Experimental verification of the frozen flow atmospheric turbulence assumption with use of astronomical adaptive optics telemetry

Poyneer, Lisa; Dam, Marcos van; Véran, Jean-Pierre

doi:10.1364/josaa.26.000833

Cited by 97 publications

(54 citation statements)

References 20 publications

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“…Because of its simplicity, the FFH is frequently used as the basis for numerical studies of telescope imaging performance, particularly in the modeling of adaptive optics (AO) systems. While the FFH is observed not to hold in the real world over long time scales, a number of studies have shown that it is a reasonable approximation for short but still interesting periods [5,10,11].…”

Section: Frozen Flow Hypothesismentioning

confidence: 97%

Fast PSF reconstruction using the frozen flow hypothesis

Chu

Knepper

Nagy

et al. 2011

Imaging and Applied Optics

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When imaging space objects from ground-based telescopes, observed images are degraded by atmospheric blurring. If an accurate estimate of the point spread function (PSF) is known, then deconvolution algorithms can be used to restore the image. Wavefront sensors (WFS) collect gradients of the wavefront, which can then be used to estimate the PSF. However, the relatively coarse grid used by a typical WFS limits the accuracy of the PSF estimate, especially when there is severe atmospheric turbulence. Using the frozen flow hypothesis, it is possible to capture the inherent temporal correlations present in wavefronts in consecutive frames of data. Exploiting these correlations can lead to more accurate estimation of the PSF. Here we address the computational aspects of the problem. Specifically we show that the process of extracting additional information from the correlated WFS data can be done by solving a sparse linear least squares problem.

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Section: Frozen Flow Hypothesismentioning

confidence: 97%

Fast PSF reconstruction using the frozen flow hypothesis

Chu

Knepper

Nagy

et al. 2011

Imaging and Applied Optics

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“…For the simulations we usually used datasets of 10 ms, as this is the time scale where one expects TFFH to dominate the turbulence evolution. However, it is also possible to take longer datasets for the wind measurements and only apply the piston reconstruction to shorter times, as the wind is supposed to be stable over longer time scales (Avila et al 2006;Poyneer et al 2009). This is done with a moving average and can further decrease the noise in the cross-correlation, which will be especially important for on-sky data.…”

Section: Wind Vector From Wfs Measurementmentioning

confidence: 99%

P-REx: The Piston Reconstruction Experiment for infrared interferometry

Widmann

Pott

Velasco

2017

Monthly Notices of the Royal Astronomical Society

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For sensitive infrared interferometry, it is crucial to control the differential piston evolution between the used telescopes. This is classically done by the use of a fringe tracker. In this work, we develop a new method to reconstruct the temporal piston variation from the atmosphere, by using real-time data from adaptive optics wavefront sensing: the Piston Reconstruction Experiment (P-REx). In order to understand the principle performance of the system in a realistic multilayer atmosphere it is first extensively tested in simulations. The gained insights are then used to apply P-REx to real data, in order to demonstrate the benefit of using P-REx as an auxiliary system in a real interferometer. All tests show positive results, which encourages further research and eventually a real implementation. Especially the tests on on-sky data showed that the atmosphere is, under decent observing conditions, sufficiently well structured and stable, in order to apply P-REx. It was possible to conveniently reconstruct the piston evolution in two-thirds of the datasets from good observing conditions (r 0 ∼ 30 cm). The main conclusion is that applying the piston reconstruction in a real system would reduce the piston variation from around 10 µm down to 1 to 2 µm over timescales of up to two seconds. This suggests an application for mid-infrared interferometry, for example for MATISSE at the VLTI or the LBTI. P-REx therefore provides the possibility to improve interferometric measurements without the need for more complex AO systems than already in regular use at 8m-class telescopes.

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“…In our recent work, with colleagues, we used telemetry from the Keck and Altair AO systems to experimentally validate the frozen flow hypothesis and clearly detect multiple layers of translating turbulence [20]. Here we use some of that data obtained with…”

Section: A Experimental Observation Of Frozen Flow Aliasesmentioning

confidence: 99%

Kalman filtering to suppress spurious signals in adaptive optics control

Poyneer

Véran

2010

J. Opt. Soc. Am. A

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1In many scenarios, an Adaptive Optics (AO) control system operates in the presence of temporally non-white noise. We use a Kalman filter with a state space formulation that allows suppression of this colored noise, hence improving residual error over the case where the noise is assumed to be white. We demonstrate the effectiveness of this new filter in the case of the estimated Gemini Planet Imager tip-tilt environment, where there are both common-path and non-common path vibrations. We discuss how this same framework can also be used to suppress spatial aliasing during predictive wavefront control assuming frozen flow in a low-order AO system without a spatially filtered wavefront sensor, and present experimental measurements from Altair that clearly reveal these aliased components.

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Experimental verification of the frozen flow atmospheric turbulence assumption with use of astronomical adaptive optics telemetry

Cited by 97 publications

References 20 publications

Fast PSF reconstruction using the frozen flow hypothesis

Fast PSF reconstruction using the frozen flow hypothesis

P-REx: The Piston Reconstruction Experiment for infrared interferometry

Kalman filtering to suppress spurious signals in adaptive optics control

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