An aperture masking mode for the MICADO instrument

TL;DR

This paper discusses the development of an aperture masking mode for MICADO, a near-infrared camera on the European ELT, focusing on stability and technical design choices for high-contrast imaging.

Contribution

It introduces a pupil masking approach for MICADO that enhances optical transfer function stability, with detailed design considerations and trade-offs.

Findings

Preliminary designs of pupil masks are presented.

Trade-offs and technical choices are explained.

The approach aims to improve high contrast imaging stability.

Abstract

MICADO is a near-IR camera for the Europea ELT, featuring an extended field (75" diameter) for imaging, and also spectrographic and high contrast imaging capabilities. It has been chosen by ESO as one of the two first-light instruments. Although it is ultimately aimed at being fed by the MCAO module called MAORY, MICADO will come with an internal SCAO system that will be complementary to it and will deliver a high performance on axis correction, suitable for coronagraphic and pupil masking applications. The basis of the pupil masking approach is to ensure the stability of the optical transfer function, even in the case of residual errors after AO correction (due to non common path errors and quasi-static aberrations). Preliminary designs of pupil masks are presented. Trade-offs and technical choices, especially regarding redundancy and pupil tracking, are explained.