Band-Limited Coronagraphs using a Halftone-dot process: design guidelines, manufacturing, and laboratory results

TL;DR

This paper explores the use of a microdots halftone-dot process to design, manufacture, and test band-limited coronagraphs for direct exoplanet imaging, demonstrating promising laboratory results for ground-based telescopes.

Contribution

It introduces a novel application of the microdots technique for fabricating band-limited coronagraph masks and provides design guidelines and laboratory validation.

Findings

Microdots technique effectively produces band-limited coronagraph masks.

Laboratory results confirm the suitability of microdots for ground-based exoplanet imaging.

Design guidelines facilitate future manufacturing of coronagraph components.

Abstract

The Exo-Planet Imaging Camera and Spectrograph (EPICS) for the future 42-meter European-Extremely Large Telescope, will enable direct images, and spectra for both young and old Jupiter-mass planets in the infrared. To achieve the required contrast, several coronagraphic concepts -- to remove starlight -- are under investigation: conventional pupil apodization (CPA), apodized-pupil Lyot coronagraph (APLC), dual-zone coronagraph (DZC), four-quadrants phase mask (FQPM), multi-stages FQPM, annular groove phase mask (AGPM), high order optical vortex (OVC), and band-limited coronagraph (BLC). Recent experiment demonstrated the interest of an halftone-dot process -- namely microdots technique -- to generate the adequate transmission profile of pupil apodizers for CPA, APLC, and DZC concepts. Here, we examine the use of this technique to produce band-limited focal plane masks, and present guidelines for the design. Additionally, we present the first near-IR laboratory results with BLCs that confirm the microdots approach as a suitable technique for ground-based observations.