US Patent 8378299 Twin beam charged particle column and method of operating thereof

A column for a charged particle beam device is described. The column includes a charged particle emitter for emitting a primary charged particle beam as one source of the primary charged particle beam; a biprism adapted for acting on the primary charged particle beam so that two virtual sources are generated; and a charged particle beam optics adapted to focus the charged particle beam simultaneously on two positions of a specimen corresponding to images of the two virtual sources.