Direct imaging of exoplanets or circumstellar disk material requires extreme contrast at the 10-6 to 10-12 levels at < 100 mas angular separation from the star. Focal-plane mask (FPM) coronagraphic imaging has played a key role in this field, taking advantage of progress in Adaptive Optics on ground-based 8+m class telescopes. However, large telescope entrance pupils usually consist of complex, sometimes segmented, non-ideal apertures, which include a central obstruction for the secondary mirror and its support structure. In practice, this negatively impacts wavefront quality and coronagraphic performance, in terms of achievable contrast and inner working angle. Recent theoretical works on structured darkness have shown that solutions for FPM phase profiles, optimized for non-ideal apertures, can be numerically derived. Here we present and discuss a first experimental validation of this concept, using reflective liquid crystal spatial light modulators as adaptive FPM coronagraphs.
@article{arxiv.1707.03256,
title = {Implementing focal-plane phase masks optimized for real telescope apertures with SLM-based digital adaptive coronagraphy},
author = {Jonas Kühn and Patapis Polychronis and Garreth Ruane and Xin Lu},
journal= {arXiv preprint arXiv:1707.03256},
year = {2017}
}
Comments
15 pages, 10 figures, accepted for publication in Optics Express feature issue "Recent Advances in Astrophotonics"