Product Code: ICA10_503

Novel High-Speed Space-Resolved X-Ray System for In-Situ Diagnostics of Laser Based Processes
Authors:
Felix Abt, Ifsw, Institut Fur Strahlwerkzeuge; Stuttgart Germany
Rudolf Weber, Ifsw, Institut Fuer Strahlwerkzeuge; Stuttgart Germany
Thomas Graf, Ifsw, Institut Fuer Strahlwerkzeuge; Stuttgart Germany
Presented at ICALEO 2010

The comprehensive diagnostics of melt pool and keyhole dynamics is crucial in the ambitious efforts of understanding the complex behaviour of laser welding and cutting processes. A major drawback for the in-situ diagnostics of laser based processes is the fact that high-speed cameras and other optical sensors are only showing phenomena on the surface of the process.
Different approaches already exist to overcome this problem. Welding or cutting behind glass allows high frame rates for camera based diagnostics but does not show the actual melt inside the molten pool. Furthermore, due to the symmetry disturbance it is influencing the fluid dynamic by the glass window itself.
The use of radiographic systems that were first used in Japan in the 1990s is another approach to visualize the keyhole and melt pool dynamics of the real and uninfluenced process.
Actual high-brightness lasers allow very high process speeds and very small focal spot sizes. Hence they require corresponding fast and high resolution diagnostics systems.
This paper describes a novel high-speed x-ray diagnostics system. The micro focus imaging system allows both, high spatial and temporal resolution. Calibration images demonstrated detection of 0.25 mm feature size and smaller in steel. In combination with detection rates of over 5,000 Hz it enables outstanding new possibilities for direct observation of the keyhole and fluid dynamics.