Method for Detecting Defects During a Laser-Machining Process and Laser-Machining Device

A method for detecting defects during a machining process, the method comprising:

• translating a plurality of workpieces or a laser beam relative to other so that the laser beam is incident on the plurality of workpieces along a predefined path, wherein the laser beam generates a weld seam or a cutting gap in the workpieces;
• detecting, in a two-dimensional spatially resolved detection field of a detector, radiation emitted and/or reflected by the plurality of workpieces as a result of the incident laser beam;
• selecting at least one detection field section in the detection field of the detector based on laser beam control data defining movement of the laser beam along the predefined path or based on position data of the laser beam along the predefined path, wherein each detection field section comprises a region encompassing less than the entire detection field;
• evaluating the radiation detected in in the selected detection field section;
• and
• determining whether a defect exists at the weld seam or the cutting gap based on the evaluated radiation.

A laser-machining device comprising:

• a machining head configured to provide a laser beam;
• a control unit for controlling the movement of the laser beam along a predefined welding or cutting path over a plurality of workpieces to be processed;
• a detector for detecting, in a two-dimensional spatially resolved detection field, radiation emitted by at least one of the workpieces;
• and
• an evaluation unit for evaluating the radiation detected in the detection field, wherein the control unit is configured to transmit to the evaluation unit control data for controlling the movement of the laser beam along the welding or cutting path, wherein the control data comprises position data of the laser beam relating to a previously determined actual position of the laser beam and/or a future position of the laser beam along the welding or cutting path, and
• wherein the evaluation unit is configured to:
• select at least one detection field section in the detection field based on the control data, wherein each detection field section comprises a region encompassing less than the entire detection field;
• evaluate the radiation detected in in the selected detection field section;
• and
• determine whether a defect exists at the weld seam or the cutting gap based on the evaluated radiation.