Multiple-optics sensing of high-brightness disk laser welding process

• The multiple-optics sensing system has been established for monitoring laser welding.
• Visible light and laser reflection were detected by photodiode sensor.
• Features of keyhole and plasma were extracted from visual sensors.
• The relationships between sensing signals and welding status were confirmed.

A multiple-optics sensing system based on two photodiode sensors and two visual sensors has been established for monitoring a high-brightness disk laser welding process. By combining the high-speed photography and image processing technology, laser-induced metallic plasma and keyhole size were quantified to compare with the intensity of visible light and laser reflection which were detected by the photodiode sensors. Laser welding was carried out under different conditions. The results show that laser-induced metallic plasma is sensitive not only to the laser power, but also to the keyhole formation. Even the flowing rate of the shielding gas has an effect on the metallic plasma both on the top and at the bottom. Also, keyhole formation has a high impact on laser reflection. Both photodiode sensor and visual sensor show the same results. The proposed multiple-optics sensing system provided a better understanding and accurate evaluation on high-brightness disk laser welding.