An H-band Vector Vortex Coronagraph for the Subaru Coronagraphic Extreme-Adaptive Optics System

TL;DR

This paper presents the development, installation, and on-sky testing of an H-band vector vortex coronagraph on the Subaru Telescope's SCExAO system, demonstrating high-contrast imaging capabilities for exoplanet detection.

Contribution

It introduces a new H-band vector vortex coronagraph for the Subaru SCExAO system and provides detailed performance analysis and on-sky results, including exoplanet imaging.

Findings

Successful installation and performance of the vector vortex coronagraph.

High-contrast imaging achieved, including detection of ndromedae b.

Signal-to-noise ratio above 100 in less than 10 minutes.

Abstract

The vector vortex is a coronagraphic imaging mode of the recently commissioned Subaru Coronagraphic Extreme-Adaptive Optics (SCExAO) platform on the 8-m Subaru Telescope. This multi-purpose high-contrast visible and near-infrared (R- to K-band) instrument is not only intended to serve as a VLT-class "planet-imager" instrument in the Northern hemisphere, but also to operate as a technology demonstration testbed ahead of the ELTs-era, with a particular emphasis on small inner-working angle (IWA) coronagraphic capabilities. The given priority to small-IWA imaging led to the early design choice to incorporate focal-plane phase-mask coronagraphs. In this context, a test H-band vector vortex liquid crystal polymer waveplate was provided to SCExAO, to allow a one-to-one comparison of different small-IWA techniques on the same telescope instrument, before considering further steps. Here we present a detailed overview of the vector vortex coronagraph, from its installation and performances on the SCExAO optical bench, to the on-sky results in the extreme AO regime, as of late 2016/early 2017. To this purpose, we also provide a few recent on-sky imaging examples, notably high-contrast ADI detection of the planetary-mass companion \kappa Andromedae b, with a signal-to-noise ratio above 100 reached in less than 10 mn exposure time.