Abstract: Apparatus for non-contact tracking of a weld seam to provide lateral position guidance of a welding torch advanced along the weld seam by a traveling carriage utilizes an electromagnetic radiation source for directing an unfocused beam onto the weld seam producing a spatial distribution of reflected electromagnetic radiation having an optical center of power the location of which is functionally related to the lateral position of the welding torch relative to the weld seam, and a lateral cell position sensor for sensing a shift in position of the optical center of power of the reflected electromagnetic radiation spatial distribution. Detection of a shift in position of the optical center of power is utilized as an indication of lateral deviation of the welding torch relative to the weld seam.The apparatus disclosed further includes signal processing circuitry that develops an electrical signal indicative of welding torch position for input to a torch drive servomechanism.