Predicting contrast sensitivity to segmented aperture misalignment modes for the HiCAT testbed

Laginja, Iva; Soummer, Rémi; Mugnier, Laurent M.; Pueyo, Laurent; Sauvage, Jean-François; Leboulleux, Lucie; Coyle, Laura; Knight, J. Scott; Perrin, Marshall D.; Will, Scott D.; Noss, James; Brooks, Keira; Fowler, J.

doi:10.1117/12.2560113

Cited by 5 publications

(2 citation statements)

References 44 publications

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“…Overall, the number of segments in the pupil will raise competing effects that will influence the overall tolerances and will be highly influenced by the type of coronagraph. 74 In Sec. 5.1, we briefly mentioned the observed trade-off between coronagraph throughput, FPM size, and per-segment requirements.…”

Section: Discussionmentioning

confidence: 99%

Analytical tolerancing of segmented telescope co-phasing for exo-Earth high-contrast imaging

Laginja

Soummer

Mugnier

et al. 2021

J. Astron. Telesc. Instrum. Syst.

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This paper introduces an analytical method to calculate segment-level wavefront error (WFE) tolerances to enable the detection of faint extra-solar planets using segmentedaperture telescopes in space. This study provides a full treatment of the case of spatially uncorrelated segment phasing errors for segmented telescope coronagraphy, which has so far only been approached using ad-hoc Monte Carlo (MC) simulations. Instead of describing the wavefront tolerance globally for all segments, our method produces spatially dependent requirement maps. We relate the statistical mean contrast in the coronagraph dark hole to the standard deviation of the WFE of each individual segment on the primary mirror. This statistical framework for segment-level tolerancing extends the Pair-based Analytical model for Segmented Telescope Imaging from Space (PASTIS), which is based uniquely on a matrix multiplication for the optical propagation. We confirm our analytical results with MC simulations of end-to-end optical propagations through a coronagraph. Comparing our results for the Apodized Pupil Lyot Coronagraph designs for the Large Ultraviolet Optical Infrared telescope to previous studies, we show general agreement but we provide a relaxation of the requirements for a significant subset of segments in the pupil. These requirement maps are unique to any given telescope geometry and coronagraph design. The spatially uncorrelated segment tolerances we calculate are a key element of a complete error budget that will also need to include allocations for correlated segment contributions. We discuss how the PASTIS formalism can be extended to the spatially correlated case by deriving the statistical mean contrast and its variance for a nondiagonal aberration covariance matrix. The PASTIS tolerancing framework therefore brings a new capability that is necessary for the global tolerancing of future segmented space observatories.

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Section: Discussionmentioning

confidence: 99%

Analytical tolerancing of segmented telescope co-phasing for exo-Earth high-contrast imaging

Laginja

Soummer

Mugnier

et al. 2021

J. Astron. Telesc. Instrum. Syst.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Overall, the number of segments in the pupil will raise competing effects that will influence the overall tolerances, and will be highly influenced by the type of coronagraph. 74 In Sec. 5.1, we briefly mentioned the observed trade-off between coronagraph throughput, FPM size and persegment requirements.…”

Section: Discussionmentioning

confidence: 99%

Analytical tolerancing of segmented telescope co-phasing for exo-Earth high-contrast imaging

Laginja,

Soummer,

Mugnier

et al. 2021

Preprint

Self Cite

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This paper introduces an analytical method to calculate segment-level wavefront error tolerances in order to enable the detection of faint extra-solar planets using segmented-aperture telescopes in space. This study provides a full treatment of the case of spatially uncorrelated segment phasing errors for segmented telescope coronagraphy, which has so far only been approached using ad hoc Monte-Carlo simulations. Instead of describing the wavefront tolerance globally for all segments, our method produces spatially dependent requirement maps. We relate the statistical mean contrast in the coronagraph dark hole to the standard deviation of the wavefront error of each individual segment on the primary mirror. This statistical framework for segment-level tolerancing extends the Pair-based Analytical model for Segmented Telescope Imaging from Space (PASTIS), which is based uniquely on a matrix multiplication for the optical propagation. We confirm our analytical results with Monte-Carlo simulations of end-to-end optical propagations through a coronagraph. Comparing our results for the Apodized Pupil Lyot Coronagraph designs for the Large UltraViolet Optical InfraRed (LUVOIR) telescope to previous studies, we show general agreement but we provide a relaxation of the requirements for a significant subset of segments in the pupil. These requirement maps are unique to any given telescope geometry and coronagraph design. The spatially uncorrelated segment tolerances we calculate are a key element of a complete error budget that will also need to include allocations for correlated segment contributions. We discuss how the PASTIS formalism can be extended to the spatially correlated case by deriving the statistical mean contrast and its variance for a non-diagonal aberration covariance matrix. The PASTIS tolerancing framework therefore brings a new capability that is necessary for the global tolerancing of future segmented space observatories.

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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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Predicting contrast sensitivity to segmented aperture misalignment modes for the HiCAT testbed

Cited by 5 publications

References 44 publications

Analytical tolerancing of segmented telescope co-phasing for exo-Earth high-contrast imaging

Analytical tolerancing of segmented telescope co-phasing for exo-Earth high-contrast imaging

Analytical tolerancing of segmented telescope co-phasing for exo-Earth high-contrast imaging

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

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