Two tubes (0.3mm wall thickness) are about to be butt welded over a 12mm coupler. 3D inline coherent imaging (ICI) reveals that the part is off-center in the fixture, moving in and out of focus as it rotates. The wobble is easily corrected by adjusting the fixture while watching the ICI video, and the position of the target seam can be confirmed. The ICI system can then be used to acquire a real-time depth profile of the weld as it’s being formed.