In 1931, French astronomer Bernard Lyot suggested that placing a beam stop in the center of the Fourier plane of a telescope allows observing faint objects nearby on-axis bright sources. This opened a new chapter in astronomical imaging called coronagraphy. Since then various techniques have been proposed and implemented experimentally. In particular, it was shown that pure phase masks, instead of amplitude ones, is an efficient way to reject on-axis light. Since one decade, there is a growing interest in spiraling phase (optical vortex) masks that may create of a nodal area at the exit pupil plane of the telescope outside which on-axis light is rejected. Such optical vortex coronagraphy implies the development of singular phase masks endowed with well defined topological properties. To this aim, nowadays nanofabrication tools are a prime choice, which includes liquid crystal photo-alignment technology. Here we show that spontaneously occurring liquid crystal topological defects offer a smart alternative to optical vortex phase masks. Our first experimental smart coronagraphy observations will be presented and discussed.

Date Published: 2 November 2016
PDF: 1 pages
Proc. SPIE 9940, Liquid Crystals XX, 99400D (2 November 2016); doi: 10.1117/12.2237079

Published in SPIE Proceedings Vol. 9940:
Liquid Crystals XX
Iam Choon Khoo, Editor(s)