Robustness to island effect errors between petals in phase maps simulated in the pupil plane in radians (left) and associated PSFs in logarithmic scale with the four designs (right). Three phases are considered: piston only-like errors, at the level observed on SPHERE before coating (top), tip-tilt-only errors, also at the SPHERE level (center), and combined piston-tip-tilt errors from the above rows (bottom).