Residual oxygen within the process atmosphere has a strong impact on the laser powder bed fusion process (PBF-LB/M) of titanium and especially influences the melt pool behaviour and spatter formation. PBF-LB/M using monosilane doped Ar shielding gas is a novel approach to achieve an oxygen-free atmosphere and prevent oxidation. For evaluating the benefits of this oxygen-free approach, the investigation of oxygen related effects on the melt pool are of particular interest. However, bright process emissions and high scanning speeds used in PBF-LB/M impede the camera-based process analysis. In this work, a narrow bandwidth laser illumination combined with a highspeed camera is implemented into an experimental laboratory PBF-LB/M machine to visualise the melt pool behaviour independent from process emissions. The image processing algorithms to extract geometrical features like melt pool size, shape, aspect ratio as well as the size and position of the keyhole are described. Furthermore, a method that enables the spatially resolved extraction of the molten metal’s oscillation frequencies is presented. This approach enables the correlation of melt pool dynamics with different process conditions. Baseline investigations showed a correlation between the process parameters and the melt pool oscillation. A change of the scanning speed from 100 mm/s to 200 mm/s with a laser power of 200 W leads to a shift of the primary oscillation frequency from 3.75 kHz to 6.1 kHz. Based on these results, the influence of residual oxygen on surface tension and viscosity as well as the resulting melt pool dynamics will be explored.