Visible near-diffraction limited lucky imaging with full-sky laser assisted adaptive optics

TL;DR

This paper presents a novel technique combining lucky imaging with laser guide star adaptive optics, achieving near-diffraction limited imaging across the entire sky without natural guide stars, demonstrated through Monte Carlo simulations.

Contribution

The authors introduce a new method integrating lucky imaging with tomographic laser guide star adaptive optics, enabling full sky coverage and improved image quality on large telescopes.

Findings

Achieves up to 35% Strehl ratio in 0.7 arcsecond seeing conditions.

Provides full sky-coverage adaptive optics correction without natural guide stars.

Suitable for faint reference stars down to Magnitude 18 and beyond.

Abstract

Both lucky imaging techniques and adaptive optics require natural guide stars, limiting sky coverage, even when laser guide stars are used. Lucky imaging techniques become less successful on larger telescopes unless adaptive optics is used, as the fraction of images obtained with well behaved turbulence across the whole telescope pupil becomes vanishingly small. Here, we introduce a technique combining lucky imaging techniques with tomographic laser guide star adaptive optics systems on large telescopes. This technique does not require any natural guide star for the adaptive optics, and hence offers full sky-coverage adaptive optics correction. In addition, we introduce a new method for lucky image selection based on residual wavefront phase measurements from the adaptive optics wavefront sensors. We perform Monte-Carlo modelling of this technique, and demonstrate I-band Strehl ratios of up to 35% in 0.7~arcsecond mean seeing conditions with 0.5~m deformable mirror pitch and full adaptive optics sky-coverage. We show that this technique is suitable for use with lucky imaging reference stars as faint as Magnitude 18, and fainter if more advanced image selection and centring techniques are used.