The Evanescent Wave Coronagraph (EvWaCo) is an achromatic coronagraph mask with adjustable size over the spectral domain [600 nm, 900 nm] that will be installed at the Thai National Observatory. We present in this work the development of a bench to characterise its Extreme Adaptive Optics system (XAO) comprising a DM192 ALPAO deformable mirror (DM) and a 15x15 Shack-Hartmann wavefront sensor (SH-WFS). In this bench, the turbulence is simulated using a rotating phase plate in a pupil plane. In general, such components are designed using a randomly generated phase screen. Such single realisation does not necessarily provide the wanted structure function. We present a solution to design the printed pattern to ensure that the beam sees a strict and controlled Kolmogorov statistics with the correct 2D structure function. This is essential to control the experimental conditions in order to compare the bench results with the numerical simulations and predictions.This bench is further used to deeply characterise the full 27 mm pupil of the ALPAO DM using a 54 × 54 ALPAO SH-WFS. We measure the average shape of its inuence functions as well as the inuence function of each single actuator to study their dispersion. We study the linearity of the actuator amplitude with the command as well as the linearity of the inuence function prole. We also study the actuator osets as well as the membrane shape at 0-command. This knowledge is critical to get a forward model of the DM for the XAO control loop.

We present the results obtained with an end-to-end simulator of an Extreme Adaptive Optics (XAO) system control loop. It is used to predict its on-sky performances and to optimise the AO loop algorithms. It was rst used to validate a novel analytical model of the tting error, a limit due to the Deformable Mirror (DM) shape.Standard analytical models assume a sharp correction under the DM cuto frequency, disregarding the transition between the AO corrected and turbulence dominated domains. Our model account for the inuence function shape in this smooth transition. Then, it is well-known that Shack-Hartmann wavefront sensors (SH-WFS) have a limited spatial bandwidth, the high frequencies of the wavefront being seen as low frequencies. We show that this aliasing error can be partially compensated (both in terms of Strehl ratio and contrast) by adding priors on the turbulence statistics in the framework of an inverse problem approach. This represents an alternative to the standard additional optical lter used in XAO systems. In parallel to this numerical work, a bench was aligned to experimentally test the AO system and these new algorithms comprising a DM192 ALPAO deformable mirror and a 15×15 SH-WFS. We present the predicted performances of the AO loop based on end-to-end simulations.