Laser machining device warning of anomaly in external optical system before laser machining

A laser machining device configured to warn of an anomaly in an external optical system before laser machining, the laser machining device comprising:

• a laser oscillator;
• an external optical system configured to guide output light in a forward direction from the laser oscillator via a beam splitter to radiate the light to a surface of a workpiece;
• a reflective plate disposed perpendicular to an optical axis of emitting light emitting from the external optical system, the reflective plate having a constant reflectance to the emitting light;
• a return light measurement unit configured to measure intensity distribution of return light reflected off the reflective plate and returned to the external optical system via the beam splitter;
• a storage unit configured to store the intensity distribution of the return light in a normal state of the external optical system as reference data;
• a preprocessing unit configured to perform processing of identifying at least one of an optical axis shift, a beam diameter anomaly, a mode anomaly, a ghost, contamination of a protective window, and a focus shift due to thermal lens effect caused by the external optical system on a basis of comparison between measurement data of the intensity distribution of the return light and the reference data, before laser machining;
• and
• a warning unit configured to warn of an anomaly in the external optical system in accordance with the processing at the preprocessing unit.