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Compressive sensing claims that the sparse signals can be reconstructed exactly from many fewer measurements than traditionally believed necessary. One of issues ensuring the successful compressive sensing is to deal with the…

Information Theory · Computer Science 2009-03-31 Lianlin Li , Fang Li

Accurate polarimetric calibration of the radio pulse profiles from pulsars is crucial for studying their radiation properties at these wavelengths. Inaccurate calibration can also distort recorded pulse profiles, introducing noise in time…

High Energy Astrophysical Phenomena · Physics 2023-10-11 Lucas Guillemot , Ismaël Cognard , Willem van Straten , Gilles Theureau , Eric Gérard

Radio telescopes are used to accurately measure the time of arrival (ToA) of radio pulses in pulsar timing experiments that target mostly millisecond pulsars (MSPs) due to their high rotational stability. This allows for detailed study of…

Instrumentation and Methods for Astrophysics · Physics 2015-09-09 Griffin Foster , Aris Karastergiou , Remi Paulin , Tobia Carozzi , Simon Johnston , Willem van Straten

Inverse imaging problems that are ill-posed can be encountered across multiple domains of science and technology, ranging from medical diagnosis to astronomical studies. To reconstruct images from incomplete and distorted data, it is…

Image and Video Processing · Electrical Eng. & Systems 2023-11-30 Cesar F. Caiafa , Ramiro M. Irastorza

Taking advantage of the advances in array detector technology, an imaging polarimeter (IMPOL) has been constructed for measuring linear polarization in the wavelength band from 400-800 nm. It makes use of a Wollaston prism as the analyser…

Astrophysics · Physics 2009-09-15 A. N. Ramaprakash , Ranjan Gupta , A. K. Sen , S. N. Tandon

Polarization-resolved control and measurement of the optical field are essential for a wide range of photonic systems, including coherent communication, polarimetric sensing, and quantum information processing. We present a photonic…

We reformulate the gain correction problem of the radio interferometry as an optimization problem with regularization, which is solved efficiently with an iterative algorithm. Combining this new method with our previously proposed imaging…

Instrumentation and Methods for Astrophysics · Physics 2024-12-05 Shiro Ikeda , Takeshi Nakazato , Takashi Tsukagoshi , Tsutomu T. Takeuchi , Masayuki Yamaguchi

Polarization cameras can capture multiple polarized images with different polarizer angles in a single shot, bringing convenience to polarization-based downstream tasks. However, their direct outputs are color-polarization filter array…

Computer Vision and Pattern Recognition · Computer Science 2025-04-23 Shuangfan Zhou , Chu Zhou , Youwei Lyu , Heng Guo , Zhanyu Ma , Boxin Shi , Imari Sato

Sparse aperture masking (SAM) interferometry combined with Adaptive Optics (AO) is a technique that is uniquely suited to investigate structures near the diffraction limit of large telescopes. The strengths of the technique are a robust…

Instrumentation and Methods for Astrophysics · Physics 2015-06-04 J. Sanchez-Bermudez , R. Schoedel , A. Alberdi , J. U. Pott

Reconstructing an object's geometry and appearance from multiple images, also known as inverse rendering, is a fundamental problem in computer graphics and vision. Inverse rendering is inherently ill-posed because the captured image is an…

Computer Vision and Pattern Recognition · Computer Science 2022-03-28 Akshat Dave , Yongyi Zhao , Ashok Veeraraghavan

We present a high-precision temporal-spatial phase-demodulation algorithm for phase-shifting interferometry (PSI) affected by random/systematic phase-stepping errors. Laser interferometers in standard optical-shops suffer from several error…

Signal Processing · Electrical Eng. & Systems 2019-12-11 Manuel Servin , Moises Padilla , Guillermo Garnica , Gonzalo Paez

Context. Circumstellar disks and self-luminous giant exoplanets or companion brown dwarfs can be characterized through direct-imaging polarimetry at near-infrared wavelengths. SPHERE/IRDIS at the Very Large Telescope has the capabilities to…

Calibrating out per-antenna signal chain effects is an essential step in analyzing radio interferometric data. For drift-scanning arrays, robustly calibrating the data is especially challenging due to the lack of the ability to track a…

Instrumentation and Methods for Astrophysics · Physics 2026-02-09 Robert Pascua , Jonathan Sievers , Adrian Liu

In this paper, we introduce an iterative speckle filtering method for polarimetric SAR (PolSAR) images based on the bilateral filter. To locally adapt to the spatial structure of images, this filter relies on pixel similarities in both…

Computer Vision and Pattern Recognition · Computer Science 2013-11-04 Olivier D'Hondt , Stéphane Guillaso , Olaf Hellwich

Radio-astronomical observations are increasingly contaminated by interference, and suppression techniques become essential. A powerful candidate for interference mitigation is adaptive spatial filtering. We study the effect of spatial…

Astrophysics · Physics 2014-10-13 Amir Leshem , Alle-Jan van der Veen

We characterize the problem of artificial polarization for the Submillimeter High Angular Resolution Polarimeter (SHARP) through the use of simulated data and observations made at the Caltech Submillimeter Observatory (CSO). These…

Astrophysics · Physics 2009-11-13 Michael Attard , Martin Houde , Giles Novak , John E. Vaillancourt

Aims: We address two issues for the adoption of convex optimization in radio interferometric imaging. First, a method for a fine resolution setup is proposed which scales naturally in terms of memory usage and reconstruction speed. Second,…

Instrumentation and Methods for Astrophysics · Physics 2025-01-22 Adrian Jarret , Sepand Kashani , Joan Rué-Queralt , Paul Hurley , Julien Fageot , Matthieu Simeoni

Radio interferometry has always faced the problem of incomplete sampling of the Fourier plane. A possible remedy can be found in the promising new theory of compressed sensing (CS), which allows for the accurate recovery of sparse signals…

Instrumentation and Methods for Astrophysics · Physics 2015-12-22 Clara Fannjiang

A sparse recovery approach for direction finding in partly calibrated arrays composed of subarrays with unknown displacements is introduced. The proposed method is based on mixed nuclear norm and 1 norm minimization and exploits…

Information Theory · Computer Science 2018-02-14 Christian Steffens , Marius Pesavento

Performance of digitally beamformed phased arrays relies on accurate calibration of the array by obtaining gains of each antenna in the array. The stations of the Square Kilometer Array-Low (SKA-Low) are such digital arrays, where the…

Instrumentation and Methods for Astrophysics · Physics 2024-01-17 Jishnu N. Thekkeppattu , Randall B. Wayth , Marcin Sokolowski
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