First Experimental Results of the Fast Atmospheric Self-coherent Camera Technique on the Santa cruz Extreme Adaptive optics Laboratory Testbed: Demonstration of High Speed Focal Plane Wavefront Control of Residual Atmospheric Speckles

TL;DR

This paper presents initial experimental validation of the FAST technique, a high-speed focal plane wavefront control method, demonstrating its ability to suppress evolving atmospheric speckles in real-time for improved exoplanet imaging.

Contribution

The paper introduces the FAST algorithm and demonstrates its effectiveness in real-time atmospheric speckle suppression on a laboratory testbed.

Findings

FAST achieves millisecond-timescale wavefront control.

FAST effectively compensates for residual atmospheric turbulence.

Experimental results show improved speckle suppression.

Abstract

Current and future high contrast imaging instruments aim to detect exoplanets at closer orbital separations, lower masses, and/or older ages than their predecessors, with the eventual goal of directly detecting terrestrial-mass habitable-zone exoplanets. However, continually evolving speckles in the coronagraphic science image still limit state-of-the-art ground-based exoplanet imaging instruments to contrasts at least two orders of magnitude worse than what is needed to achieve this goal. For ground-based adaptive optics (AO) instruments it remains challenging for most speckle suppression techniques to attenuate both the dynamic atmospheric and quasi-static instrumental speckles. We have proposed a focal plane wavefront sensing and control algorithm to address this challenge, called the Fast Atmospheric Self-coherent camera (SCC) Technique (FAST), which enables the SCC to operate down to millisecond timescales even when only a few photons are detected per speckle. Here we present preliminary experimental results of FAST on the Santa Cruz Extreme AO Laboratory (SEAL) testbed. In particular, we illustrate the benefit "second stage" AO-based focal plane wavefront control, demonstrating FAST closed-loop compensation of evolving residual atmospheric turbulence on millisecond-timescales.