Direct imaging of an Earth-like exoplanet requires starlight suppression with a contrast ratio on the order of 1 × 10 −10 at small angular separations of 100 milliarcseconds or less in visible light with more than 50 nm bandwidth. To our knowledge, the technology needed to achieve the contrast and stability has not been demonstrated as of January 2019. The science requirements for near future National Aeronautics and Space Administration (NASA) missions such as James Webb Space Telescope (JWST)'s Near Infrared Camera (NIRCam) coronagraph and Wide-Field InfraRed Survey Telescope (WFIRST) Coronagraph Instrument (CGI) are at least 10 times short. To investigate and guide the technology to reach this capability, we built a high contrast coronagraph testbed at NASA's Jet Propulsion Laboratory (JPL). Titled the Decadal Survey Testbed (DST), this state-of-art testbed is based on the accumulated experience of JPL's High Constrast Imaging Testbed (HCIT) team. Currently, the DST hosts a Hybrid Lyot Coronagraph (HLC) with an unobscured, circular pupil. The DST also has two deformable mirrors and is equipped with the Low Order Wavefront Sensing and Control (LOWFS/C) subsystem to sense and correct the dynamic wavefront disturbances. In this paper, we present up-to-date progress of the testbed demonstration. As of January 2019, we repeatedly obtain convergence below 4 × 10 −10 mean contrast with 10% broadband light centered at 550 nm in a 360 degrees dark hole with a working angle between 3 λ/D and 8 λ/D. We show the key elements used in the testbed and the performance results with associated analysis.

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This paper presents a concept for ultralightweight deformable mirrors, based on a thin substrate of optical surface quality, coated with continuous active layers that provide separate modes of actuation at different length scales. This concept eliminates any kind of stiff backing structure for the mirror surface and exploits microfabrication technologies to provide tight integration of the active materials into the mirror structure, to avoid actuator print-through effects. Proof-of-concept, 10 cm diameter mirrors with an areal density of 0.6 kg∕m 2 have been designed, built, and tested to measure their shape-correction performance and verify the finite-element models used for design. The low-cost manufacturing scheme involves low-temperature processing steps (below 140°C) to minimize residual stresses, does not require precision photolithography, and is therefore scalable to larger diameters depending on application requirements.

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