Example of a 20 × 20 pixel injection map done on the centering fiber with power meter. The sampling of 0.02 mrad pixel⁻¹ (0.5 λ/D at λ = 1.6 µm) is relatively coarse but sufficient to obtain an accurate estimate of the center position with a Gaussian fit (black cross). The spot is extended along one of the diagonals because of the projection effect of the pupil on the tip-tilt mirror, which is tilted by 45°.