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Please use this identifier to cite or link to this item:
http://hdl.handle.net/2014/42888
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| Title: | Coronagraph focal-plane phase masks based on photonic crystal technology: recent progress and observational strategy |
| Authors: | 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 |
| Keywords: | high-contrast imaging
extrasolar planets
photonic crystal
coronagraphy
eight-octant phase mask
vector vortex mask
polarization |
| Issue Date: | 1-Jul-2012 |
| Publisher: | Pasadena, CA : Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2012. |
| Citation: | SPIE Astronomical Telescopes+Instrumentation, Amsterdam, Netherlands, July 1-6, 2012 |
| 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. |
| URI: | http://hdl.handle.net/2014/42888 |
| Appears in Collections: | JPL TRS 1992+
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