Apodized-pupil Lyot coronagraphs: multistage designs for extremely large telescopes

TL;DR

This paper evaluates multistage apodized-pupil Lyot coronagraphs for extremely large telescopes, finding that their theoretical advantages are negated by practical error sources, favoring the traditional single-stage design.

Contribution

The study provides a comprehensive analysis of multistage APLC designs for ELTs, including numerical simulations and laboratory experiments, demonstrating their limitations compared to single-stage configurations.

Findings

Multistage APLC performance is compromised by telescope error sources.

Numerical simulations show no significant gain over single-stage APLC.

Laboratory experiments support the numerical results.

Abstract

Earlier apodized-pupil Lyot coronagraphs (APLC) have been studied and developed to enable high-contrast imaging for exoplanet detection and characterization with present-day ground-based telescopes. With the current interest in the development of the next generation of telescopes, the future extremely large telescopes (ELTs), alternative APLC designs involving multistage configuration appear attractive. The interest of these designs for application to ELTs is studied. Performance and sensitivity of multistage APLC to ELT specificities are analyzed and discussed, taking into account several ineluctable coronagraphic telescope error sources by means of numerical simulations. Additionally, a first laboratory experiment with a two-stages-APLC in the near-infrared (H-band) is presented to further support the numerical treatment. Multistage configurations are found to be inappropriate to ELTs. The theoretical gain offered by a multistage design over the classical single-stage APLC is largely compromised by the presence of inherent error sources occurring in a coronagraphic telescope, and in particular in ELTs. The APLC remains an attractive solution for ELTs, but rather in its conventional single-stage configuration.