Online focus control sensor for laser welding offers improved reliability without process intrusion

A robust and non‐intrusive focus control system for laser welding has been developed under a collaboration between GSI Lumonics (Rugby) and Heriot‐Watt University in Edinburgh, as part of the Laser Engineering for Manufacturing Applications Programme (LEMA), funded by EPSRC. It uses the light generated by the process, together with the chromatic aberrations of the focusing optics to determine the focal position of the laser relative to the workpiece. Successful closed loop operation has been demonstrated over a wide range of welding conditions, including different materials and laser powers.