Apparatus for machining a workpiece with a laser beam coupled into a fluid jet, with automatic laser-nozzle alignment; method of aligning such a beam

An apparatus for machining a workpiece with a laser beam coupled into a water jet, the apparatus comprising

• a laser for providing the laser beam,
• a nozzle with an aperture for producing the water jet,
• one or more mirrors configured to provide the laser beam from the laser onto the nozzle, wherein at least one mirror is movable,
• a processor configured to control a movement of the at least one movable mirror to change a point of incidence of the laser beam on the nozzle, and
• a sensor configured to sense laser light reflected from a surface of the nozzle and produce a sensing signal based on the sensed reflected laser light,
• wherein the processor is configured to:
• control the movement of the at least one movable mirror to perform an automatic scan of at least a part of the surface of the nozzle with the laser beam,
• evaluate the sensing signal during the automatic scan,
• detect an appearance of a defined sensing pattern in the sensing signal evaluated during the automatic scan, and
• determine the laser beam being fully or partially aligned with the aperture of the nozzle based on the appearance of the defined sensing pattern.