| 摘要 |
An apparatus for focusing a laser beam on a workpiece includes at least one transmissive optical element which is arranged at a tilting angle with respect to a plane perpendicular to a beam axis of the laser beam, the transmissive optical element comprising a first side and a second side through which the laser beam passes, a spatially-resolving detector configured to detect laser radiation reflected from the transmissive optical element, and an image evaluation device coupled to the detector, the image evaluation device configured to distinguish laser radiation reflected from the first side of the optical element from laser radiation reflected from the second side of the optical element. |
