Evaluation of optical sensors for laser welding in a technical cognitive environment Available to Purchase

Focal spot positioning and robot path control require online measurement of the distance between a welding head and the workpiece to be processed. For autonomously working applications, such as cognitive focal shift control, distance measurements can be used to teach coaxial video images at different distances. This paper compares optical sensors based on laser triangulation with those based on optical coherence tomography, which can be embedded in either pre or post-process monitoring systems, thus allowing for accurate distance measurements. Because optical coherence tomography sensors are mainly used for medical purposes, their applicability in laser material processing was examined and verified. Using three workpieces with known geometrical properties, the lateral and depth resolution, and detectable angle dependency could be obtained. The advantages and limitations of the examined sensors are discussed here.