On-sky validation of image-based adaptive optics wavefront sensor referencing

Skaf, Nour; Guyon, Olivier; Gendron, É.; Ahn, Kyohoon; Bertrou-Cantou, Arielle; Boccaletti, A.; Cranney, Jesse; Currie, Thayne; Déo, Vincent; Edwards, Billy; Ferreira, Florian; Gratadour, Damien; Lozi, Julien; Norris, Barnaby; Sevin, Arnaud; Vidal, Fabrice; Vievard, Sébastien

doi:10.1051/0004-6361/202141514

Cited by 11 publications

(7 citation statements)

References 21 publications

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“…The "DrWHO" focal plane wavefront sensing algorithm 20 reduces the effects of non-common path aberrations (NCPAs) between the wavefront sensor and VAMPIRES by altering the wavefront sensor reference for convergence of the AO loop. DrWHO has been demonstrated on-sky 21 and coronagraphically in the near-IR. 20 Another technique for improving post-coronagraphic contrast is spatial linear dark field control (LDFC), which uses electric field conjugation to "learn" the NCPAs while on a bright reference star, and then removes NCPAs from our science target using the learned NCPAs.…”

Section: Discussionmentioning

confidence: 97%

A Visible-light Lyot Coronagraph for SCExAO/VAMPIRES

Lucas¹,

Bottom²,

Guyon³

et al. 2022

Preprint

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We describe the design and initial results from a visible-light Lyot coronagraph for SCExAO/VAMPIRES. The coronagraph is comprised of four hard-edged, partially transmissive focal plane masks with inner working angles of 36 mas, 55 mas, 92 mas and 129 mas, respectively. The Lyot stop is a reflective, undersized design with a geometric throughput of 65.7%. Our preliminary on-sky contrast is 10 −2 at 0.1 to 10 −4 at 0.75 for all mask sizes. The coronagraph was deployed in early 2022 and is available for open use.

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Section: Discussionmentioning

confidence: 97%

A Visible-light Lyot Coronagraph for SCExAO/VAMPIRES

Lucas¹,

Bottom²,

Guyon³

et al. 2022

Preprint

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“…9 The test was performed in support of the PSF-sharpening iterative DrWHO algorithm where the AO control loop rewards WFS frames corresponding to sharp PSF realizations. 10,11 Results are shown in Figure 4. Example WFS and PSF frames are shown at the top.…”

Section: Experimental Validation Of Unique Wfs-to-psf Mappingmentioning

confidence: 99%

High contrast imaging at the photon noise limit with WFS-based PSF calibration

Guyon

Norris²,

Martinod³

et al. 2022

Adaptive Optics Systems VIII

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Speckle Noise is the dominant source of error in high contrast imaging with adaptive optics system. We discuss the potential for wavefront sensing telemetry to calibrate speckle noise with sufficient precision and accuracy so that it can be removed in post-processing of science images acquired by high contrast imaging instruments. In such a self-calibrating system, exoplanet detection would be limited by photon noise and be significantly more robust and efficient than in current systems. We show initial laboratory and on-sky tests, demonstrating over short timescale that residual speckle noise is indeed calibrated to an accuracy exceeding readout and photon noise in the high contrast region. We discuss immplications for the design of space and ground high-contrast imaging systems.

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“…Several post-processing methods are available to remove the static speckles, such as angular differential imaging (ADI; Marois et al 2006), reference star differential imaging (RDI; Ruane et al 2019), spectral differential imaging (SDI; Sparks & Ford 2002), and polarimetric differential imaging (PDI; Kuhn et al 2001). Even though these post-processing methods effectively improve the contrast in the science image, they are still limited by the quasi-static and dynamic speckles (Guyon 2004;Martinez et al 2012;Martinache 2013;Skaf et al 2021;Skaf et al 2022). The ideal solution for removing quasi-static and dynamic speckles is focal plane wavefront sensing and control (FPWFS&C).…”

Section: Introductionmentioning

confidence: 99%

Combining EFC with spatial LDFC for high-contrast imaging on Subaru/SCExAO

Ahn¹,

Guyon²,

Lozi³

et al. 2023

A&A

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Context. Exoplanet direct imaging is a key science goal of current ground-based telescopes as well as of future ground-based extremely large telescopes and space-based telescopes. Several high-contrast imaging (HCI) systems for direct exoplanet imaging have been developed and are implemented on current telescopes. Despite recent developments in HCI systems, the contrast they deliver is limited by non-common path aberrations (NCPAs) and residual wavefront errors of the adaptive optics (AO) system. To overcome this limitation and reach higher contrast, HCI systems need focal plane wavefront-sensing and control (FPWFS&C) techniques. Aims. We propose a method that provides both deep contrast and a 100% duty cycle by combining two complementary FPWFS&C methods: electric field conjugation (EFC), and spatial linear dark field control (LDFC). The ultimate goal of this work is to generate the high contrast zone, which is called the dark hole, in the focal plane by using EFC and to maintain the contrast within the highcontrast zone by using spatial LDFC without interrupting science observations. We describe the practical implementation, quantify the linearity range over which LDFC can operate, and derive its photon-noise-limited dynamical performance. Methods. We implemented EFC+LDFC on the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) instrument using its internal light source (off-sky). We first deployed the implicit EFC (iEFC) algorithm to generate the dark hole with a classical Lyot coronagraph (CLC) with a 114 mas diameter focal-plane mask at 1550 nm wavelength. This iEFC algorithm was deployed with pair-wise probes. Using iEFC with pair-wise probes, we directly measured the response matrix of the deformable mirror (DM) modes and built the control matrix by inverting the response matrix. After the calibration process, we generated the dark hole by closing the iEFC loop. When the dark hole was generated, we implemented spatial LDFC to restore and maintain the contrast of the dark hole. In the tests shown here, we introduced static and quasi-static speckles, and then we operated spatial LDFC in closed loop to verify its performance. We used numerical simulations to derive linearity range and photon-noise-limited dynamical performance. Results. Using iEFC, we generated the dark hole with a ∼2×10 −7 contrast in a narrow-band filter (λ = 1550 ± 25 nm). We reached a contrast floor limited by the camera noise. Comparison between pre-and post-iEFC images shows that with iEFC in closed-loop operation, an improvement in contrast of a factor ≈100-500× was reached across the dark hole. In the spatial LDFC experiments, we were able to nearly fully remove the speckles generated by the DM perturbation and maintain the contrast of the dark hole. Conclusions. This work presents the first laboratory demonstration of combining two FPWFS&C methods, iEFC and spatial LDFC. Linear range and photon-noise-limited sensitivity are provided to derive close-loop performance for on-sky systems. Our results provide a promising approach for ...

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On-sky validation of image-based adaptive optics wavefront sensor referencing

Cited by 11 publications

References 21 publications

A Visible-light Lyot Coronagraph for SCExAO/VAMPIRES

A Visible-light Lyot Coronagraph for SCExAO/VAMPIRES

High contrast imaging at the photon noise limit with WFS-based PSF calibration

Combining EFC with spatial LDFC for high-contrast imaging on Subaru/SCExAO

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