The focal-plane assisted pyramid wavefront sensor: enabling frame-by-frame optical gains tracking

TL;DR

This paper introduces a novel focal-plane assisted pyramid wavefront sensor that enables real-time optical gains tracking, improving adaptive optics performance by mitigating non-linear behaviors with minimal flux loss.

Contribution

It proposes a new focal plane imaging method combined with a convolutive model to track pyramid wavefront sensor optical gains in real-time, addressing non-linear control issues.

Findings

Effective optical gains tracking demonstrated in simulations

Improved bootstrap and NCPA correction performance

Minimal flux required for focal plane imaging path

Abstract

With its high sensitivity, the Pyramid wavefront sensor (PyWFS) is becoming an advantageous sensor for astronomical adaptive optics (AO) systems. However, this sensor exhibits significant non-linear behaviours leading to challenging AO control issues. In order to mitigate these effects, we propose to use, in addition to the classical pyramid sensor, a focal plane image combined with a convolutive description of the sensor to perform a fast tracking of the PyWFS non-linearities, the so-called optical gains (OG). We show that this additional focal plane imaging path only requires a small fraction of the total flux, while representing a robust solution to estimate the PyWFS OG. Finally, we demonstrate the gain brought by our method with the specific examples of bootstrap and Non-Common Path Aberrations (NCPA) handling.