Fourier Filtering wave-front sensing for adaptive optics

Monday, 12 December 2022 7 a.m. — 8 a.m. MST

AURA Lecture Hall

NOIRLab South Colloquia
Mahawa Cissé (Laboratoire d'Astrophysique de Marseille)

The 21st century marks a new era in astronomy with the construction of giant telescopes. The Extremely Large Telescope (ELT) will be the largest telescope ever built with a primary mirror of 39m diameter. The ELT gathers 20 times more light than a single Unit Telescope of the Very Large Telescope (VLT). Because of its gigantic primary mirror, the ELT pupil will be fragmented. This typical structure of the next generation of telescopes will bring new type of aberrations that need to be corrected. In addition of these new aberrations, we also need to consider the atmospheric turbulence that will affect the angular resolution of the telescope. 

Therefore, the advent of the giant telescopes is a new challenge for Adaptive Optics (AO) to correct both the atmospheric turbulence and the aberration induced by the telescope itself.

The quality of the AO correction depends mainly on the measurements done by the Wave-Front Sensor (WFS). To achieve a near-diffraction image quality, the measurement of the WFS must be as accurate as possible. Due to their high sensitivity compared to the Shack-Hartmann (SH), the Fourier Filtering class (FFWFS) such as the Pyramid WFS (PWFS) or the Zernike mask (ZWFS) appear to be a viable solution.