Simultaneous 3D tracking and temperature measurements of L-PBF spatter particles using a single camera

Abstract

This work discusses the implementation of a novel technique for simultaneous 3D particle tracking velocimetry and dual-wavelength pyrometry of spatter particles ejected during the Laser-Powder Bed Fusion (L-PBF) process using a single high-speed spectral plenoptic camera. In this methodology, particle tracking uses the Light-Field Ray Bundling algorithm paired with a four-frame best estimate track initiation with 3D Kalman filter for tracking to generate high-resolution, time-resolved 3D tracks of spatter particles. Utilizing the same light-field image data, spatter particle temperature is measured using dual-wavelength pyrometry that calculates temperature from the ratio of two narrow-band wavelength intensities. Preliminary results demonstrate the viability and potential of this technique for the L-PBF processes on the example of a turnaround laser scan. The temperature measurements indicate that the detected particles are in the liquid phase, with temperatures greater than 1950 $\text{°}$C. The simultaneous measurements demonstrate an overall deceleration and cooling of particles during their flight.