<p>A robotically operated laser seam stepper is configured with an elongated support column extending along a longitudinal axis and made from lightweight material. A support plate is displaceably mounted to the column while supporting thereon an optical head which is provided with optics. The optics is configured to direct a laser beam along a path towards a welding zone through a protective window of the optical head. The laser seam stepper further is structured with a first arm mounted to the support plate and extending along a longitudinal axis of the stepper diametrically opposite to the optical head. The inner surface of the displaceable arm defines a tunnel which is aligned with the optical head and axially traversed by the laser beam , a first axially flowing stream of pressurized gaseous medium , and by a second axially flowing stream of gaseous medium. The second stream entering the tunnel at a pressure lower than that one of the first stream in response to a pressure gradient generated in the column , does not generate vortexes within the column. The first and second streams exit through the downstream end of the tunnel next to the welding zone. As the streams flow out they carry out welding debris from the tunnel.</p>
