Image in logarithmic scale of a bright star used as AO reference and imaged on the LUCI N30 camera (plate scale = 15 mas pix⁻¹) at 1.65 μm. The three images (A), (B), and (C), from left to right, show the full PSF in a field of 1.9 arcsec; the three bottom images show the detail on the central peak with contour lines underlining low-order aberrations. Image (A): the NCPA correction is not applied and the seeing is 0.86 arcsec; the first diffraction ring shows lobes and the SR is 0.47. Image (B): the NCPA correction is applied with optical gain loop control and the seeing is still 0.86 arcsec, the first ring is round, and SR increased to 0.70. Image (C): the NCPA correction is applied with optical gain loop control and the seeing is 1.06 arcsec; the first ring is still round and the SR is 0.58.