Large Binocular Telescope Adaptive Optics System: New achievements and perspectives in adaptive optics

TL;DR

The LBT AO system achieved unprecedented on-sky performance with high-resolution imaging and high Strehl ratios, prompting a reevaluation of guide star strategies for future large telescopes.

Contribution

This paper reports the first on-sky performance of the LBT AO system with innovative components, demonstrating superior imaging quality and comparing guide star technologies.

Findings

Achieved 40mas resolution and >80% Strehl ratio in H band.

Images showed contrast as high as 10^-4.

Performance comparison suggests rethinking guide star roles.

Abstract

The Large Binocular Telescope (LBT) is a unique telescope featuring two co-mounted optical trains with 8.4m primary mirrors. The telescope Adaptive Optics (AO) system uses two innovative key components, namely an adaptive secondary mirror with 672 actuators and a high-order pyramid wave-front sensor. During the on-sky commissioning such a system reached performances never achieved before on large ground-based optical telescopes. Images with 40mas resolution and Strehl Ratios higher than 80% have been acquired in H band (1.6 micron). Such images showed a contrast as high as 10e-4. Based on these results, we compare the performances offered by a Natural Guide Star (NGS) system upgraded with the state-of-the-art technology and those delivered by existing Laser Guide Star (LGS) systems. The comparison, in terms of sky coverage and performances, suggests rethinking the current role ascribed to NGS and LGS in the next generation of AO systems for the 8-10 meter class telescopes and Extremely Large Telescopes (ELTs).