A device for supplying radiant energy onto a printing substrate (14), including at least one radiant energy source (10) whose light (12) impinges on the printing substrate (14) on the path (16) of the printing substrate (14) through a printing press at a position (116) downstream of at least one printing nip (18) in a printing unit. The radiant energy source (10) emits light (12) having a peak-to-valley homogeneity of less than 15% in a direction transverse to the direction of the path (16) of the printing substrate (14).