Title: Implementing focal-plane phase masks optimized for real telescope apertures with SLM-based digital adaptive coronagraphy,
Abstract: 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.