SAXO+, the second-stage adaptive optics for SPHERE: NCPA compensation and dark hole loop with a pyramid wavefront sensor
Year: 2026
Type: conference-abstract
Abstract: The SAXO+ upgrade of the VLT/SPHERE adaptive optics system introduces a second-stage near-infrared pyra mid wavefront sensor to improve high-contrast imaging, making accurate calibration of non-common path aber rations (NCPAs) essential to fully exploit its performance. This work refines the expected level of NCPAs in SAXO+ and presents the calibration procedures developed for static NCPA compensation and focal-plane dark hole control. Monte Carlo simulations based on an updated Zemax optical model were used to estimate the NCPA error budget. These simulations are in good agreement with previous measurements on SPHERE and with the assumptions adopted in earlier performance studies. We also propose a calibration strategy that offloads most static aberration correction to the first-stage deformable mirror while preserving the second-stage mirror stroke for high-speed adaptive optics correction. These results validate the expected SAXO+ optical quality and establish the calibration framework required for efficient NCPA compensation and focal-plane wavefront control during future on-sky operations.
Source: Adaptive Optics Systems VIII
DOI: 10.1117/12.3102304
Authors: Johan Mazoyer, Charles Goulas, Raphaël Galicher, Axel Potier, Fabrice Vidal, Florian Ferreira, Arnaud Sevin, Clémentine Béchet, Isaac Bernardino Dinis, Anthony Boccaletti, Gael Chauvin, Fausto Cortecchia, Emiliano Diolaiti, Nicolas Galland, Caroline Kulcsár, Maud Langlois, Matteo Lombini, Julien Milli, Mamadou N'Diaye, Henri-François Raynaud, Laura Schreiber, Michel Tallon, Arthur Vigan, François Wildi
Institutions: Centre National de la Recherche Scientifique, Université Paris Cité, Université Paris Sciences et Lettres, Observatoire de Paris, Sorbonne Université, CY Cergy Paris Université, Lyon 1 Université, École Normale Supérieure de Lyon, Centre de Recherche Astrophysique de Lyon, University of Geneva, Max Planck Institute for Astronomy, Osservatorio di Astrofisica e Scienza dello Spazio, National Institute for Astrophysics, Université Paris-Saclay, Institut d’Optique Graduate School, Laboratoire Charles Fabry, Institut de Planétologie et d'Astrophysique de Grenoble, Université Grenoble Alpes, Lagrange Laboratory, Observatoire de la Côte d’Azur, Aix-Marseille Université
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7168294021