Performance evaluation of mid-IR vortex coronagraphs with centrally obscured segmented pupils
2015 (English)Conference paper, Poster (Refereed)
In its original design, the E-ELT/Metis instrument envisages a vortex coronagraph in the mid-IR regime for detection and characterization of exoplanets, with a contrast of 1e-4 at 2 lambda/D (~40 mas in L band). The AGPM (Annular Groove Phase Mask) is a vortex phase mask with impressive characteristics: small inner working angle, high throughput, achromaticity. A non-perfectly circular pupil and non-flat input wavefront result in a starlight leakage, degrading the performance of the vortex coronagraph. In this work, we present end-to-end performance simulations using Fourier optical propagation to determine the quality of the starlight rejection obtained with an infrared vortex coronagraph. We first analyse the performance facing E-ELT pupil variations (segmentations, central obscuration, spiders, missing segments), then pointing jitter and random adaptive optics residual phase screens are introduced to derive more realistic performance. Finally, more advanced concepts of the infrared vortex coronagraph are presented, in order to compensate for performance degradation.
Place, publisher, year, edition, pages
Engineering and Technology Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:uu:diva-295132OAI: oai:DiVA.org:uu-295132DiVA: diva2:933039
AO4ELT4 International Conference, 25-30 October, Lake Arrowhead, California, USA