The Oxidative Tritium Decontamination System, OTDS, provides a method and apparatus for reduction of tritium surface contamination on various items. The reference design data has point groups having coordinates of points and obtained by dividing a progressive surface as a reference into a lattice form. At least one data acquisition device and the display device may be mounted on frames having a see-through display and an orientation sensor. A beam splitter is positioned between the laser and the terahertz generator to split off a probe laser beam from the terahertz inducing laser radiation which is also directed to the detector means.