A broadband vector vortex coronagraph for SCExAO/VAMPIRES (Conference Presentation)

Visible light high-contrast imaging is exciting because of the possibility to detect accretion tracers like Hα at extremely small separations, but this is complicated by high atmospheric turbulence. To overcome this limit, AO188 is being upgraded and SCExAO/VAMPIRES has received more sensitive cameras and a multi-band imaging mode. To take advantage of these upgrades, a high-performance broadband coronagraph is needed. In this paper, we report on the installation of a liquid-crystal double-grating vector-vortex coronagraph with these properties in October 2023. We detail the high-quality manufacturing of the mask by Colorlink Japan, ltd and show its performance characterization with an internal source and on-sky using the multi-band imaging mode, simultaneously imaging four wavelength bands. We describe our efforts to calibrate the mask for polarimetry, review possibilities for an upgrade for simultaneous multi-band focal-plane wavefront sensing, and discuss the performance in the context of the balloon-borne PICTURE-D mission and future space missions.