Proper motion diagram of the central field of the Quintuplet cluster. The circle around the origin indicates the selection of cluster members. L-band detected proper motion members are shown in green, while non-members are shown in red. Black sources are not detected in L′. Those sources are cluster members if located inside the green circle. L′ excess sources are marked as red diamonds, while Wolf-Rayet candidates are shown in blue (see Sect. 4.1). The right panel displays a zoom on the cluster selection and the median astrometric uncertainty for L-band detected members in the lower left corner.