15,952 research outputs found
Direct imaging with highly diluted apertures. I. Field of view limitations
Future optical interferometric instrumentation mainly relies on the
availability of an efficient cophasing system: once available, what has so far
postponed the relevance of direct imaging with an interferometer will vanish.
This paper focuses on the actual limits of snapshot imaging, inherent to the
use of a sparse aperture: the number of telescopes and the geometry of the
array impose the maximum extent of the field of view and the complexity of the
sources. A second limitation may arise from the beam combination scheme.
Comparing already available solutions, we show that the so called
hypertelescope mode (or densified pupil) is ideal. By adjusting the direct
imaging field of view to the useful field of view offered by the array, the
hypertelescope makes an optimal use of the collected photons. It optimizes
signal to noise ratio, drastically improves the luminosity of images and makes
the interferometer compatible with coronagraphy, without inducing any loss of
useful field of view.Comment: 13 pages, 6 figures, accepted for publication in MNRAS.
Full-resolution version available at
http://www.obs-hp.fr/~lardiere/publi/2006-Lardiere-MNRAS.pd
Multi-Color Imaging of Magnetic Co/Pt Multilayers
We demonstrate for the first time the realization of a spatial resolved two color, element-specific imaging experiment at the free-electron laser facility FERMI. Coherent imaging using Fourier transform holography was used to achieve direct real space access to the nanometer length scale of magnetic domains of Co/Pt heterostructures via the element-specific magnetic dichroism in the extreme ultraviolet spectral range. As a first step to implement this technique for studies of ultrafast phenomena we present the spatially resolved response of magnetic domains upon femtosecond laser excitation
AAO Starbugs: software control and associated algorithms
The Australian Astronomical Observatory's TAIPAN instrument deploys 150
Starbug robots to position optical fibres to accuracies of 0.3 arcsec, on a 32
cm glass field plate on the focal plane of the 1.2 m UK-Schmidt telescope. This
paper describes the software system developed to control and monitor the
Starbugs, with particular emphasis on the automated path-finding algorithms,
and the metrology software which keeps track of the position and motion of
individual Starbugs as they independently move in a crowded field. The software
employs a tiered approach to find a collision-free path for every Starbug, from
its current position to its target location. This consists of three
path-finding stages of increasing complexity and computational cost. For each
Starbug a path is attempted using a simple method. If unsuccessful,
subsequently more complex (and expensive) methods are tried until a valid path
is found or the target is flagged as unreachable.Comment: 10 pages, to be published in Proc. SPIE 9913, Software and
Cyberinfrastructure for Astronomy IV; 201
The Orbital Maneuvering Vehicle Training Facility visual system concept
The purpose of the Orbital Maneuvering Vehicle (OMV) Training Facility (OTF) is to provide effective training for OMV pilots. A critical part of the training environment is the Visual System, which will simulate the video scenes produced by the OMV Closed-Circuit Television (CCTV) system. The simulation will include camera models, dynamic target models, moving appendages, and scene degradation due to the compression/decompression of video signal. Video system malfunctions will also be provided to ensure that the pilot is ready to meet all challenges the real-world might provide. One possible visual system configuration for the training facility that will meet existing requirements is described
An instrumental puzzle: the modular integration of AOLI
The Adaptive Optics Lucky Imager, AOLI, is an instrument developed to deliver
the highest spatial resolution ever obtained in the visible, 20 mas, from
ground-based telescopes. In AOLI a new philosophy of instrumental prototyping
has been applied, based on the modularization of the subsystems. This modular
concept offers maximum flexibility regarding the instrument, telescope or the
addition of future developments.Comment: 10 pages, 8 figures, Proc. SPIE 9908, Ground-based and Airborne
Instrumentation for Astronomy VI, 99082Z (August 9, 2016
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