high-contrast imaging; optical propagation; noncommon path aberrations; extremely large telescope; Mid-infrared ELT Imager and Spectrograph
Abstract :
[en] (METIS), one of the first-generation instruments of the upcoming ELT, is designed toward the direct detection of exoplanets, using high-contrast imaging (HCI) techniques. However, it is well known that noncommon path aberrations (NCPA) limit HCI performance. In particular, quasi-static NCPA creates speckles that evolve on the same time scale as angular differential imaging (ADI) sequences, which are typically used to estimate and subtract the stellar speckle field. It is therefore crucial to model NCPA correctly during the instrument design phase to derive requirements on wavefront control algorithms that minimize their effects. We explore the chromatic beam wander caused by atmospheric refraction on METIS as a source of time-variable NCPA and its impact on HCI performance. We study the vortex coronagraph case, which is expected to set the requirements for NCPA correction. We propagate wavefronts through a model of the full METIS instrument in pupil tracking mode, taking into account the contribution of each optical element to phase aberrations in the presence of chromatic beam wander. We also model the associated amplitude aberrations that develop upon propagation. The beams are propagated within a 4-h interval, from which we extract a 1-h observing sequence close to the zenith as a representative ADI sequence. We show that the time-variable NCPA created by chromatic beam wander already reaches, and
sometimes exceeds, the allocated NCPA budget within METIS, even though its effect is smaller than the effect of water vapor seeing at N-band. A closed-loop correction is needed to compensate for their effect, but even so, the HCI performance may be limited by the associated amplitude aberrations, which cannot be corrected within METIS.
Research Center/Unit :
STAR - Space sciences, Technologies and Astrophysics Research - ULiège
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Boné, André
Delacroix, Christian ; Université de Liège - ULiège > Département d'astrophysique, géophysique et océanographie (AGO) > Planetary & Stellar systems Imaging Laboratory
Absil, Olivier ; Université de Liège - ULiège > Unités de recherche interfacultaires > Space sciences, Technologies and Astrophysics Research (STAR)
Language :
English
Title :
Simulating the effect of chromatic beam wander on the ELT/METIS high-contrast imaging performance
Publication date :
12 January 2026
Journal title :
Journal of Astronomical Telescopes, Instruments, and Systems
F.R.S.-FNRS - Belgian National Fund for Scientific Research ERC - European Research Council European Union
Commentary :
Copyright 2026 Society of Photo‑Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this publication for a fee or for commercial purposes, and modification of the contents of the publication are prohibited.
S. Ramsay et al., “Instrumentation for ESO’s extremely large telescope,” The Messenger 182, 3–6 (2021).https://doi.org/10.18727/0722-6691/5214
B. R. Brandl et al., “Status update on the development of METIS, the mid-infrared ELT imager and spectrograph,” Proc. SPIE 12184, 1218421 (2022).PSISDG 0277-786X https://doi.org/10.1117/12.2628331
R. Bowens et al., “Exoplanets with ELT-METIS. I. Estimating the direct imaging exoplanet yield around stars within 6.5 parsecs,” Astron. Astrophys. 653, A8 (2021).https://doi.org/10.1051/0004-6361/202141109
B. Carlomagno et al., “METIS high-contrast imaging: design and expected performance,” J. Astron. Telesc. Instrum. Syst. 6, 035005 (2020).https://doi.org/10.1117/1.JATIS.6.3.035005
C. Delacroix et al., “The High-contrast End-to-End Performance Simulator (HEEPS): influence of ELT/METIS instrumental effects,” Proc. SPIE 12187, 121870F (2022).PSISDG 0277-786X https://doi.org/10.1117/12.2630341
S. Hippler et al., “Single conjugate adaptive optics for the ELT instrument METIS,” Exp. Astron. 47, 65–105 (2019).https://doi.org/10.1007/s10686-018-9609-y
M. Feldt et al., “High strehl and high contrast for the ELT instrument METIS: Final design, implementation, and predicted performance of the single-conjugate adaptive optics system,” Exp. Astron. 58, 20 (2024).https://doi.org/10.1007/s10686-024-09968-2
R. Galicher and J. Mazoyer, “Imaging exoplanets with coronagraphic instruments,” arXiv:2302.10833 (2023).
C. Marois et al., “Angular differential imaging: a powerful high-contrast imaging technique,” Astrophys. J. 641, 556–564 (2006).https://doi.org/10.1086/500401
F. Cantalloube et al., “Peering through SPHERE images: a glance at contrast limitations,” The Messenger 176, 25–31 (2019).https://doi.org/10.18727/0722-6691/5138
N. Jovanovic et al., “Review of high-contrast imaging systems for current and future ground-based and space-based telescopes: Part II. Common path wavefront sensing/control and coherent differential imaging,” Proc. SPIE 10703, 107031U (2018).PSISDG 0277-786X https://doi.org/10.1117/12.2314260
E. Huby et al., “Post-coronagraphic tip-tilt sensing for vortex phase masks: the QACITS technique,” Astron. Astrophys. 584, A74 (2015).https://doi.org/10.1051/0004-6361/201527102
F. Martinache, “The asymmetric pupil Fourier wavefront sensor,” Publ. Astron. Soc. Pac. 125, 422 (2013).https://doi.org/10.1086/670670
S. P. Bos et al., “Focal-plane wavefront sensing with the vector-Apodizing Phase Plate,” Astron. Astrophys. 632, A48 (2019).https://doi.org/10.1051/0004-6361/201936062
G. Orban de Xivry et al., “ALF: an asymmetric Lyot wavefront sensor for the ELT/METIS vortex coronagraph,” Proc. SPIE 13097, 130973Z (2024).PSISDG 0277-786X https://doi.org/10.1117/12.3019159
O. Absil et al., “Impact of water vapor seeing on mid-infrared high-contrast imaging at ELT scale,” Proc. SPIE 12185, 1218511 (2022).https://doi.org/10.1117/12.2627972
M. A. Kenworthy et al., “A review of high contrast imaging modes for METIS,” Proc. SPIE 10702, 10702A3 (2018).PSISDG 0277-786X https://doi.org/10.1117/12.2314066
O. Absil et al., “METIS high-contrast imaging: from final design to manufacturing and testing,” Proc. SPIE 13096, 1309652 (2024).PSISDG 0277-786X https://doi.org/10.1117/12.3019692
D. Mawet et al., “Fundamental limitations of high contrast imaging set by small sample statistics,” Astrophys. J. 792, 97 (2014).ASJOAB 0004-637X https://doi.org/10.1088/0004-637X/792/2/97
T. Agócs et al., “Preliminary optical design for the common fore optics of METIS,” Proc. SPIE 9908, 99089Q (2016).PSISDG 0277-786X https://doi.org/10.1117/12.2232512
T. Agócs et al., “End to end optical design and wavefront error simulation of METIS,” Proc. SPIE 10702, 107029O (2018).PSISDG 0277-786X https://doi.org/10.1117/12.2313434
S. E. Urban and P. K. Seidelmann, Explanatory Supplement to the Astronomical Almanac, ch. “Refraction - Numerical Integration,” Section 3.281, pp. 141–143, University Science Books, Mill Valley (1992).
C. Y. Hohenkerk and A. T. Sinclair, “The computation of angular atmospheric refraction at large zenith angles,” tech. rep., Royal Greenwich Observatory Science and Engineering Research Council (1985).
C. Schmid et al., “ESO-254547 – common requirements for E-ELT instruments,” ESO internal document (2015).
J. E. Krist, “PROPER: an optical propagation library for IDL,” Proc. SPIE 6675, 66750P (2007).https://doi.org/10.1117/12.731179
G. N. Lawrence, “Optical modeling,” Appl. Opt. Opt. Eng. 11, 125 (1992).
A. Boné et al., “The Talbot effect’s impact on the high contrast imaging modes of METIS,” Proc. SPIE 11451, 114514D (2020).https://doi.org/10.1117/12.2570380
M. Lewińska-Maresca et al., “Development and verification of the largest cryogenic mid IR aluminium concave mirror for METIS showing excellent wavefront performance,” Proc. SPIE 12188, 121881P (2022).https://doi.org/10.1117/12.2629984
D. Zaalberg et al., “Development of an aluminium mirror with a novel integrated flexure-based mount for METIS cryogenic environment,” Proc. SPIE 12188, 121881O (2022).https://doi.org/10.1117/12.2629995
H. Talbot, “LXXVI. Facts relating to optical science. No. IV,” Lond. Edinburgh, Dublin Philos. Mag. J. Sci. 9(56), 401–407 (1836).https://doi.org/10.1080/14786443608649032
D. Gratadour et al., “COMPASS: an efficient, scalable and versatile numerical platform for the development of ELT AO systems,” Proc SPIE 9148, 91486O (2014).https://doi.org/10.1117/12.2056358
A. Boné et al., “The MICADO first light imager for the ELT: a comprehensive tolerance analysis for the relay optics,” Proc. SPIE 12184, 1218435 (2022).https://doi.org/10.1117/12.2629204
F. Biondi et al., “Verification strategy for the MICADO cold optics,” Proc. SPIE 12188, 121883P (2022).https://doi.org/10.1117/12.2628916
N. A. Thatte et al., “HARMONI: first light spectroscopy for the ELT: instrument final design and quantitative performance predictions,” Proc. SPIE 11447, 114471W (2020).https://doi.org/10.1117/12.2562144
Á. Menduiña-Fernández, M. Tecza and N. Thatte, “HARMONI: first light spectroscopy for the ELT: novel techniques for the calibration of non-common path aberrations,” Proc. SPIE 11447, 114472L (2020).PSISDG 0277-786X https://doi.org/10.1117/12.2560994
A. Hours et al., “HARMONI at ELT: a Zernike wavefront sensor for the high-contrast module: testbed results with realistic observation conditions,” Proc. SPIE 12185, 121852E (2022).PSISDG 0277-786X https://doi.org/10.1117/12.2627291
