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.

15 pages, 10 figures, accepted for publication in Optics Express feature issue "Recent Advances in Astrophotonics"

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Cited by in corpus (5)

• Imaging exoplanets with coronagraphic instruments
• SLM-based Active Focal-Plane Coronagraphy: Status and future on-sky prospects
• Active focal-plane coronagraphy with liquid-crystal spatial-light modulators: Broadband contrast performance in the visible
• A simple optimized amplitude pupil mask for attempting to direct imaging of Proxima b with SPHERE/ZIMPOL at VLT
• SLM-based Digital Adaptive Coronagraphy: Current Status and Capabilities