The deformable mirror demonstration mission (DeMi) CubeSat: optomechanical design validation and laboratory calibration

Abstract

Coronagraphs on future space telescopes will require precise wavefront correction to detect Earth-like exoplanets near their host stars. High-actuator count microelectromechanical system (MEMS) deformable mirrors provide wavefront control with low size, weight, and power. The Deformable Mirror Demonstration Mission (DeMi) payload will demonstrate a 140 actuator MEMS Deformable Mirror (DM) with 5.5 µm maximum stroke. We present the flight optomechanical design, lab tests of the flight wavefront sensor and wavefront reconstructor, and simulations of closed-loop control of wavefront aberrations. We also present the compact flight DM controller, capable of driving up to 192 actuator channels at 0-250V with 14-bit resolution. Two embedded Raspberry Pi 3 compute modules are used for task management and wavefront reconstruction. The spacecraft is a 6U CubeSat (30 cm x 20 cm x 10 cm) and launch is planned for 2019.

Laser Guide Star for Large Segmented-aperture Space Telescopes. I. Implications for Terrestrial Exoplanet Detection and Observatory Stability

“…Such "diffraction-limited" stability is well within the range of small satellite optical systems (e.g. Allan et al (2018)).…”

Optical calibration and first light for the deformable mirror demonstration mission CubeSat (DeMi)

“…More details on the DeMi optomechanical design can be found in previous publications. [1][2][3][4][5][6] The key optical design parameters are summarized in Table 1.…”

“…The Deformable Mirror Demonstration Mission (DeMi) payload is an optical instrument that is demonstrating the on-orbit performance of a 140-actuator Microelectromechanical Systems Deformable Mirror (MEMS DM) on a 6U (10 × 20 × 30 cm 3 ) CubeSat. [1][2][3][4][5][6] The key payload requirements are to measure individual DM actuator wavefront displacement contributions to a precision of 12 nm, measure low order optical aberrations to λ∕10 accuracy and λ∕50 precision, and correct both static and dynamic wavefront errors to <100 nm RMS error. The DeMi mission will raise the Technology Readiness Level (TRL) of MEMS DM technology from a five to at least a seven for future space telescope applications 7 (see the Appendix for a description of NASA TRLs).…”

MEMS Deformable Mirrors for Space-Based High-Contrast Imaging

“…The goal of this mission is to raise the Technology Readiness Level (TRL) of MEMS DM technology from a TRL of 5 to at least a TRL of 7 for future space telescope applications [107]. For a description of the DeMi optical design, see Allan et al 2018 [108]. For a description of the DM driver development, see Haughwout 2018 [20].…”

“…The DeMi optical design contains an off axis parabola-based telescope with a 50 mm primary mirror, a 140-actuator BMC Multi DM, and both an Image Plane wavefront sensor (WFS) and a Shack Hartmann WFS [108]. The Image Plane WFS captures pictures of the system Point-Spread Function (PSF) and serves as a truth sensor for wavefront correction.…”