Abstract: The present disclosure relates to a device for cleaning a surface in the interior of an optical system. The device includes a rod-shaped element. The rod-shaped element includes an imager configured to image contaminates on the surface, and a cleaner configured to remove contaminates from the surface. The device also includes a distance sensor that is configured to measure the distance between the surface and the end of the rod-shaped element. The device also includes a connection element configured to be secured at an opening of the optical system, and the connection element includes a guide element configured to guide the rod-shaped element.