Snapshot coronagraphy with an interferometer in space

Diluted arrays of many optical apertures will be able to provide high-resol ution snapshot images if the beams are combined according to the densified- pupil scheme. We show that the same principle can also provide coronagraphi c images, for detecting faint sources near a bright unresolved one. Recent refinements of coronagraphic techniques, i.e., the use of a phase mask, act ive apodization, and dark-speckle analysis, are also applicable for enhance d contrast. Implemented in the form of a proposed 50- to 500-m Exo-Earth Di scoverer array in space, the principle can serve to detect Earth-like exo-p lanets in the infrared. It can also provide images of faint nebulosity near stars, active galactic nuclei, and quasars, Calculations indicate that exo -planets are detectable amidst the zodiacal and exo-zodiacal emission faste r than with a Bracewell array of equivalent area, a consequence of the spat ial selectivity in the image, (C) 2000 Academic Press.