S. Lacour, P. Tuthill, J. D. Monnier, T. Kotani, L. Gauchet, P. Labeye
Imaging the direct light signal from a faint exoplanet against the overwhelming glare of its host star presents one of the fundamental challenges to modern astronomical instrumentation. Achieving sufficient signal-to-noise for detection by direct imaging is limited by three basic physical processes: aberration of the wavefronts (both instrumental and atmospheric), photon noise, and detector noise. In this paper, we advance a novel optical setup which synthesizes the advantages of two different techniques: nulling interferometry to mitigate photon noise, and closure phase to combat optical aberrations. Our design, which employs technology from integrated optics and photonics, is intended to combine the advantageous aspects of both a coronagraph and a non-redundant interferometer. We show that such an instrument would allow readout noise limited detection of exoplanets, even in the presence of residual co-phasing errors. As a result, this concept would be ideal for space interferometry and for ground based observations of bright stellar hosts (apparent magnitude below 10). The method has applicability as a beam-combiner for a long baseline interferometer, or as a competitive alternative to coronagraphy on a large single-mirror telescope.
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http://arxiv.org/abs/1306.5184
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