Monitoring of TIG welding using laser and diode illumination sources: A comparison study

This paper presents a vision system based on the use of a CMOS camera. The vision system has demonstrated its potential for applications of weld pool monitoring. It has been demonstrated in this study that the arc light can be successfully eliminated and that a substantial amount of information can be obtained in real time e.g. metal transfer in TIG welding and weld pool geometry, position and development. The system´s design and components are detailed in this study including camera technology and selection, and a range of illumination techniques. A study on the welding spectra has helped greatly in the selection of an optimum spectral window where arc radiations are low. A combination of optical filtering, short pulse laser illumination and fast-shuttering imaging techniques along with precise synchronisation and very accurate triggering methods has enabled high quality images of the weld area irrespective of the brightness of the intense arc light. A number of illumination sources including pulsed and continuous wave (CW) lasers, laser diodes and LED illumination are used.