Open Access
19 May 2022 Forecasting wavefront corrections in an adaptive optics system
Rehan Hafeez, Finn Archinuk, Sébastien Fabbro, Hossen Teimoorinia, Jean-Pierre Véran
Author Affiliations +
Abstract

We used telemetry data from the Gemini North ALTAIR adaptive optics system to investigate how well the commands for wavefront correction (both tip/tilt and high-order turbulence) can be forecasted to reduce lag error (due to wavefront sensor averaging and computational delays) and improve delivered image quality. We showed that a high level of reduction (∼5 for tip-tilt and ∼2 for high-order modes) in the RMS wavefront error was achieved using a “forecasting filter” based on a linear autoregressive model with only a few coefficients (∼30 for tip-tilt and ∼5 for high-order modes) to complement the existing integral servo-controller. Updating this filter to adapt to evolving observing conditions is computationally inexpensive and requires <10  s of telemetry data. We also used several machine learning models (long-short term memory and dilated convolutional models) to evaluate whether further improvements could be achieved with a more sophisticated nonlinear model. Our attempts showed no perceptible improvements over linear autoregressive predictions, even for large lags in which residuals from the linear models are high, suggesting that nonlinear wavefront distortions for ALTAIR at the Gemini North telescope may not be forecasted with the current setup.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.
Rehan Hafeez, Finn Archinuk, Sébastien Fabbro, Hossen Teimoorinia, and Jean-Pierre Véran "Forecasting wavefront corrections in an adaptive optics system," Journal of Astronomical Telescopes, Instruments, and Systems 8(2), 029003 (19 May 2022). https://doi.org/10.1117/1.JATIS.8.2.029003
Received: 22 November 2021; Accepted: 29 April 2022; Published: 19 May 2022
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CITATIONS
Cited by 5 scholarly publications.
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KEYWORDS
Adaptive optics

Actuators

Autoregressive models

Wavefronts

Data modeling

Atmospheric turbulence

Turbulence

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