SLM-based Active Focal-Plane Coronagraphy: Status and future on-sky prospects

TL;DR

This paper explores the use of liquid-crystal on silicon spatial light modulators as adaptive focal-plane phase masks in coronagraphy, presenting initial broadband contrast results and future instrument plans for high-contrast imaging.

Contribution

It introduces the concept of adaptive coronagraphs using SLMs, reports early broadband contrast performance, and details upcoming on-sky instrumentation for high-contrast imaging.

Findings

Early broadband contrast performance results obtained with SWATCHi.

Development of the PLACID instrument for the 4-m DAG observatory.

Plans for first light of the PLACID instrument in late 2022.

Abstract

We recently started to investigate how liquid-crystal on silicon (LCOS) spatial light modulator (SLM) would perform as programmable focal-plane phase mask (FPM) coronagraphs. Such "adaptive coronagraphs" could potentially help adapt to observing conditions, but also tackle specific science cases (e.g. binary stars). Active FPMs may play a role in the context of segmented telescope pupils, or to implement synchronous coherent differential imaging (CDI). We present a status update on this work, notably early broadband contrast performance results using our new Swiss Wideband Active Testbed for High-contrast imaging (SWATCHi) facility. Finally, we unveil the upcoming near-infrared PLACID instrument, the Programmable Liquid-crystal Adaptive Coronagraphic Imager for the 4-m DAG observatory in Turkey, with a first light planned for the end of the year 2022.