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Extreme wavefront correction is required for coronagraphs on future space telescopes to reach 1e-8 or better starlight suppression for the direct imaging and characterization of exoplanets in reflected light. Thus, a suite of wavefront…

Conventional methods of wavefront reconstruction from the raw data of the Shack-Hartmann sensor use the focal spot shifts and discard the high-frequency information about the wavefront. Phase-retrieval-based methods treat the Hartmann…

This paper aims at presenting a new approach to the electro-sensing problem using wavelets. It provides an efficient algorithm for recognizing the shape of a target from micro-electrical impedance measurements. Stability and resolution…

Numerical Analysis · Mathematics 2013-10-11 Habib Ammari , Stéphane Mallat , Irène Waldspurger , Han Wang

As we look to the next generation of adaptive optics systems, now is the time to develop and explore the technologies that will allow us to image rocky Earth-like planets; wavefront control algorithms are not only a crucial component of…

Earth and Planetary Astrophysics · Physics 2023-09-06 J. Fowler , Rico Landman

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…

Laser guide stars (LGS) are used in many adaptive optics systems to extend sky coverage. The most common wavefront sensor used in combination with a LGS is a Shack-Hartmann wavefront sensor (SHWFS). The Shack-Hartmann has a major…

Instrumentation and Methods for Astrophysics · Physics 2020-12-07 Sebastiaan Y. Haffert , Christoph U. Keller , Richard Dekany

Astronomical adaptive optics systems with open-loop deformable mirror control have recently come on-line. In these systems, the deformable mirror surface is not included in the wavefront sensor paths, and so changes made to the deformable…

Instrumentation and Methods for Astrophysics · Physics 2015-05-30 Alastair Basden , Richard Myers , Eric Gendron

Wavefront shaping is a technique for directing light through turbid media. The theoretical aspects of wavefront shaping are well understood, and under near-ideal experimental conditions, accurate predictions for the expected signal…

Optics · Physics 2024-07-01 Bahareh Mastiani , Daniël W. S. Cox , Ivo M. Vellekoop

An adaptive optics system with a single deformable mirror is being implemented on the THEMIS 90cm solar telescope. This system is designed to operate in the visible and is required to be as robust as possible in order to deliver the best…

Instrumentation and Methods for Astrophysics · Physics 2021-01-11 Michel Tallon , Éric Thiébaut , Maud Langlois , Bernard Gelly , Richard Douet , Clémentine Béchet , Loïc Denis , Gil Moretto

This paper deals with the theoretical principle and optical design of a phase-shifting telescope-interferometer. What is called a "Telescope-Interferometer" (T-I) is indeed a novel, recently proposed Wavefront Error (WFE) sensing technique,…

Optics · Physics 2011-05-19 Francois Henault

Forward-looking sonar can capture high resolution images of underwater scenes, but their interpretation is complex. Generic object detection in such images has not been solved, specially in cases of small and unknown objects. In comparison,…

Computer Vision and Pattern Recognition · Computer Science 2017-09-11 Matias Valdenegro-Toro

To reach the full potential of the new generation of ground based telescopes, an extremely fine adjustment of the phase is required. Wavefront control and correction before detection has therefore become one of the cornerstones of…

Instrumentation and Methods for Astrophysics · Physics 2022-10-25 Vincent Chambouleyron , Olivier Fauvarque , Cédric Plantet , Jean-François Sauvage , Nicolas Levraud , Mahawa Cissé , Benoît Neichel , Thierry Fusco

Future radar systems are expected to use waveforms of a high bandwidth, where the main advantage is an improved range resolution. In this paper, a technique to design robust wideband waveforms for a Multiple-Input-Single-Output system is…

Applications · Statistics 2016-11-17 Ashkan Panahi , Marie Ström , Mats Viberg

Object detection, one of the most fundamental and challenging problems in computer vision, seeks to locate object instances from a large number of predefined categories in natural images. Deep learning techniques have emerged as a powerful…

Computer Vision and Pattern Recognition · Computer Science 2019-08-23 Li Liu , Wanli Ouyang , Xiaogang Wang , Paul Fieguth , Jie Chen , Xinwang Liu , Matti Pietikäinen

The ingot wavefront sensor (I-WFS) has been proposed, for ELT-like apertures, as a possible pupil plane WFS, to cope with the geometrical characteristics of a laser guide star (LGS). Within the study and development of such a WFS, on-going…

An extremely simple single-trace transmission example shows how an extended source formulation of full waveform inversion can produce an optimization problem without spurious local minima ("cycle skipping"). The data consist of a single…

Geophysics · Physics 2020-04-03 William W. Symes

Lately a new approach to Extended Reality (XR), denoted as XR-RF, has been proposed which is realized by combining Radio Frequency (RF) Imaging and programmable wireless environments (PWEs). RF Imaging is a technique that aims to detect…

Object detection in remote sensing is a crucial computer vision task that has seen significant advancements with deep learning techniques. However, most existing works in this area focus on the use of generic object detection and do not…

Computer Vision and Pattern Recognition · Computer Science 2023-07-14 Abdelbadie Belmouhcine , Jean-Christophe Burnel , Luc Courtrai , Minh-Tan Pham , Sébastien Lefèvre

One of the challenges in phase measuring deflectometry is to retrieve the wavefront from objects that present discontinuities or non-differentiable gradient fields. Here, we propose the integration of such gradients fields based on an…

Numerical Analysis · Mathematics 2023-06-02 Ricardo Legarda-Saenz , Jorge L. Flores , Manuel Servin , Anabel Martin-Gonzalez

The main objective of the present project is to explore the viability of an adaptive optics control system based exclusively on Field Programmable Gate Arrays (FPGAs), making strong use of their parallel processing capability. In an…

Instrumentation and Methods for Astrophysics · Physics 2018-07-03 Avinash Surendran , Mahesh P. Burse , A. N. Ramaprakash , Padmakar Parihar