On-sky demonstration of matched filters for wavefront measurements using ELT-scale elongated laser guide stars

Basden, Alastair; Bardou, Lisa; Calia, Domenico Bonaccini; Buey, Tristan; Centrone, Mauro; Chemla, Fanny; Gach, Jean-Luc; Gendron, É.; Gratadour, Damien; Guidolin, I.; Jenkins, David R.; Marchetti, Enrico; Morris, Tim; Myers, R; Osborn, James; Reeves, Andrew; Reyes, M.; Rousset, G.; Lombardi, G.; Townson, Matthew J.; Vidal, Fabrice

doi:10.1093/mnras/stx062

Cited by 10 publications

(9 citation statements)

References 24 publications

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“…9 shows on-sky results obtained using the matched filter algorithm. Further results and details are given by Basden et al 14 .…”

Section: Matched Filteringmentioning

confidence: 90%

On-sky testing of algorithms for extended LGS spots

Basden¹

2017

Proceedings of the Adaptive Optics for Extremely Large Telescopes 5

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We present results of on-sky testing of different algorithms for highly extended LGS spots. We have used the CANARY wide-field AO demonstrator instrument on the 4.2m William Herschel Telescope on La Palma with the ESO Wendelstein LGS unit, launched 40m off-axis to simulate edge sub-apertures of the E-ELT. We investigate the performance of correlation and matched filter algorithms, comparing performance with a traditional centre of gravity. We also present on-sky tests of advanced pixel handling algorithms which we show improve AO system performance, including adaptive windowing (spot tracking), total variation minimisation and brightest pixel selection. Techniques to improve detection of truncated spots are also presented. Additionally, we present a critical study of Shack-Hartmann sensor accuracy with accurate detector readout models, highly applicable to AO system designers when specifying detector performance, or for predicting AO system performance with a given detector.

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“…9 shows on-sky results obtained using the matched filter algorithm. Further results and details are given by Basden et al 14 .…”

Section: Matched Filteringmentioning

confidence: 90%

On-sky testing of algorithms for extended LGS spots

Basden¹

2017

Proceedings of the Adaptive Optics for Extremely Large Telescopes 5

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“…The technique performs less well for sub-apertures observing highly elongated LGS. Previous studies have shown cross-correlation and matched-filter to offer better centroid accuracy than simply centroiding the LGS plume (Basden et al 2014(Basden et al , 2017. This is due to the signal being restricted to one dimension, along the direction of elongation.…”

Section: Discussionmentioning

confidence: 99%

Generating artificial reference images for open loop correlation wavefront sensors

Townson

Love

Saunter

2018

Monthly Notices of the Royal Astronomical Society

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Shack-Hartmann wavefront sensors for both solar and laser guide star adaptive optics (with elongated spots) need to observe extended objects. Correlation techniques have been successfully employed to measure the wavefront gradient in solar adaptive optics systems and have been proposed for laser guide star systems. In this paper we describe a method for synthesising reference images for correlation Shack-Hartmann wavefront sensors with a larger field of view than individual sub-apertures. We then show how these supersized reference images can increase the performance of correlation wavefront sensors in regimes where large relative shifts are induced between sub-apertures, such as those observed in open-loop wavefront sensors. The technique we describe requires no external knowledge outside of the wavefront-sensor images, making it available as an entirely "software" upgrade to an existing adaptive optics system. For solar adaptive optics we show the supersized reference images extend the magnitude of shifts which can be accurately measured from 12% to 50% of the field of view of a sub-aperture and in laser guide star wavefront sensors the magnitude of centroids that can be accurately measured is increased from 12% to 25% of the total field of view of the sub-aperture.

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“…European Solar Telescope [4]). Additionally, existing instruments have also been modelled to demonstrate that proposed novel techniques can improve the AO system performance [5,6]. DASP enables AO system designers to explore the large parameter spaces associated with AO system development, allowing system design trade-offs to be made in an informed manner, with typical parameters including AO system order, number of guide stars, and wavefront sensor pixel scale.…”

Section: Scientific Contribution Of Daspmentioning

confidence: 99%

“…Fig. 4 shows the simulation configuration that is used with the CANARY AO instrument [23], and is an illustrative example of how DASP can be used in real-world situations to significantly reduce on-sky commissioning time [6]. In this case, DASP is used to model the atmosphere, telescope, and AO system optics, providing input to the CANARY real-time control system, and updating the model in response to real-time control system outputs.…”

Section: Hardware-in-the-loop Examplementioning

confidence: 99%

The Durham Adaptive Optics Simulation Platform (DASP): Current status

et al. 2018

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The Durham Adaptive Optics Simulation Platform (DASP) is a Monte-Carlo modelling tool used for the simulation of astronomical and solar adaptive optics systems. In recent years, this tool has been used to predict the expected performance of the forthcoming extremely large telescope adaptive optics systems, and has seen the addition of several modules with new features, including Fresnel optics propagation and extended object wavefront sensing. Here, we provide an overview of the features of DASP and the situations in which it can be used. Additionally, the user tools for configuration and control are described.The Durham adaptive optics (AO) simulation platform (DASP) has been under development since the early 1990s. Its current framework was established in 2006 to meet the challenges of modelling the forthcoming extremely large telescopes, with primary mirror diameters of over 20 m. Since 2006, DASP has been regularly developed to improve computational performance, increase simulation fidelity, and expand the number of features that can be modelled. It uses a modular design, allowing new developments and algorithms to be added whilst maintaining compatibility. DASP is developed primarily in Python and C, and uses pthreads and MPI for parallelization enabling modelling of the largest proposed telescopes on reasonable timescales.

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On-sky demonstration of matched filters for wavefront measurements using ELT-scale elongated laser guide stars

Cited by 10 publications

References 24 publications

On-sky testing of algorithms for extended LGS spots

On-sky testing of algorithms for extended LGS spots

Generating artificial reference images for open loop correlation wavefront sensors

The Durham Adaptive Optics Simulation Platform (DASP): Current status

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