A device for performing a measurement of a strand-shaped object comprises at least one transmission apparatus configured to emit measuring radiation onto the strand-shaped object, which reflects the measuring radiation. At least one receiving apparatus is configured to receive the measuring radiation reflected by the strand-shaped object. An evaluation apparatus is configured to determine at least one of (1) the diameter and (2) the outer contour of the strand-shaped object based on the measuring radiation received by the at least one receiving apparatus. At least one retroreflector is configured to surround at least a portion of the strand-shaped object and retroreflect at least some of the measuring radiation reflected by the strand-shaped object.