Open AccessDirect imaging with highly diluted apertures – I. Field‐of‐view limitations
Author(s) -
Lardière O.,
Martinache F.,
Patru F.
Publication year - 2007
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.11362.x
Subject(s) - physics , interferometry , optics , field of view , snapshot (computer storage) , astronomical interferometer , exit pupil , aperture (computer memory) , direct imaging , wavefront , aperture synthesis , pupil , computer science , acoustics , operating system
Future optical interferometric instrumentations mainly rely on the availability of an efficient cophasing system: once available, what has so far postponed the relevance of direct imaging to 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 (FOV) 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 FOV to the useful FOV 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 FOV.