Origin of oscillations in optical signals for Nd:YAG laser welding Available to Purchase

Intense radiation is generated by the laser welding process over a broad range of wavelengths, from UV to IR. The core of the delivery optical fibre has previously been used to collect this light from which it is possible to detect various weld faults including focal errors and shield gas interruptions. We have designated this arrangement for the detection of process generated light as the core power monitor (PM). The detected light has a characteristic intensity modulation, postulated to be due to oscillations of the welding keyhole. In this paper, we describe imaging the welding process using a high speed camera, confirming the existence of keyhole oscillations and demonstrating that the light collected with the core PM is predominantly generated within the keyhole.