ESCAPE project. CAPyBARA: a Roman Coronagraph simulator for post-processing methods development

TL;DR

This paper introduces CAPyBARA, a simulation pipeline for the Roman Coronagraph that models optical propagation, wavefront errors, and post-processing to enhance exoplanet imaging contrast.

Contribution

It develops the first version of a simulator integrating coronagraph modeling, wavefront error calibration, and post-processing, enabling performance testing of observing strategies for the Roman mission.

Findings

Simulated the coronagraph's optical propagation and dark-hole creation.

Analyzed the impact of quasi-static aberrations on contrast.

Performed initial post-processing with classical subtraction techniques.

Abstract

The Roman Coronagraph Instrument will be the first space facility equipped with deformable mirrors (DMs). These will lead to reach a contrast of $10^{-8}$ or better in a dark hole between $3-9 \lambda/D$. Post-processing techniques play an important role in increasing the contrast limits. Our work investigates how DMs can be used to calibrate the instrument response to controlled wavefront error maps and to improve the post-processing performance. To this goal, we are developing a simulation pipeline, CAPyBARA, that includes both a propagation model of the Coronagraph and a post-processing module and produces starlight subtracted images of a science target. This pipeline will allow us to investigate alternative observing strategies and test their performance for the Roman Coronagraph. Here we present the first version of the simulator: it currently reproduces the optical propagation, which consists in the hybrid Lyot coronagraph optical structure and dark-hole digging technique (Electric Field Conjugation coupled with $\beta$-bumping), the environment (quasi-static aberration) and the post-processing. With it, we mimic a Coronagraph Instrument observing sequence, which consists in first acquiring reference star data before slewing to the scientific target, and we investigate how the evolution of quasi-static aberrations deteriorate the contrast limit in the dark hole. We simulate a science target with planets at high contrast with their star and we perform a first post-processing analysis with classical subtraction techniques. Here we present the CAPyBARA simulator, as well as some first results. The next step will be to generate PSF libraries by injecting pre-calibrated probes on the DMs (in open loop) during the reference star acquisition and compute a PCA model. Later, we will compare the performance gain obtained with the modulated-DM reference library over standard approaches (RDI).