Time-resolved absorption spectroscopy in electron beam melting with blue vertical-cavity surface-emitting lasers

This paper addresses the challenge of understanding the dynamics of the interaction between partially evaporated metal and the liquid metal melt pool in electron beam melting (EBM), an additive manufacturing technology. Few contactless, time-resolved sensing strategies have been applied in this environment. We used tunable diode-laser absorption spectroscopy (TDLAS) to measure vanadium vapor in the EBM of a Ti-6Al-4V alloy at 20 kHz. Our study includes, to our knowledge, the first-time use of a blue GaN vertical cavity surface emitting laser (VCSEL) for spectroscopy. Our results reveal a plume that is roughly symmetrical with a uniform temperature. Moreover, we believe this work presents the first application of TDLAS for time-resolved thermometry of a minor alloying element in EBM.