US Patent 7119333 Ion detector for ion beam applications

Detection of weak ion currents scattered from a sample by an ion beam is improved by the use of a multiplier system in which a conversion electrode converts incident ions to a number of secondary electrons multiplied by a multiplication factor, the secondary electrons being attracted to an electron detector by an appropriate bias. In one version, the detector is a two stage system, in which the secondary electrons strike a scintillator that emits photons that are detected in a photon detector such as a photomultiplier or a CCD.