Abstract: A device for structuring a surface of a through opening in a component, in particular a cylinder opening of a cylinder crankcase for an internal combustion engine. The device comprises a lance, which can be moved into the through opening by a displacement device. The lance has means for emitting a laser beam from a laser light source in the direction of the surface of the through opening. A preferably plate-shaped cover is provided, which is designed for placement on an end face of the component. The cover forms a passage opening which is dimensioned such that the lance can be moved through it. A compressed gas feed is integrated into the cover and comprises a connector for connecting to a compressed gas source and forms one or more outlet openings at the edge of the passage opening.