Redundant apodization for direct imaging of exoplanets

Leboulleux, Lucie; Carlotti, Alexis; N’Diaye, Mamadou

doi:10.1051/0004-6361/202142410

Cited by 3 publications

(10 citation statements)

References 36 publications

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“…Moreover, Hutterer et al (2018) proposes a split approach with a separated reconstruction of petal-level pistons and of other modes using Bayesian statistics. This paper investigates a different mitigation strategy, with an adaptation of the RAP design proposed in Leboulleux et al (2022). All the island effects mentioned earlier will later be considered as differential pistons between petals, with tips and tilts in the low-wind effect case, and with a quite slow dynamic evolution (one to a few seconds).…”

Section: Low-wind Effect and Petaling Effectmentioning

confidence: 99%

“…The RAP concept (Leboulleux et al 2022) consists of apodizing each segment to dig a dark hole in the low-order envelope. Since the image corresponding to the full segment pupil is proportional to the segment PSF, it also deepens the contrast in the segmented pupil coronagraphic PSF.…”

Section: Review Of Redundant Apodized Pupilsmentioning

confidence: 99%

“…In Leboulleux et al (2022), the RAP concept is applied on errors due to the segmentation of the primary-mirror, on a Giant Magellan telescope-like pupil combined with an Apodized Pupil Lyot Coronagraph (APLC) (e.g., Soummer et al 2009;N'Diaye et al 2015b;Zimmerman et al 2016) on one hand and with an Apodizing Phase Plate (APP) (e.g., Codona 2007;Kenworthy et al 2010;Carlotti 2013;Por 2017) coronagraph on the other hand. RAPs deliver an increased robustness albeit at more modest angular separations than targeted by exo-Earth-imagers.…”

Section: Review Of Redundant Apodized Pupilsmentioning

confidence: 99%

“…The apodization problem consists of minimizing the intensity in the defined dark region by exploring the parameter space of the petal apodization while maximizing the throughput of the final apodizer. As in Leboulleux et al (2022), it is formulated in AMPL (A Mathematical Programming Language) (Fourer et al 2002), and the procedure then calls the Gurobi solver to find the optimal solution (Gurobi Optimization, LLC 2021). On the HCM of HARMONI, two designs have been selected: HSP1 and HSP2 (see Fig.…”

Section: Review Of Redundant Apodized Pupilsmentioning

confidence: 99%

“…In this paper, we propose to adapt the pupil apodization according to its segmentation by the spiders to make it robust to differential piston, tip, and tilt errors between the pupil petals. This concept derives from the Redundant Apodized Pupil (RAP) coronagraphs, developed and tested in Leboulleux et al (2022), albeit for primary mirror segmentation-due errors. In section 2, we summarize the island effects expected on the ELT.…”

Section: Introductionmentioning

confidence: 99%

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Redundant apodization for direct imaging of exoplanets 2: Application to island effects

Leboulleux,

Carlotti,

N'Diaye

et al. 2022

Preprint

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Context. Telescope pupil fragmentation from spiders generates specific aberrations that have been observed at various telescopes and are expected on the 30+-meter class telescopes under construction. This so-called island effect induces differential pistons, tips and tilts on the pupil petals, deforming the instrumental point spread function (PSF), and is one of the main limitation to the direct detection of exoplanets with high-contrast imaging. These petal-level aberrations can have different origins such as the low-wind effect or petaling errors in the adaptive optics reconstruction. Aims. In this paper, we propose to alleviate the impact of the aberrations induced by island effects on high-contrast imaging by adapting the coronagraph design in order to increase its robustness to petal-level aberrations. Methods. Following a method first developed and applied on robustness to errors due to primary mirror segmentation (segment phasing errors, missing segments...), we develop and test Redundant Apodized Pupils (RAP), i.e. apodizers designed at the petalscale, then duplicated and rotated to mimic the pupil petal geometry. Results. We apply this concept to the ELT architecture, made of six identical petals, to yield a 10 −6 contrast in a dark region from 8 to 40λ/D. Both amplitude and phase apodizers proposed in this paper are robust to differential pistons between petals, with minimal degradation to their coronagraphic PSFs and contrast levels. In addition, they are also more robust to petal-level tip-tilt errors than classical apodizers designed for the whole pupil, with which the limit of contrast of 10 −6 in the coronagraph dark zone is achieved for constraints up to 2 rad RMS of these petal-level modes. Conclusions. In this paper, the RAP concept proves its robustness to island effects (low-wind effect and post-adaptive optics petaling), with an application to the ELT architecture. It can also be considered for other 8-to 30-meter class ground-based units such as VLT/SPHERE, Subaru/SCExAO, GMT/GMagAO-X, or TMT/PSI.

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Section: Low-wind Effect and Petaling Effectmentioning

confidence: 99%

Section: Review Of Redundant Apodized Pupilsmentioning

confidence: 99%

Section: Review Of Redundant Apodized Pupilsmentioning

confidence: 99%

Section: Review Of Redundant Apodized Pupilsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Redundant apodization for direct imaging of exoplanets 2: Application to island effects

Leboulleux,

Carlotti,

N'Diaye

et al. 2022

Preprint

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Redundant apodization for direct imaging of exoplanets

Leboulleux

Carlotti

N’Diaye

et al. 2022

A&A

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Context. Telescope pupil fragmentation from spiders generates specific aberrations that have been observed at various telescopes and are expected on the 30-meter class telescopes under construction. This is known as the island effect, and it induces differential pistons, tips, and tilts on the pupil petals, deforming the instrumental point spread function (PSF); it is one of the main limitations to the direct detection of exoplanets with high-contrast imaging. These petal-level aberrations can have different origins such as the low-wind effect or petaling errors in the adaptive optics reconstruction. Aims. In this paper we propose a method for alleviating the impact of the aberrations induced by island effects on high-contrast imaging by adapting the coronagraph design in order to increase its robustness to petal-level aberrations. Methods. Following a method first developed and applied on robustness to errors due to primary mirror segmentation (e.g., segment phasing errors, missing segments), we developed and tested redundant apodized pupils (RAP): apodizers designed at the petal-scale, then duplicated and rotated to mimic the pupil petal geometry. Results. We applied this concept to the ELT architecture, made of six identical petals, to yield a 10 −6 contrast in a dark region from 8 to 40λ/D. Both amplitude and phase apodizers proposed in this paper are robust to differential pistons between petals, with minimal degradation to their coronagraphic PSFs and contrast levels. In addition, they are also more robust to petal-level tip-tilt errors than classical apodizers designed for the whole pupil, with which the limit of contrast of 10 −6 in the coronagraph dark zone is achieved for constraints up to 2 rad RMS of these petal-level modes. Conclusions. In this paper the RAP concept proves its robustness to island effects (low-wind effect and post-adaptive optics petaling), with an application to the ELT architecture. It can also be considered for other 8-to 30-meter class ground-based units such as VLT/SPHERE, Subaru/SCExAO, GMT/GMagAO-X, and TMT/PSI.

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Interferometric apodization by homothety – I. Optimization of the device parameters

Chafi

Azhari

Azagrouze

et al. 2023

Monthly Notices of the Royal Astronomical Society

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This study is focused on the very high dynamic imaging field, specifically the direct observation of exoplanetary systems. The coronagraph is an essential technique for suppressing the star’s light, making it possible to detect an exoplanet with a very weak luminosity compared to its host star. Apodization improves the rejection of the coronagraph, thereby increasing its sensitivity. This work presents the apodization method by interferometry using homothety, with either a rectangular or circular aperture. We discuss the principle method, the proposed experimental setup, and present the obtained results by optimizing the free parameters of the system while concentrating the maximum of the light energy in the central diffraction lobe, with a concentration rate of 93.6% for the circular aperture and 91.5% for the rectangular geometry. The obtained results enabled scaling the various elements of the experiment in accordance with practical constraints. Simulation results are presented for both circular and rectangular apertures. We performed simulations on a hexagonal aperture, both with and without a central obstruction, as well as a segmented aperture similar to the one used in the Thirty Meter Telescope (TMT). This approach enables the attainment of a contrast of approximately 10−4 at small angular separations, specifically around 1.8λ/D. When integrated with a coronagraph, this technique exhibits great promise. These findings confirm that our proposed technique can effectively enhance the performance of a coronagraph.

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Redundant apodization for direct imaging of exoplanets

Cited by 3 publications

References 36 publications

Redundant apodization for direct imaging of exoplanets 2: Application to island effects

Redundant apodization for direct imaging of exoplanets 2: Application to island effects

Redundant apodization for direct imaging of exoplanets

Interferometric apodization by homothety – I. Optimization of the device parameters

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