Throughput of the single-mode fibers as a function of tip-tilt offset of the source. On the top a two-dimensional throughput map is shown. On the bottom two slices through this map are plotted for several values for the mode field diameter of the single-mode fibers. Maximum throughput of ∼72% is reached at the center of a lenslet. On the edge of two microlens the throughput of two fibers have to be added to reach ∼30% throughput. The worst case is the triple-point at which the maximum throughput drops to ∼25%. A fiber mode field radius of w = 0.78λ/D achieves the highest throughput for all tip-tilt offsets.