Characterization of micron-sized particles in the focused laser beam during fiber laser keyhole welding

Abstract

In this study, the self-mixing interferometry (SMI) method was used for in situ measuring the micron-sized particles characterization in the focused fiber laser beam (FFLB) during the fiber laser keyhole welding. The micron-sized particles in the FFLB have a diameter of 0.655–6.55 μm and a velocity of 1–90 m/s, and particles with a larger diameter exhibited higher velocities. The share of particles with a diameter of 0.655–2 μm and that of particles with a velocity of 1–10 m/s decreased with the laser power, and increase with the detection height. The number, diameter and percentage of particles with higher velocities increased with the laser power and decreased with the detection height. These trends were due to particle vaporization induced by laser in the FFLB. In situ measurements characterization of particles was found instrumental in adjusting the laser power and detection positions.