a single and dual lensed optical waveguide capable of approximating a desired iqp light profile to produce uniform welding with two overlapping gaussian light profiles that are mirror folded back on themselves . this allows for a resolution of the laser light that comes out of a fiber bundle in a weld width of under 1 / 100 , 000th of an inch . the results are narrow , uniform plastics ttir welds that show no signs of bubbling .