Various Wavefront Sensing and Control Developments on the Santa Cruz Extreme AO Laboratory (SEAL) Testbed

TL;DR

This paper reports on three wavefront sensing and control advancements at the SEAL testbed, aiming to improve high contrast imaging of exoplanets by reducing wavefront errors and speckles.

Contribution

It introduces novel developments in multi-WFS SCAO, pupil chopping for focal plane sensing, and enhanced linearity of Pyramid WFS, advancing adaptive optics capabilities.

Findings

Multi-WFS SCAO with FAST and Shack Hartmann WFS demonstrated.

Pupil chopping techniques with amplitude modulator and DM as phase modulator explored.

Enhanced linearity of non-modulated Pyramid WFS shown in laboratory tests.

Abstract

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 lower-mass, 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.