Impact of water vapor seeing on mid-infrared high-contrast imaging at ELT scale

Olivier Absil; Christian Delacroix; Gilles Orban de Xivry; Prashant Pathak; Matthew Willson; Philippe Berio; Roy van Boekel; Alexis Matter; Denis Defrère; Leo Burtscher; Julien Woillez; Bernhard Brandl

doi:10.1117/12.2627972

29 August 2022 Impact of water vapor seeing on mid-infrared high-contrast imaging at ELT scale

Olivier Absil, Christian Delacroix, Gilles Orban de Xivry, Prashant Pathak, Matthew Willson, Philippe Berio, Roy van Boekel, Alexis Matter, Denis Defrère, Leo Burtscher, Julien Woillez, Bernhard Brandl

Author Affiliations +

Proceedings Volume 12185, Adaptive Optics Systems VIII; 1218511 (2022) https://doi.org/10.1117/12.2627972
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Abstract

The high-speed variability of the local water vapor content in the Earth atmosphere is a significant contributor to ground-based wavefront quality throughout the infrared domain. Unlike dry air, water vapor is highly chromatic, especially in the mid-infrared. This means that adaptive optics correction in the visible or near-infrared domain does not necessarily ensure a high wavefront quality at longer wavelengths. Here, we use literature measurements of water vapor seeing, and more recent infrared interferometric data from the Very Large Telescope Interferometer (VLTI), to evaluate the wavefront quality that will be delivered to the METIS mid-infrared camera and spectrograph for the Extremely Large Telescope (ELT), operating from 3 to 13 μm, after single-conjugate adaptive optics correction in the near-infrared. We discuss how the additional wavefront error due to water vapor seeing is expected to dominate the wavefront quality budget at N band (8–13 μm), and therefore to drive the performance of mid-infrared high-contrast imaging modes at ELT scale. Then we present how the METIS team is planning to mitigate the effect of water vapor seeing using focal-plane wavefront sensing techniques, and show with end-to-end simulations by how much the high-contrast imaging performance can be improved.

Conference Presentation

Citation Download Citation

Olivier Absil, Christian Delacroix, Gilles Orban de Xivry, Prashant Pathak, Matthew Willson, Philippe Berio, Roy van Boekel, Alexis Matter, Denis Defrère, Leo Burtscher, Julien Woillez, and Bernhard Brandl "Impact of water vapor seeing on mid-infrared high-contrast imaging at ELT scale", Proc. SPIE 12185, Adaptive Optics Systems VIII, 1218511 (29 August 2022); https://doi.org/10.1117/12.2627972

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