Laser cutting machine and method for cutting workpieces of different thicknesses

A laser cutting machine for cutting a workpiece having a first thickness and a workpiece having a second thickness different from the first thickness, the laser cutting machine comprising:

• a laser source for producing an unprocessed laser beam having a laser wavelength of less than 4 μm;
• a compound fiber comprising a plurality of fibers;
• an adjustable optical deflection unit configured to selectively direct the unprocessed laser beam into one or more of the fibers of the compound fiber by a movement of the adjustable optical deflection unit, wherein a laser beam characteristic of a laser beam exiting the compound fiber differs depending upon which fibers of the compound fiber receive the unprocessed laser beam;
• and
• a control unit configured to control a movement of the adjustable optical deflection unit in accordance with a thickness of the workpiece to be cut,
• wherein the plurality of fibers of the compound fiber comprises a plurality of inner core fibers and at least one outer cladding fiber, and
• wherein the cladding fiber has an outer diameter which is greater than three times the largest fiber core diameter of the inner core fibers.

A laser cutting machine for cutting a workpiece having a first thickness and a workpiece having a second thickness different from the first thickness, the laser cutting machine comprising:

• a laser source for producing an unprocessed laser beam having a laser wavelength of less than 4 μm;
• a compound fiber comprising a plurality of fibers;
• an adjustable optical deflection unit configured to selectively direct the unprocessed laser beam into one or more of the fibers of the compound fiber by a movement of the adjustable optical deflection unit, wherein a laser beam characteristic of a laser beam exiting the compound fiber differs depending upon which fibers of the compound fiber receive the unprocessed laser beam;
• and
• a control unit configured to control a movement of the adjustable optical deflection unit in accordance with a thickness of the workpiece to be cut,
• wherein the plurality of fibers of the compound fiber have cross-sectional surface-areas and/or cross-section shapes of different sizes, and
• wherein the compound fiber comprises at least four individual fibers including two first individual fibers having cross-sectional surface-areas of the same size each with different cross-section shapes and two second individual fibers having cross-sectional surface-areas of the same size each with different cross-section shapes.

A method for cutting workpieces of different thicknesses, comprising:

• providing an unprocessed laser beam;
• in accordance with a thickness of the workpiece, selectively directing the unprocessed laser beam into one or more fibers of a compound optical fiber, comprising a plurality of parallel, non-concentric fibers, by movement of an adjustable optical deflection unit, wherein a laser beam characteristic of a processing laser beam exiting the compound fiber differs depending upon which fibers of the compound fiber receive the unprocessed laser beam, the laser beam characteristic of the processing laser beam differing depending on the thickness;
• and
• cutting the workpiece with the processing laser beam.