Universal coaxial process control system for laser materials processing

To achieve and maintain quality in laser materials processing it is recommended to employ a reliable process monitoring system. Today, quality monitoring systems for laser materials processing make use of different spatially sensors, experimental investigations have shown that the reliability of the monitored signals can significantly be increased by using a camera system with a two-dimensional spatial resolution instead of an integral detector. The improvement is achieved by exploiting the information provided by the spatially distributed intensity of electromagnetic radiation emitted by the process. In particular the coaxial set up of observation direction and laser beam axis allows an easy and reproducible installation. Based on these results an universal coaxial process control system was build up. The sensor of the System consists mainly of a high speed camera mounted on the housing of the focusing laser optic. The optical path of the camera is aligned with the laser beam path. The images taken from the process can be analysed on line. The System is adaptable to the laser materials process mainly by the image processing algorithm. It can be used for keyhole welding and welding of thin blanks. In case of cutting it is useful, also for monitoring of weak emitting materials like aluminium.