Closed-loop performance comparison of different probe shapes, measured in experiments on THD2, as a function of probe intensity in the DH, scaled by 10⁻⁶. The contrast was measured in the range 3–9 λ/D. The plot shows the best achieved DH mean contrast for three shapes of probes: classic sinc-sinc-sine probes (blue circles), single-actuator probes (orange crosses), and sharp sinc probes (green squares). Single-actuator probes maintain consistent performance up to higher probe intensities with minimal contrast degradation, while classic sinc probes degrade significantly at higher intensities. Sharp sinc probes perform in between the other two, showing better resilience than classic sinc probes, but not as robust as single-actuator probes. No DH loop was recorded for single-actuator probes scaled up ×2 and ×3 in amplitude. The slightly unequal starting points at the initial amplitude come from the level of contrast uncertainty originating in drifts and environmental variations of the testbed, which is on the order of 10⁻⁸ for the mean contrast.