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The Evanescent Wave Coronagraph (EvWaCo) is an achromatic coronagraph maskwith adjustable size over the spectral domain [600nm, 900nm] that will beinstalled at the Thai National Observatory. We present in this work thedevelopment of a bench to characterise its Extreme Adaptive Optics system (XAO)comprising a DM192 ALPAO deformable mirror (DM) and a 15x15 Shack-Hartmannwavefront sensor (SH-WFS). In this bench, the turbulence is simulated using arotating phase plate in a pupil plane. In general, such components are designedusing a randomly generated phase screen. Such single realisation does notnecessarily provide the wanted structure function. We present a solution todesign the printed pattern to ensure that the beam sees a strict and controlledKolmogorov statistics with the correct 2D structure function. This is essentialto control the experimental conditions in order to compare the bench resultswith the numerical simulations and predictions. This bench is further used todeeply characterise the full 27 mm pupil of the ALPAO DM using a 54x54 ALPAOSH-WFS. We measure the average shape of its influence functions as well as theinfluence function of each single actuator to study their dispersion. We studythe linearity of the actuator amplitude with the command as well as thelinearity of the influence function profile. We also study the actuator offsetsas well as the membrane shape at 0-command. This knowledge is critical to get aforward model of the DM for the XAO control loop.

Adaptive Optics system of the Evanescent Wave Coronagraph (EvWaCo): optimised phase plate and DM characterisation