It is well known that the pointing stability of a laser beam is decisive in determining the quality and efficiency of laser cutting, welding and drilling. Due to the instability of pointing for a long beam path which is increasingly used in material processing, there is a need for an automatic laser beam alignment system which is designed to accurately position laser beams to the working point of workstations. Such a system would require a device to automatically identify where the beam is. An instrument for doing this is described. The study presented here combines a rotating disk, having one slit, with a high speed optical sensor and a convergent lens to form a sensory unit to detect the laser beam position.