Towards in-machine qualification of PBF-LB/M tracks with core/ring beam configurations using OCT

Laser powder bed fusion of metals (PBF-LB/M) is an established process whose industrial adoption remains limited by low productivity and continued need for defect mitigation. The use of beam shaping techniques may allow to increase the usable power levels and in-situ 3D surface topography monitoring could be employed to assess the right beam shape choice for different material and geometry combinations. Accordingly, this work presents the application of Optical Coherence Tomography (OCT) as an on-board measuring instrument along the adoption of ring and core intensity distributions at high power levels (up to 3 kW) to deposit single tracks. OCT measurements were benchmarked against cross section evaluations and focus variation microscopy acquisitions, showing that even with a relatively lower spatial resolution, OCT was also able to acquire key characteristics of the deposited material, namely deposited track width, height after the process, as well as the capillary depth during the process. Finally, powder depletion was assessed by combining pre- and post-process OCT acquisitions.