In this paper several approaches for the detection of the melt pool circle (i.e. its position and radius) in laser welding applications are described. Instead of indirectly examining the evolution of the melt pool via the radiation of plasma that is generated during the welding process, we use a direct view onto the melt pool that is possible in a narrow wavelength band with a coaxial aligned high speed CMOS imaging sensor. Since visual inspection is often a bottleneck in mass production, we focus on high speed approaches that enable real-time monitoring of the melt pool parameters
