Future space observatories will likely have segmented primaries, causing diffraction effects that reduce coronagraph performance. Reflective binary pupil apodizer masks can mitigate these, with the metamaterial black silicon (BSi) showing promise as a strong absorber. To bring contrast ratios to the 10−10 level as needed to observe Earth-like exoplanets, feature sizes on these BSi masks will need to be less than 5 microns when paired with MEMS (micro-electromechanical systems) deformable mirrors. As scalar diffraction cannot reliably model this feature size, we developed a Finite-Difference Time-Domain (FDTD) model of BSi masks using Meep software. We characterize the FDTD-derived polarization-dependent bidirectional reflectance distribution function of BSi and discuss the model's shortcomings.
@article{arxiv.2406.19028,
title = {Black Silicon BRDF and Polarization for Coronagraphic Pupil Masks},
author = {Emory L. Jenkins and Ramya M. Anche and Kyle J. Van Gorkom and A. J. Eldorado Riggs and Ewan S. Douglas},
journal= {arXiv preprint arXiv:2406.19028},
year = {2024}
}
Comments
8 pages, 10 figures, submitted to SPIE Astronomical Telescopes and Instrumentation (AS24)