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This tutorial gives a general introduction to optical and infrared interferometry, specifically addressing two questions: `Can I use VLTI to observe my favourite object?' and `What will it tell me?' The observables measured by an…

Astrophysics · Physics 2007-05-23 Timothy R. Bedding

We present a new approach for image reconstruction and weak lensing measurements with interferometers. Based on the shapelet formalism presented in Refregier (2001), object images are decomposed into orthonormal Hermite basis functions. The…

Astrophysics · Physics 2009-11-06 Tzu-Ching Chang , Alexandre Refregier

The VITRUV project has the objective to deliver milli-arcsecond spectro-images of the environment of compact sources like young stars, active galaxies and evolved stars to the community. This instrument of the VLTI second generation based…

The development of high-contrast capabilities has long been recognized as one of the top priorities for the VLTI. As of today, the VLTI routinely achieves contrasts of a few 10$^{-3}$ in the near-infrared with PIONIER (H band) and GRAVITY…

GRAVITY acquisition camera implements four optical functions to track multiple beams of Very Large Telescope Interferometer (VLTI): a) pupil tracker: a $2 \times 2$ lenslet images four pupil reference lasers mounted on the spiders of…

Most statistical tools used to characterize the complex structures of the interstellar medium can be related to the power spectrum, and therefore to the Fourier amplitudes of the observed fields. To tap into the vast amount of information…

Astrophysics · Physics 2009-11-11 Francois Levrier , Edith Falgarone , Francois Viallefond

Space telescopes for solar hard X-ray imaging provide observations made of sampled Fourier components of the incoming photon flux. The aim of this study is to design an image reconstruction method relying on enhanced visibility…

Instrumentation and Methods for Astrophysics · Physics 2021-10-13 Emma Perracchione , Paolo Massa , Anna Maria Massone , Michele Piana

Long baseline diffraction-limited optical aperture synthesis technology by interferometry plays an important role in scientific study and practical application. In contrast to amplitude (phase) interferometry, intensity interferometry --…

Context. With the arrival of the next generation of ground-based imaging interferometers combining from 4 to possibly 6 telescopes simultaneously, there is also a strong need for a new generation of fringe trackers able to cophase such…

Instrumentation and Methods for Astrophysics · Physics 2015-05-27 N. Blind , O. Absil , J. -B. Lebouquin , J. -P. Berger , A. Chelli

Imaging objects with high relative permittivity and large electrical size remains a challenging problem in the field of inverse scattering. In this work we present a phaseless inverse scattering method that can accurately image and…

Applied Physics · Physics 2021-10-08 Amartansh Dubey , Samruddhi Deshmukh , Li Pan , Xudong Chen , Ross Murch

High precision astrometric Space Very Long Baseline Interferometry (S-VLBI) at the low end of the conventional frequency range, i.e. 20cm, is a requirement for a number of high priority science goals. These are headlined by obtaining…

Instrumentation and Methods for Astrophysics · Physics 2015-06-15 R. Dodson , M. Rioja , Y. Asaki , H. Imai , X. -Y. Hong , Z. Shen

Many technologies have been developed to help improve spatial resolution of observational images for ground-based solar telescopes, such as adaptive optics (AO) systems and post-processing reconstruction. As any AO system correction is only…

Instrumentation and Methods for Astrophysics · Physics 2017-01-04 Xue-bao Li , Zhong Liu , Feng Wang , Zhen-yu Jin , Yong-yuan Xiang , Yan-fang Zheng

The Very Large Telescope Interferometer is one of the most proficient observatories in the world for high angular resolution. Since its first observations, it has hosted several interferometric instruments operating in various bandwidths in…

In this white paper, we propose an upgrade to the Very Large Telescope Interferometer (VLTI) consisting of the addition of a new 8m Unit Telescope (UT5). The primary goal of this upgrade is to optimise the VLTI for exoplanet detection by…

Instrumentation and Methods for Astrophysics · Physics 2025-12-22 Óscar Carrión-González , Sylvestre Lacour , Mathias Nowak

The problem of phaseless aperture synthesis is of current interest in phase-unstable VLBI with a small number of elements when either the use of closure phases is not possible (a two-element interferometer) or their quality and number are…

Astrophysics · Physics 2009-11-10 Anisa T. Bajkova

The capabilities of the Global mm-VLBI Array are summarized and demonstrated through actual images from our monitoring of extragalactic radio jets. This sensitive 3mm-VLBI interferometer is able to provide images of up to 50 microarcseconds…

This tutorial paper describes the problem of image reconstruction from interferometric data with a particular focus on the specific problems encountered at optical (visible/IR) wavelengths. The challenging issues in image reconstruction…

Instrumentation and Methods for Astrophysics · Physics 2011-04-20 Éric Thiébaut , Jean-François Giovannelli

The ELTI concept capitalizes on recent breakthroughs in large-format SPAD (Single-Photon Avalanche Diode) imaging sensors, combining them with the unprecedented collecting area and segmented architecture of the ELT to deliver a…

Instrumentation and Methods for Astrophysics · Physics 2026-03-09 Francisco Prada , Enrique Perez , Sergio Fernandez-Acosta , Km Nitu Rai , Joel Sanchez-Bermudez

Interferometric closure invariants, constructed from triangular loops of mixed Fourier components, capture calibration-independent information on source morphology. While a complete set of closure invariants is directly obtainable from…

Instrumentation and Methods for Astrophysics · Physics 2024-11-20 Samuel Lai , Nithyanandan Thyagarajan , O. Ivy Wong , Foivos Diakogiannis , Lucas Hoefs

The next generation of solar telescopes will enable us to resolve the fundamental scales of the solar atmosphere, i.e., the pressure scale height and the photon mean free path. High-resolution observations of small-scale structures with…

Instrumentation and Methods for Astrophysics · Physics 2015-05-18 C. Denker