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Coronagraph focal-plane phase masks based on photonic crystal technology: recent progress and observational strategy

Show simple item record Murakami, Naoshi Nishikawa, Jun Traub, Wesley A. Mawet, Dimitri Moody, Dwight C. Kern, Brian D. Trauger, John T. Serabyn, Eugene Hamaguchi, Shoki Oshiyama, Fumika Sakamoto, Moritsugu Ise, Akitoshi Oka, Kazuhiko Baba, Naoshi Murakami, Hiroshi Tamura, Motohide 2013-03-15T22:58:36Z 2013-03-15T22:58:36Z 2012-07-01
dc.identifier.citation SPIE Astronomical Telescopes+Instrumentation, Amsterdam, Netherlands, July 1-6, 2012 en_US
dc.identifier.clearanceno 12-2713
dc.description.abstract Photonic crystal, an artificial periodic nanostructure of refractive indices, is one of the attractive technologies for coronagraph focal-plane masks aiming at direct imaging and characterization of terrestrial extrasolar planets. We manufactured the eight-octant phase mask (8OPM) and the vector vortex mask (VVM) very precisely using the photonic crystal technology. Fully achromatic phase-mask coronagraphs can be realized by applying appropriate polarization filters to the masks. We carried out laboratory experiments of the polarization-filtered 8OPM coronagraph using the High-Contrast Imaging Testbed (HCIT), a state-of-the-art coronagraph simulator at the Jet Propulsion Laboratory (JPL). We report the experimental results of 10-8-level contrast across several wavelengths over 10% bandwidth around 800nm. In addition, we present future prospects and observational strategy for the photonic-crystal mask coronagraphs combined with differential imaging techniques to reach higher contrast. We proposed to apply a polarization-differential imaging (PDI) technique to the VVM coronagraph, in which we built a two-channel coronagraph using polarizing beam splitters to avoid a loss of intensity due to the polarization filters. We also proposed to apply an angular-differential imaging (ADI) technique to the 8OPM coronagraph. The 8OPM/ADI mode avoids an intensity loss due to a phase transition of the mask and provides a full field of view around central stars. We present results of preliminary laboratory demonstrations of the PDI and ADI observational modes with the phase-mask coronagraphs. en_US
dc.description.sponsorship NASA/JPL en_US
dc.language.iso en_US en_US
dc.publisher Pasadena, CA : Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2012. en_US
dc.subject high-contrast imaging en_US
dc.subject extrasolar planets en_US
dc.subject photonic crystal en_US
dc.subject coronagraphy en_US
dc.subject eight-octant phase mask en_US
dc.subject vector vortex mask en_US
dc.subject polarization en_US
dc.title Coronagraph focal-plane phase masks based on photonic crystal technology: recent progress and observational strategy en_US
dc.type Preprint en_US

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