Cascade adaptive optics: contrast performance analysis of a two-stage controller by numerical simulations

The contrast performance of current extreme adaptive optics (XAO) systems can be improved by adding a second AO correction stage featuring its own wavefront sensor (WFS), deformable mirror (DM), and real-time controller. We develop dynamical model for such cascade (CAO) system with two stages each controlled standard integrator study control properties. how configuration improve an existing without modifying the first stage. analyze CAO architecture in general show part disturbance is transferred from low to high temporal frequencies nefarious effect overshoot suggest possible ways mitigate this. also carry out numerical simulations particular case using Shack–Hartmann WFS smaller DM running at higher framerate reduce error. In this case, we demonstrate that improves imaging one order magnitude shortens decorrelation time atmospheric turbulence speckles even greater factor. results presents promising relatively simple way upgrade some XAO achieve contrasts fostering large number science including direct exoplanets.