Optical sensing technique for Nd:YAG laser welding process monitoring, using light returned through the cladding of the delivery fibre optic

摘要

A non-intrusive optical sensing technique for Nd:YAG laser welding monitoring is described. The Cladding Power Monitor (CPM) monitors the light returned through the cladding of the delivery fibre optic, and appropriate optical filtering isolates the light radiated from the plume of hot gas which forms above the weld. The successful detection of welding faults using this optical signal is described, including laser focus errors and shield gas interruption.