Extinction controlled adaptive phase-mask coronagraph

TL;DR

This paper introduces an adaptive, polarization interferometry-based phase-mask coronagraph that dynamically optimizes nulling efficiency, reduces sensitivity to aberrations, and compensates for manufacturing and chromatic errors, enhancing high-contrast imaging.

Contribution

It presents a novel adaptive phase-mask coronagraph concept using polarization interferometry for improved robustness and achromatic performance, demonstrated through numerical simulations.

Findings

Numerical simulations show improved nulling efficiency.

The adaptive system reduces sensitivity to tip-tilt errors.

Potential for use with current and next-generation adaptive optics.

Abstract

Context. Phase-mask coronagraphy is advantageous in terms of inner working angle and discovery space. It is however still plagued by drawbacks such as sensitivity to tip-tilt errors and chromatism. A nulling stellar coronagraph based on the adaptive phase-mask concept using polarization interferometry is presented in this paper. Aims. Our concept aims at dynamically and achromatically optimizing the nulling efficiency of the coronagraph, making it more immune to fast low-order aberrations (tip-tilt errors, focus, ...). Methods. We performed numerical simulations to demonstrate the value of the proposed method. The active control system will correct for the detrimental effects of image instabilities on the destructive interference. The mask adaptability both in size, phase and amplitude also compensates for manufacturing errors of the mask itself, and potentially for chromatic effects. Liquid-crystal properties are used to provide variable transmission of an annulus around the phase mask, but also to achieve the achromatic {\pi} phase shift in the core of the PSF by rotating the polarization by 180 degrees. Results. We developed a new concept and showed its practical advantages using numerical simulations. This new adaptive implementation of the phase-mask coronagraph could advantageously be used on current and next-generation adaptive optics systems, enabling small inner working angles without compromising contrast.