With the use of lasers, solid substrates can be converted directly into microplasmas. Solid targets are struck by high energy lasers, usually gas lasers, which are pulsed at time periods from picoseconds to femtoseconds (mode-locking). Successful experiments have used Ti:Sm, KrF, and YAG lasers, which can be applied to a variety of substrates such as lithium, germanium, plastics, and glass.[4][5]