Custom beam shaping for high-power fiber laser welding

With the ever increasing power and performance of fiber lasers, autogenous laser welding is becoming more practical for thick-section welding applications. High-power, high beam quality lasers can produce high aspect ratio welds at productive travel speeds with minimal distortion. However, autogenous laser welding can produce undercutting or other geometric stress concentrations at the weld toes. Through the design of custom optics, the laser beam can be directed to produce custom power distributions at the work, which can allow the fusion profile of the weld to be optimized for particular applications. By deflecting a portion of the laser power to trail the weld pool, the weld toes can be remelted to smooth stress concentrators and improve fatigue performance. This paper discusses the design and testing of custom zinc sulphide beam shaping optics coupled with a 10-kW IPG fiber laser.