Phase-Induced Amplitude Apodization on Centrally Obscured Pupils: Designand First Laboratory Demonstration for the Subaru Telescope Pupil

摘要

High-contrast coronagraphic imaging is challenging for telescopes with central obstructions andthick spider vanes, such as the Subaru Telescope. We present in this article the first laboratory demonstration of ahigh-efficiency PIAA-type coronagraph on such a pupil, using coronagraphic optics which will be part of the SubaruCoronagraphic Extreme-AO (SCExAO) system currently under assembly. Lossless pupil apodization is performedby a set of aspheric PIAA lenses specifically designed to also remove the pupil's central obstruction, coupled with aspider removal plate (SRP) which removes spider vanes by translating four parts of the pupil with tilted plane-parallel plates. An "inverse-PIAA" system, located after the coronagraphic focal plane mask, is used to removeoff-axis aberrations and deliver a wide field of view. Our results validate the concept adopted for the SCExAOsystem, and show that the Subaru Telescope pupil can be properly apodized for high-contrast coronagraphic imagingas close as≈1 λ/D with no loss of sensitivity. We also verify that off-axis aberrations in the system are in agreementwith theory, and that the inverse PIAA system recovers a wide usable field of view for exoplanet detection and disksimaging.