Metod och anordning för att övervaka status hos ett skyddsglas vid laserbearbetning

摘要

The invention relates to a method and an apparatus for checking the condition with respect to dirt contamination in the form of small smoke particles accumulated on a protective glass plate (3) arranged between the workpiece (2) and the laser optics (1) in a laser machining system and through which protective glass plate the machining laser beam (6) is arranged to pass. A thermal detector (10) is arranged, with a good thermal contact with the mechanical part attaching the protective glass plate in a holder (4), for sensing (measuring) the temperature of said mechanical attachment part. Due to an absorption of the laser beam by the small smoke particles an increased temperature is obtained on the protective glass plate and the mechanical parts that are attaching the protective glass in its holder (4). As soon as the detector signal has reached a certain level it can be indicated that it is time to replace the protective glass plate. The thermal detector (10) is preferably combined with an optical detector (8) sensing the radiation scattered by larger dirt particles collected on the protective glass plate during the machining process.