needed to perform the optical corrections in wavefront control systems, including high contrast imaging of exoplanets with space telescopes and space-based free space optical laser communications. These wavefront control systems can be used for either image correction from on-orbit disturbances (thermal gradients, jitter, optical misalignments) or for speckle correction in high contrast imaging applications. The primary advantage of MEMS deformable mirrors over piezoelectric or ceramoelectric devices that are currently widely used in ground-based systems is the savings in mass, volume, and power. More actuators across a deformable mirror surface enables more precise correction, so incorporating thousands of actuators in a system compatible spacecraft SWaP constraints is advantageous. While these mirrors have been successfully demonstrated in many ground based applications, they have not been qualified nor had their performance characterized for long-duration space operations. Efforts are currently underway to perform vibration, thermal, and radiation characterization, but extended in situ demonstration is required to fully understand and characterize the behavior of these devices on orbit to enable integration of these deformable mirrors into high-contrast imaging on space telescopes. The Deformable Mirror Demonstration Mission (DeMi), is a nanosatellite that will serve as an on-orbit testbed for a MEMS deformable mirror. The mirror baselined for demonstration is a Boston Micromachines Mini (32-actuator) mirror. The payload incorporates two kinds of wavefront sensors to characterize the mirror and demonstrate low-order wavefront correction on a space-based platform. A Shack-Hartmann sensor provides high-order characterization of mirror actuation, and a focal plane imager is included to demonstrate low-order sensorless wavefront reconstruction and correction. The purpose of this research project was to design the optical payload for this nanosatellite-sized testbed and to validate the planned experiment architecture through laboratory-based hardware demonstrations (Figure 2). At the conclusion of the research project, a laboratory prototype of the optical deformable mirror demonstration payload was completed. In-house algorithms and control software are currently implemented in the setup, and a contract for a fight mission is currently being negotiated.