Experimental study of an optimised Pyramid wave-front sensor for Extremely Large Telescopes

Bond, C.; Hadi, Kacem El; Sauvage, Jean-François; Correia, Carlos; Fauvarque, Olivier; Rabaud, Didier; Lamb, Masen; Neichel, Benoît; Fusco, Thierry

doi:10.1117/12.2232968

Cited by 7 publications

(6 citation statements)

References 2 publications

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“…Since the PWFS was introduced by Ragazzoni in the 1990s, 10 it has gradually gained more and more attention from the scientific community. Multiple theoretical studies, numerical simulations, 13,[15][16][17][18][19] and laboratory investigations in optical test benches [20][21][22][23][24][25] have demonstrated numerous advantages of the PWFS over the standard Shack-Hartmann wavefront sensor (SH-WFS). Among those are the ability to achieve an enhanced and adjustable sensitivity, improved signal-to-noise ratio (reduced noise propagation), an improved robustness to spatial aliasing, and an adjustable pupil sampling.…”

Section: Pyramid Sensor Features Applications and Modern Challengesmentioning

confidence: 99%

Review on methods for wavefront reconstruction from pyramid wavefront sensor data

Shatokhina

Hutterer

Ramlau

2020

J. Astron. Telesc. Instrum. Syst.

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Pyramid wavefront sensors are planned to be a part of many instruments that are currently under development for the extremely large telescopes (ELT). The unprecedented scales of the upcoming ELT-era instruments are inevitably connected with serious challenges for wavefront reconstruction and control algorithms. Apart from the huge number of correcting elements to be controlled in real-time, real-life features such as the segmentation of the telescope pupil, the low wind effect, the nonlinearity of the pyramid sensor, and the noncommon path aberrations will have a significantly larger impact on the imaging quality in the ELT framework than they ever had before. We summarize various kinds of wavefront reconstruction algorithms for the pyramid wavefront sensor. Based on several forward models, different algorithms were developed in the last decades for linear and nonlinear wavefront correction. The core ideas of the algorithms are presented, and a detailed comparison of the presented methods with respect to underlying pyramid sensor models, computational complexities, and reconstruction qualities is given. In addition, we review the existing and possible solutions for the above-named real-life phenomena. At the same time, directions for further investigations are sketched.

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Section: Pyramid Sensor Features Applications and Modern Challengesmentioning

confidence: 99%

Review on methods for wavefront reconstruction from pyramid wavefront sensor data

Shatokhina

Hutterer

Ramlau

2020

J. Astron. Telesc. Instrum. Syst.

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“…∫ Ω i q dΩ with Ω the domain set by the valid pixels (Vérinaud (2004)). The latter is considered a more robust option (Bond et al (2016)).…”

Section: Impulse Response Of a Pwfsmentioning

confidence: 99%

Performance limits of adaptive-optics/high-contrast imagers with pyramid wave-front sensors

Correia,

Fauvarque,

Bond

et al. 2020

Preprint

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Advanced AO systems will likely utilise Pyramid wave-front sensors (PWFS) over the traditional Shack-Hartmann sensor in the quest for increased sensitivity, peak performance and ultimate contrast. Here, we wish to bring knowledge and quantify the PWFS theoretical limits as a means to highlight its properties and use cases. We explore forward models for the PWFS in the spatial-frequency domain for they prove quite useful since a) they emanate directly from physical-optics (Fourier) diffraction theory; b) provide a straightforward path to meaningful error breakdowns, c) allow for reconstruction algorithms with O(n log(n)) complexity for large-scale systems and d) tie in seamlessly with decoupled (distributed) optimal predictive dynamic control for performance and contrast optimisation. All these aspects are dealt with here. We focus on recent analytical PWFS developments and demonstrate the performance using both analytic and end-to-end simulations. We anchor our estimates with observed on-sky contrast on existing systems and then show very good agreement between analytical and Monte-Carlo estimates for the PWFS. For a potential upgrade of existing high-contrast imagers on 10 m-class telescopes with visible or near-infrared PWFS, we show under median conditions at Paranal a contrast improvement (limited by chromatic and scintillation effects) of 2x-5x by replacing the wave-front sensor alone at large separations close to the AO control radius where aliasing dominates, and factors in excess of 10x by coupling distributed control with the PWFS over most of the AO control region, from small separations starting with the Inner Working Angle of typically 1-2 λ/D to the AO correction edge (here 20 λ/D).

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“…It is gradually gaining more and more attention from the scientific community, especially in astronomical AO, due to its increased sensitivity, improved signal-to-noise ratio, robustness to spatial aliasing and adjustable spatial sampling compared to the other popular wavefront sensor choice -the Shack-Hartmann (SH) sensor. Several theoretical studies [8,21,22,48,61,62,70,80,82,81,85] including numerical simulations and laboratory investigations with optical test benches [4,33,52,59,78,84] have Figure 1: Principle of wavefront correction [2]. A deformable mirror reflects a perturbed wavefront and propagates the corrected, planar wavefront to the science camera yielding improved image quality.…”

Section: Introductionmentioning

confidence: 99%

Real-time adaptive optics with pyramid wavefront sensors: part I. A theoretical analysis of the pyramid sensor model

2019

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We consider the mathematical background of the wavefront sensor type that is widely used in Adaptive Optics systems for astronomy, microscopy, and ophthalmology. The theoretical analysis of the pyramid sensor forward operators presented in this paper is aimed at a subsequent development of fast and stable algorithms for wavefront reconstruction from data of this sensor type. In our analysis we allow the sensor to be utilized in both the modulated and non-modulated fashion. We derive detailed mathematical models for the pyramid sensor and the physically simpler roof wavefront sensor as well as their various approximations. Additionally, we calculate adjoint operators which build preliminaries for the application of several iterative mathematical approaches for solving inverse problems such as gradient based algorithms, Landweber iteration or Kaczmarz methods.

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Experimental study of an optimised Pyramid wave-front sensor for Extremely Large Telescopes

Cited by 7 publications

References 2 publications

Review on methods for wavefront reconstruction from pyramid wavefront sensor data

Review on methods for wavefront reconstruction from pyramid wavefront sensor data

Performance limits of adaptive-optics/high-contrast imagers with pyramid wave-front sensors

Real-time adaptive optics with pyramid wavefront sensors: part I. A theoretical analysis of the pyramid sensor model

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