Polynomial Apodizers for Centrally Obscured Vortex Coronagraphs

Fogarty, Kevin; Pueyo, Laurent; Mazoyer, J.; N’Diaye, Mamadou

doi:10.3847/1538-3881/aa9063

Cited by 18 publications

(30 citation statements)

References 52 publications

(71 reference statements)

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“…The charge 4 vortex have a very small advantages at very small separation over the charge 6. However, at large separations, the charge 6 PAVC almost doubles the performance in throughput of the charge 4 RAVC, as expected from Fogarty et al (2017b).…”

Section: Impact Of the Static Coronagraphsupporting

confidence: 59%

“…Size of the Lyot stop radius with the WFIRST aperture Some coronagraph designs (APLC, PAVC) provide the possibility of choosing the inner and outer radius of the Lyot stop and to optimize the apodization for this Lyot Stop. In N'Diaye et al (2015) and Fogarty et al (2017b), the authors explore the parameter space of these parameters to maximize the throughput in the final focal plane. Since the optimization of this parameter for each coronagraph has been done in previous papers N' Diaye et al (2016) and Fogarty et al (2017b), we only focus of its impact on the ACAD-OSM method performance.…”

Section: Impact Of the Static Coronagraphmentioning

confidence: 99%

“…This formalism has been developed to understand the limitations of the two DM aperture discontinuity correction, but is not specific to the ACAD-OSM correction algorithm and can be applied to any two DM correction algorithms, such as the ones used for correction of phase and amplitude aberrations Beaulieu et al 2017) or the active technique developed for the WFIRST instrument (Krist 2016). It can also be useful for fixed mirror apodization techniques (Guyon 2005;Guyon et al 2014;Fogarty et al 2017b), as long as they introduce small enough apodization (as defined in Mazoyer et al 2016) and can therefore be simulated using the Fresnel assumptions.…”

Section: Robustness To Small Tt Jittermentioning

confidence: 99%

“…For this coronagraph, the size of the Lyot stop inner radius is measured using the analytic method developed in Mawet et al (2013), which drastically limits the throughput for the charge 4 coronagraph. For this reason, a third coronagraph is used in this study, a charge 6 polynomial apodized vortex coronagraph (PAVC, Fogarty et al 2017b). This coronagraph also uses a vortex FPM in focal plane, but uses a different apodization.…”

Section: Impact Of the Static Coronagraphmentioning

confidence: 99%

“…Several static (e.g relying on printed phase/amplitude masks in the pupil/image plane of the instrument) coronagraph solutions have been proposed over the past few years: APLC (Apodized pupil Lyot coronagraph, Soummer et al 2007; N' Diaye et al 2016), PIAACMC (PhaseInduced Amplitude Apodization complex mask coronagraph, Guyon et al 2005Guyon et al , 2014, or apodized Vortex (Ruane et al 2016;Fogarty et al 2017b). We chose another approach and introduced a new technique, Active Correction of Aperture Discontinuities -Optimized Stroke Minimization (ACAD-OSM), in a previous paper -hereafter ACAD-OSM I.…”

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confidence: 99%

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Active Correction of Aperture Discontinuities-Optimized Stroke Minimization. II. Optimization for Future Missions

Mazoyer

Pueyo

N’Diaye

et al. 2017

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High-contrast imaging and spectroscopy provide unique constraints for exoplanet formation models as well as for planetary atmosphere models. Instrumentation techniques in this field have greatly improved over the last two decades, with the development of stellar coronagraphy, in parallel with specific methods of wavefront sensing and control. Next generation space-and ground-based telescopes will allow the characterization cold solar-system like planets for the first time and maybe even in situ detection of bio-markers. However, the growth of primary mirror diameters, necessary for these detection, comes with an increase of their complexity (segmentation, secondary mirror features). These discontinuities in the aperture can greatly limit the performance of coronagraphic instruments. In this context, we introduced a new technique, Active Correction of Aperture Discontinuities -Optimized Stroke Minimization (ACAD-OSM), to correct for the diffractive effects of aperture discontinuities in the final image plane of a coronagraph, using deformable mirrors. In this paper, we present several tools that can be used to optimize the performance of this technique for its application to future large missions. In particular, we analyze the influence of the deformable setup (size and separating distance) and found that there is an optimal point for this setup, optimizing the performance of the instrument in contrast and throughput while minimizing the strokes applied to the deformable mirrors. These results will help us design future coronagraphic instruments to obtain the best performance.

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Section: Impact Of the Static Coronagraphsupporting

confidence: 59%

Section: Impact Of the Static Coronagraphmentioning

confidence: 99%

Section: Robustness To Small Tt Jittermentioning

confidence: 99%

Section: Impact Of the Static Coronagraphmentioning

confidence: 99%

mentioning

confidence: 99%

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Active Correction of Aperture Discontinuities-Optimized Stroke Minimization. II. Optimization for Future Missions

Mazoyer

Pueyo

N’Diaye

et al. 2017

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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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Vortex coronagraphs for the Habitable Exoplanet Imaging Mission concept: theoretical performance and telescope requirements

Ruane

Mawet

Mennesson

et al. 2018

J. Astron. Telesc. Instrum. Syst.

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The Habitable Exoplanet Imaging Mission (HabEx) concept requires an optical coronagraph that provides deep starlight suppression over a broad spectral bandwidth, high throughput for point sources at small angular separation, and insensitivity to temporally-varying, low-order aberrations. Vortex coronagraphs are a promising solution that perform optimally on off-axis, monolithic telescopes and may also be designed for segmented telescopes with minor losses in performance. We describe the key advantages of vortex coronagraphs on off-axis telescopes: 1) Unwanted diffraction due to aberrations is passively rejected in several low-order Zernike modes relaxing the wavefront stability requirements for imaging Earth-like planets from <10 to >100 pm rms. 2) Stars with angular diameters >0.1 λ/D may be sufficiently suppressed.3) The absolute planet throughput is >10%, even for unfavorable telescope architectures. 4) Broadband solutions (∆λ/λ > 0.1) are readily available for both monolithic and segmented apertures. The latter make use of grayscale apodizers in an upstream pupil plane to provide suppression of diffracted light from amplitude discontinuities in the telescope pupil without inducing additional stroke on the deformable mirrors. We set wavefront stability requirements on the telescope, based on a stellar irradiance threshold set at an angular separation of 3 ± 0.5λ/D from the star, and discuss how some requirements may be relaxed by trading robustness to aberrations for planet throughput.

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Polynomial Apodizers for Centrally Obscured Vortex Coronagraphs

Cited by 18 publications

References 52 publications

Active Correction of Aperture Discontinuities-Optimized Stroke Minimization. II. Optimization for Future Missions

Active Correction of Aperture Discontinuities-Optimized Stroke Minimization. II. Optimization for Future Missions

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

Vortex coronagraphs for the Habitable Exoplanet Imaging Mission concept: theoretical performance and telescope requirements

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