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Pyramid wavefront sensors (PWFSs) are the preferred choice for current and future extreme adaptive optics (XAO) systems. Almost all instruments use the PWFS in its modulated form to mitigate its limited linearity range. However, this…

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…

Instrumentation and Methods for Astrophysics · Physics 2019-09-13 Rebecca Jensen-Clem , Charlotte Z. Bond , Sylvain Cetre , Eden McEwen , Peter Wizinowich , Sam Ragland , Dimitri Mawet , James Graham

With its high sensitivity, the Pyramid wavefront sensor (PyWFS) is becoming an advantageous sensor for astronomical adaptive optics (AO) systems. However, this sensor exhibits significant non-linear behaviours leading to challenging AO…

Instrumentation and Methods for Astrophysics · Physics 2021-05-12 Vincent Chambouleyron , Olivier Fauvarque , Jean-François Sauvage , Benoît Neichel , Thierry Fusco

Super-resolution (SR) refers to a combination of optical design and signal processing techniques jointly employed to obtain reconstructed wave-fronts at a higher-resolution from multiple low-resolution samples, overcoming the intrinsic…

Instrumentation and Methods for Astrophysics · Physics 2025-12-22 Carlos M. Correia , Charlotte Z. Bond , João Aveiro , François Leroux , Cédric Taïssir Heritier , Christophe Vérinaud

The pyramid wavefront sensor (PyWFS) has become increasingly popular to use in adaptive optics (AO) systems due to its high sensitivity. The main drawback of the PyWFS is that it is inherently nonlinear, which means that classic linear…

Instrumentation and Methods for Astrophysics · Physics 2023-11-07 Alison P. Wong , Barnaby R. M. Norris , Vincent Deo , Peter G. Tuthill , Richard Scalzo , David Sweeney , Kyohoon Ahn , Julien Lozi , Sebastien Vievard , Olivier Guyon

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…

Instrumentation and Methods for Astrophysics · Physics 2019-05-01 Victoria Hutterer , Ronny Ramlau , Iuliia Shatokhina

The pyramid wavefront sensor (P-WFS) has replaced the Shack-Hartmann (SH-) WFS as sensor of choice for high performance adaptive optics (AO) systems in astronomy because of its flexibility in pupil sampling, its dynamic range, and its…

For natural guide start adaptive optics (AO) systems, pyramid wavefront sensors (PWFSs) can provide significant increase in sensitivity over the traditional Shack-Hartmann, but at the cost of a reduced linear range. When using a linear…

Instrumentation and Methods for Astrophysics · Physics 2023-12-05 Finn Archinuk , Rehan Hafeez , Sébastien Fabbro , Hossen Teimoorinia , Jean-Pierre Véran

Current and future high-contrast imaging instruments require extreme Adaptive Optics (XAO) systems to reach contrasts necessary to directly image exoplanets. Telescope vibrations and the temporal error induced by the latency of the control…

Instrumentation and Methods for Astrophysics · Physics 2020-12-04 Rico Landman , Sebastiaan Y. Haffert , Vikram M. Radhakrishnan , Christoph U. Keller

Wavefront sensors encode phase information of an incoming wavefront into an intensity pattern that can be measured on a camera. Several kinds of wavefront sensors (WFS) are used in astronomical adaptive optics. Amongst them, Fourier-based…

Optical aberrations prevent telescopes from reaching their theoretical diffraction limit. Once estimated, these aberrations can be compensated for using deformable mirrors in a closed loop. Focal plane wavefront sensing enables the…

The sensitivity of the the pyramid wavefront sensor (PyWFS) has made it a popular choice for astronomical adaptive optics (AAO) systems, and it is at its most sensitive when it is used without modulation of the input beam. In non-modulated…

Instrumentation and Methods for Astrophysics · Physics 2018-05-09 Richard A. Frazin

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…

Instrumentation and Methods for Astrophysics · Physics 2020-06-17 Carlos M. Correia , Olivier Fauvarque , Charlotte Z. Bond , Vincent Chambouleyron , Jean-Francois Sauvage , Thierry Fusco

We propose a novel adaptive reinforcement learning control approach for fault tolerant control of degrading systems that is not preceded by a fault detection and diagnosis step. Therefore, \textit{a priori} knowledge of faults that may…

Systems and Control · Electrical Eng. & Systems 2020-08-12 Ibrahim Ahmed , Marcos Quiñones-Grueiro , Gautam Biswas

In this paper, we address the inverse problem of fast, stable, and high-quality wavefront reconstruction from pyramid wavefront sensor data for Adaptive Optics systems on Extremely Large Telescopes. For solving the indicated problem we…

Instrumentation and Methods for Astrophysics · Physics 2019-05-01 Victoria Hutterer , Ronny Ramlau , Iuliia Shatokhina

We propose a new type of Wave Front Sensor (WFS) derived from the Pyramid WFS (PWFS). This new WFS, called the Flattened Pyramid-WFS (FPWFS), has a reduced Pyramid angle in order to optically overlap the four pupil images into an unique…

Instrumentation and Methods for Astrophysics · Physics 2015-08-06 O. Fauvarque , B. Neichel , T. Fusco , J. F. Sauvage

Current and future high-contrast imaging instruments require extreme adaptive optics (XAO) systems to reach contrasts necessary to directly image exoplanets. Telescope vibrations and the temporal error induced by the latency of the control…

Instrumentation and Methods for Astrophysics · Physics 2021-08-26 Rico Landman , Sebastiaan Y. Haffert , Vikram M. Radhakrishnan , Christoph U. Keller

Most adaptive optics (AO) systems using pyramid wavefront sensors (PyWFS) to estimate the phase of the pupil field use mechanical modulation of the beam in order to increase the dynamic range in low-order modes so the PyWFS can usefully…

Instrumentation and Methods for Astrophysics · Physics 2017-08-31 Richard Frazin

Context. The diffusion of adaptive optics systems in astronomical instrumentation for large ground-based telescopes is rapidly increasing and the pyramid wavefront sensor is replacing the Shack-Hartmann as the standard solution for single…

Instrumentation and Methods for Astrophysics · Physics 2023-09-27 Guido Agapito , Enrico Pinna , Simone Esposito , Cedric Taïssir Heritier , Sylvain Oberti

Many autonomous systems face safety challenges, requiring robust closed-loop control to handle physical limitations and safety constraints. Real-world systems, like autonomous ships, encounter nonlinear dynamics and environmental…

Robotics · Computer Science 2024-04-03 Aksel Vaaler , Svein Jostein Husa , Daniel Menges , Thomas Nakken Larsen , Adil Rasheed
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