End to End Simulation of AO-assisted coronagraphic differential imaging: estimation of performance for SPHERE

TL;DR

This paper presents an end-to-end Fourier optics simulation of the SPHERE instrument, assessing its performance and sensitivity to various parameters for high-contrast exoplanet imaging.

Contribution

It introduces a comprehensive Fourier optics model of SPHERE, enabling detailed sensitivity analysis and performance estimation for the instrument's main observing mode.

Findings

Performance varies with wavefront errors and alignment

Contrast performance depends on flux levels

Sensitivity analysis guides instrument specifications

Abstract

SPHERE (Spectro Polarimetric High contrast Exoplanet REsearch), the planet finder instrument for the VLT is designed to study relatively bright extrasolar giant planets around young or nearby stars. SPHERE is a set of three instruments fed by the same AO-system, two of them share the same coronagraph. This complex system has been modeled with Fourier Optics to investigate the performance of the whole instrument. In turns, this end-to-end model was useful to analyze the sensitivity to various parameters (WFE, alignment of the coronagraph, differential aberrations) and to put some specifications on the sub-systems. This paper presents some example of sensitivity analysis and some contrast performance of the instruments as a function of the flux for the main observing mode of SPHERE: the Dual Band Imaging (DBI), equivalent to the Spectral Differential Imaging technique.