The compute and control for adaptive optics (CACAO) real-time control software package

Guyon, Olivier; Sevin, Arnaud; Gratadour, Damien; Bernard, Julien; Ltaief, Hatem; Sukkari, Dalal; Cetre, Sylvain; Skaf, Nour; Lozi, Julien; Martinache, Frantz; Clergeon, Christophe; Norris, Barnaby; Wong, Alison; Males, Jared R.

doi:10.1117/12.2314315

Cited by 38 publications

(40 citation statements)

References 10 publications

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“…11 The RTC hardware is based on an x86 architecture linux server with a Geforce GTX 1080 ti Graphical Processing Unit; its software is based on the Compute and Control for Adaptive optics (CACAO) realtime control software package. 10 To minimize impact on the existing AO system, the PYWFS RTC interfaces with the existing Keck MGAOS RTC rather than the DM and tip/tilt hardware directly. Section 3 describes our implementation of EOF pWFC in the PYWFS RTC.…”

Section: The Keck Planet Imager and Characterizermentioning

confidence: 99%

“…For example, Poyneer et al 2007, 5 2008 6 describe Fourier-based wind predictive control by identifying the windspeeds at different layers in the atmosphere using real-time AO telemetry data; Sivo et al 2016 7 discuss the real-time implementation of a Linear-quadratic-Gaussian (LQG) tip-tilt controller for Gemini/GeMS; Correia et al 2017 8 present a distributed Kalman filter to reduce anisoservo-lag and aliasing errors while simultaneously minimizing the total residual wavefront variance. Recently, Guyon & Males (2017)9 presented Empirical Orthogonal Functions, a method of linear control that is now in regular use at SCExAO 10. …”

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confidence: 99%

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Demonstrating predictive wavefront control with the Keck II near-infrared pyramid wavefront sensor

Jensen-Clem

Bond

Cetre

et al. 2019

Techniques and Instrumentation for Detection of Exoplanets IX

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The success of ground-based instruments for high contrast exoplanet imaging depends on the degree to which adaptive optics (AO) systems can mitigate atmospheric turbulence. While modern AO systems typically suffer from millisecond time lags between wavefront measurement and control, predictive wavefront control (pWFC) is a means of compensating for those time lags using previous wavefront measurements, thereby improving the raw contrast in the post-coronagraphic science focal plane. A method of predictive control based on Empirical Orthogonal Functions (EOF) has previously been proposed and demonstrated on Subaru/SCExAO. In this paper we present initial tests of this method for application to the near-infrared pyramid wavefront sensor (PYWFS) recently installed in the Keck II AO system. We demonstrate the expected root-mean-square (RMS) wavefront error and contrast benefits of pWFC based on simulations, applying pWFC to on-sky telemetry data saved during commissioning of the PYWFS. We discuss how the performance varies as different temporal and spatial scales are included in the computation of the predictive filter. We further describe the implementation of EOF pWFC within the PYWFS dedicated real-time controller (RTC), and, via daytime testing at the observatory, we demonstrate the performance of pWFC in real time when pre-computed phase screens are applied to the deformable mirror (DM).

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Section: The Keck Planet Imager and Characterizermentioning

confidence: 99%

mentioning

confidence: 99%

Demonstrating predictive wavefront control with the Keck II near-infrared pyramid wavefront sensor

Jensen-Clem

Bond

Cetre

et al. 2019

Techniques and Instrumentation for Detection of Exoplanets IX

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“…These artifacts first come from the wavefront errors due to the atmospheric turbulence residuals after ExAO correction. Different upgrades are under investigation to push the limits of the AO performance further, such as new or additional deformable mirrors, high-sensitivity wavefront sensors, control loops with frequency faster than 1 kHz, and predictive control algorithms (e.g., Fusco et al 2016;Chilcote et al 2018;Guyon et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Calibration of quasi-static aberrations in exoplanet direct-imaging instruments with a Zernike phase-mask sensor

Vigan

N’Diaye

Dohlen

et al. 2019

A&A

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Second-generation exoplanet imagers using extreme adaptive optics (ExAO) and coronagraphy have demonstrated their great potential for studying close circumstellar environments and for detecting new companions and helping to understand their physical properties. However, at very small angular separation, their performance in contrast is limited by several factors: diffraction by the complex telescope pupil (central obscuration and spiders) not perfectly canceled by the coronagraph, residual dynamic wavefront errors, chromatic wavefront errors, and wavefront errors resulting from noncommon path aberrations (NCPAs). These latter are differential aberrations between the visible wavefront sensing path of the ExAO system and the near-infrared science path in which the coronagraph is located. In a previous work, we demonstrated the use of a Zernike wavefront sensor called ZELDA for sensing NCPAs in the VLT/SPHERE exoplanet imager and their compensation with the high-order deformable mirror of the instrument. These early tests on the internal light source led to encouraging results for the attenuation of the quasi-static speckles at very small separation. In the present work, we move to the next step with the on-sky validation of NCPA compensation with ZELDA. With an improved procedure for the compensation of NCPAs, we start by reproducing previous results on the internal source. We show that the amount of aberration integrated between 1 and 15 cycles/pupil (c/p) is decreased by a factor of approximately five, which translates into a gain in raw contrast of between 2 and 3 at separations below 300 mas. On sky, we demonstrate that NCPA compensation works in closed loop, leading to an attenuation of the amount of aberration by a factor of approximately two. However, we identify a loss of sensitivity for the sensor that is only partly explained by the difference in Strehl ratio between the internal and on-sky measurements. Our simulations show that the impact of ExAO residuals on ZELDA measurements is negligible for integration times beyond a few tenths of a second. Coronagraphic imaging on sky is improved in raw contrast by a factor of 2.5 at most in the ExAO-corrected region. We use coronagraphic image reconstruction based on a detailed model of the instrument to demonstrate that both internal and on-sky raw contrasts can be precisely explained, and we establish that the observed performance after NCPA compensation is no longer limited by an improper compensation for aberration but by the current apodized-pupil Lyot coronagraph design. We finally conclude that a coronagraph upgrade combined to a proper NCPA compensation scheme could easily bring a gain in raw contrast of a factor of two to three below 200 mas.

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“…The Compute And Control for Adaptive Optics (CACAO) 17 is an open source software package written in C, optimized for performance using multi-core CPUs and GPUs for high computing throughput. The main functionalities of this solution are:…”

Section: Cacao Solutionmentioning

confidence: 99%

A near-infrared pyramid wavefront sensor for Keck adaptive optics: real-time controller

Cetre

Guyon

Bond

et al. 2018

Adaptive Optics Systems VI

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A new real-time control system will be implemented within the Keck II adaptive optics system to support the new near-infrared pyramid wavefront sensor. The new real-time computer has to interface with an existing, very productive adaptive optics system. We discuss our solution to install it in an operational environment without impacting science. This solution is based on an independent SCExAO-based pyramid wavefront sensor realtime processor solution using the hardware interfaces provided by the existing Keck II real-time controller. We introduce the new pyramid real-time controller system design, its expected performance, and the modification of the operational real-time controller to support the pyramid system including interfacing with the existing deformable and tip-tilt mirrors. We describe the integration of the Saphira detector-based camera and the Boston Micromachines kilo-DM in this new architecture. We explain the software architecture and philosophy, the shared memory concept and how the real-time computer uses the power of GPUs for adaptive optics control. We discuss the strengths and weaknesses of this architecture and how it can benefit other projects. The motion control of the devices deployed on the Keck II adaptive optics bench to support the alignment of the light on the sensors is also described. The interfaces, developed to deal with the rest of the Keck telescope systems in the observatory distributed system, are reviewed. Based on this experience, we present which design ideas could have helped us integrate the new system with the previous one and the resultant performance gains.

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The compute and control for adaptive optics (CACAO) real-time control software package

Cited by 38 publications

References 10 publications

Demonstrating predictive wavefront control with the Keck II near-infrared pyramid wavefront sensor

Demonstrating predictive wavefront control with the Keck II near-infrared pyramid wavefront sensor

Calibration of quasi-static aberrations in exoplanet direct-imaging instruments with a Zernike phase-mask sensor

A near-infrared pyramid wavefront sensor for Keck adaptive optics: real-time controller

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