Product Code: ICAL09_1910

FOCAL SHIFT MONITORING AND COGNITIVE CLOSED-LOOP CONTROL BY ANALYSIS OF CO-AXIAL VIDEO DATA
Authors:
Thibault Bautze, LDV, Technical Univ. of Munich; Munich Germany
Tobias Kaiser, FSR, Technical Univ. of Darmstadt; - Germany
Sonja Huber, IWB, Technical Univ. of Munich; Munich Germany
Presented at ICALEO 2009

Most laser welding heads offer the ability to connect a co-axial camera, using the same focusing lenses as the laser beam. Thus, the focal shift induced by heating the lenses and thus influencing the laser beam, alters the video data acquired. In the proposed approach, the sharpness of the video data is used to monitor the focal shift and distance changes relative to the workpiece surface. Distance control is achieved by means of a controllable z-axis. The addition of an Artificial Neural Network allows the correction of uncompensated errors such as shifts caused by the collimating optics. As a result, the process errors caused by thermal lensing can be reduced, improving the process quality and other sensor data acquisitions.