2 August 2014 Simulated contrast performance of Phase Induced Amplitude Apodization (PIAA) coronagraph testbed
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Abstract
We evaluate the broadband contrast performance of a Phase Induced Amplitude Apodization (PIAA) coronagraph configuration through modeling and simulations. Broadband occulter mask design for PIAA-CMC is at an early stage, and a study of the effects of wavefront control on broadband contrast is needed to determine the level of control the occulting mask must achieve, so that the combination of occulter and wavefront control optimization meets contrast targets. The basic optical design of the PIAA coronagraph is the same as NASA’s High Contrast Imaging Testbed (HCIT) setup at the Jet Propulsion Laboratory (JPL). Using two deformable mirrors and a broadband wavefront sensing and control algorithm, we create a “dark hole” in the broadband point-spread function (PSF) with an inner working angle (IWA) of 2(fλ/D)sky. We evaluate a system using PIAA mirrors to create an apodization but not having any wavefront error at its exit-pupil, and having an obscured pupil and a new, 20-ring PIAACMC occulting mask. We also investigate the effect of Lyot stops of various sizes. For the configuration simulated here with the second-generation PIAA mirrors and early mask designs (which were not yet fully optimized), the best 10% broadband contrast value was ~6.1×10-8. This is a 2x improvement beyond what the coronagraph produces in the absence of wavefront control, which implies that further improvement must come from architecture changes or further mask optimization improvements.
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Erkin Sidick, Erkin Sidick, Brian Kern, Brian Kern, Ruslan Belikov, Ruslan Belikov, Andreas Kuhnert, Andreas Kuhnert, Stuart Shaklan, Stuart Shaklan, } "Simulated contrast performance of Phase Induced Amplitude Apodization (PIAA) coronagraph testbed", Proc. SPIE 9143, Space Telescopes and Instrumentation 2014: Optical, Infrared, and Millimeter Wave, 91430W (2 August 2014); doi: 10.1117/12.2055006; https://doi.org/10.1117/12.2055006
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