In-process high power CO₂ laser beam position sensing

The case for in-process sensing is one of the strengths of laser materials processing, both in the variety of signals obtainable from the process and the range of techniques for beam guidance. It is known that beam/nozzle alignment is of importance for high quality laser cutting. Thus, an in-process beam position sensing system was devised in this study as one of the potential tools for automation of the cutting process. Further, if the beam could be stabilized at a given location automatically this would be equivalent to relocating the laser beam. Laser beam position sensing is the first step towards this goal. The aim of this study is to create a beam position sensing system. This work presents a new approach using a rotating slit, a focusing lens and a photodetector. An automatic alignment procedure is also investigated.