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5 October 2005 The four-quadrant ZOG and annular groove phase mask coronagraphs
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Phase mask coronagraphy is a technique aiming at accommodating both high dynamic and high angular resolution imaging of faint sources around bright objects such as exo-planets orbiting their parent stars or host galaxies around Active Galactic Nuclei. We present two new phase mask coronagraphs implemented with subwavelength diffractive optical elements consisting of optimized surface-relief gratings. The first one is an evolution of the Four Quadrant Phase Mask coronagraph, which resolves the π phase shift chromaticity problem: the Four Quadrant Zeroth Order Grating (4QZOG). The second one is a totally new design consisting of an optical vortex induced by a space-variant grating: the Annular Groove Phase Mask (AGPM) coronagraph is fully symmetric and free from any "shaded zones". Some manufacturing hints are given.
© (2005) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Dimitri Mawet, Pierre Riaud, Olivier Absil, Jacques Baudrand, and Jean Surdej "The four-quadrant ZOG and annular groove phase mask coronagraphs", Proc. SPIE 5905, Techniques and Instrumentation for Detection of Exoplanets II, 59051N (5 October 2005);

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