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

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.

References in corpus (5)

• Limits of Adaptive Optics for high contrast imaging
• General formalism for Fourier based Wave Front Sensing
• Pyramid wavefront sensor optical gains compensation using a convolutional model
• Kernel formalism applied to Fourier based wave front sensing in presence of residual phases
• Adaptive optics with programmable Fourier-based wavefront sensors: a spatial light modulator approach to the LOOPS testbed

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• Expected performance of the Pyramid wavefront sensor with a laser guide star for 40 m class telescopes
• RISTRETTO: a VLT XAO design to reach Proxima Cen b in the visible