Laser welding monitoring device and laser welding monitoring method

A laser welding monitoring device, comprising:

• a beam receiving unit configured to receive, when a material to be welded is irradiated with a laser beam emitted by a processing head provided to a laser welding machine, a radiated beam generated at an irradiation position of the laser beam and including a reflected beam of the laser beam and a monitoring beam, the monitoring beam being caused by thermal radiation and having a wavelength different from a wavelength of the reflected beam;
• a spectrometer unit configured to spectrally separate the reflected beam and the monitoring beam included in the radiated beam and convert the spectrally separated monitoring beam into a first electric signal;
• a trigger unit configured to convert the reflected beam into a second electric signal, to determine whether or not a level of the second electric signal is a predetermined threshold value or higher, and to immediately output a trigger signal indicating a timing at which the laser welding machine starts welding of the material to be welded when the level of the second electric signal is the predetermined threshold value or higher;
• and
• a laser welding monitor configured to start a determination of whether or not laser welding of the material to be welded is normally performed based on the first electric signal when the trigger signal is input.