Ground-based high contrast imaging (HCI) and extreme adaptive optics (AO) technologies have advanced to the point of enabling direct detections of gas-giant exoplanets orbiting beyond the snow lines around nearby young star systems. However, leftover wavefront errors using current HCI and AO technologies, realized as “speckles” in the coronagraphic science image, still limit HCI instrument sensitivities to detecting and characterizing lowermass, closer-in, and/or older/colder exoplanetary systems. Improving the performance of AO wavefront sensors (WFSs) and control techniques is critical to improving such HCI instrument sensitivity. Here we present three different ongoing wavefront sensing and control project developments on the Santa cruz Extreme AO Laboratory (SEAL) testbed: (1) “multi-WFS single congugate AO (SCAO)” using the Fast Atmospheric Self-coherent camera (SCC) Technique (FAST) and a Shack Hartmann WFS, (2) pupil chopping for focal plane wavefront sensing, first with an external amplitude modulator and then with the DM as a phase-only modulator, and (3) a laboratory demonstration of enhanced linearity with the non-modulated bright Pyramid WFS (PWFS) compared to the regular PWFS. All three topics share a common theme of multi-WFS SCAO and/or second stage AO, presenting opportunities and applications to further investigate these techniques in the future.
KAUST Repository Item: Exported on 2022-10-25
Acknowledgements: We gratefully acknowledge research support of the University of California Observatories and UCSC’s Lamat NSF REU program for funding this research. This work also benefited from the 2022 Exoplanet Summer Program in the Other Worlds Laboratory (OWL) at the University of California, Santa Cruz, a program funded by the Heising-Simons Foundation. Author B. Gerard thanks the 2018 SCExAO team for hosting discussions that led to the pupil chopping concept and the UCSC LAO group, particularly Dominic Sanchez, for discussions that led to the DM-based pupil chopping idea.