Examples of wavefront differences from reference as reconstructed by the ZWFS (top) and of DH images (bottom) during the contrast stabilization experiment with the calibration around flat maps. The iterations at 0, 400, and 800 s are from the open-loop experiment. The loop is closed after 900 s. In this experiment, we are adding “artificial drifts” in the form of low-order aberration random walk added to the continuous DM. At the end of the open-loop phase (900 s), the added aberration is about 20 nm RMS. At the end of the closed-loop phase (1800 s), the added aberration is about 25 nm RMS. This experiment also corresponds to the nominal turbulence regime (“low”).