An atom probe using a picosecond or femtosecond laser

摘要

An atom probe, preferably a three-dimensional atom probe, comprising a picosecond or femtosecond laser to evaporate ions from the surface of a sample under investigation. Use of such a laser allows atom-probe techniques to be applied to materials which are not highly conducting, while reducing both surface and bulk heating of the sample. An optics system is also provided to focus the laser to a spot size of approximately 50 microns. The atom probe also comprises a reflectron having improved space-angle focussing over a wide range of entry angles (up to 45{) and configured to substantially eliminate chromatic aberration. The reflectron comprises a front electrode, a back electrode, and a plurality of intermediate electrodes, at least one of the front and back electrodes being capable of generating a curved electric field substantially equivalent to the electric field produced by a point charge.