Experimental verification of NN and PCA for NCPA mitigation

A. Terreri; F. Pedichini; M. Kasper; T. C. Heritier; B. Engler; M. Stangalini; D. Del Moro; R. Briguglio; G. Li Causi; M. Mattioli; R. Piazzesi; G. Viavattene; S. Antoniucci; V. Testa; M. Gangi

doi:10.1117/12.2629249

29 August 2022 Experimental verification of NN and PCA for NCPA mitigation

A. Terreri, F. Pedichini, M. Kasper, T. C. Heritier, B. Engler, M. Stangalini, D. Del Moro, R. Briguglio, G. Li Causi, M. Mattioli, R. Piazzesi, G. Viavattene, S. Antoniucci, V. Testa, M. Gangi

Author Affiliations +

Proceedings Volume 12185, Adaptive Optics Systems VIII; 1218587 (2022) https://doi.org/10.1117/12.2629249
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Conference Poster

Abstract

All the aberrations not corrected by Adaptive Optics (AO) systems are important limitations for high contrast imaging at large telescopes. Among them, the most relevant ones are called Non-Common Path Aberrations (NCPA): these are present downstream of the separation of the optical paths to Wavefront Sensor and scientific focal plane. The typical approach to mitigate them is to set an offset on the AO system with the opposite sign of this NCPA. It can be obtained with a trial-and-error approach or with sophisticated focal plane Wavefront sensing. There is a need for a fast procedure to measure NCPA in order to limit the telescope downtime and to repeat, if needed, the correction procedure to cope with any temporal variation. Different methods exists to measure and compensate it introducing the correction as offset in the AO control loop. New approaches based on Neural Networks (NNs) have also been proposed. In this work, using simulated images, we test and describe the application of a supervised Multi-layer Perceptron (MLP) NN for the mitigation of NCPA in high contrast imaging at visible wavelengths. As shown in our previous work, we already tested the method on simulated images and showed that this method is robust even in the presence of turbulence-induced dynamic aberrations that are not labelled in the training phase of the NN corresponding to the typical AO residual of the daytime calibration. We tested the method on the GHOST optical test bench at ESO laboratories and preliminary results show the method is very promising, recovering almost completely the SR in an iterative correction process.

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A. Terreri, F. Pedichini, M. Kasper, T. C. Heritier, B. Engler, M. Stangalini, D. Del Moro, R. Briguglio, G. Li Causi, M. Mattioli, R. Piazzesi, G. Viavattene, S. Antoniucci, V. Testa, and M. Gangi "Experimental verification of NN and PCA for NCPA mitigation", Proc. SPIE 12185, Adaptive Optics Systems VIII, 1218587 (29 August 2022); https://doi.org/10.1117/12.2629249

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