Abstract: An electron beam welding apparatus includes an electron beam generator for selectively emitting an electron beam into a weld chamber. The electron beam welding apparatus further includes a measuring device for detecting an intensity of the electron beam and a slit plate disposed between the electron beam generator and the measuring device. The slit plate permits passage of the electron beam through a slit formed in the slit plate, and the measuring device determines a location of the electron beam in dependence upon the detected intensity of the electron beam passing through the slit. The electron beam welding device further includes thermally non-conductive and/or absorbing materials strategically placed between parts to be welded and all components of mechanical assemblies requiring precision location.