Seam tracking with through-the-lens inline coherent imaging (ICI), following an 'S' shaped fillet weld over a convex part. The imaging beam makes transverse sweeps across the seam slightly ahead of the weld. The resulting 2D ICI images are automatically analyzed to identify the seam and provide real-time feedback to the motion control system. Here, we also make a second pass after welding to show the finished bead profile.