FFREE: a Fresnel-FRee Experiment for EPICS, the EELT planets imager

TL;DR

FFREE is an experimental optical setup designed to test and validate wavefront correction algorithms and adaptive optics techniques for high-contrast imaging, aiming to improve exoplanet detection by reducing static speckles.

Contribution

It introduces a Fresnel-free optical bench optimized for near-infrared high-contrast imaging, serving as a demonstrator for future EPICS instrumentation.

Findings

Successful wavefront measurement and compensation in NIR

Effective rejection of static speckles

Optimized for large bandwidth and AO control radius

Abstract

The purpose of FFREE - the new optical bench devoted to experiments on high-contrast imaging at LAOG - consists in the validation of algorithms based on off-line calibration techniques and adaptive optics (AO) respectively for the wavefront measurement and its compensation. The aim is the rejection of the static speckles pattern arising in a focal plane after a diffraction suppression system (based on apodization or coronagraphy) by wavefront pre-compensation. To this aim, FFREE has been optimized to minimize Fresnel propagation over a large near infrared (NIR) bandwidth in a way allowing efficient rejection up to the AO control radius, it stands then as a demonstrator for the future implementation of the optics that will be common to the scientific instrumentation installed on EPICS.