Patent ID: 7728274

Claim:
An imaging system comprising: an image intensifier configured to intensify a beam of radiation, the image intensifier including a negative electron affinity photocathode configured to produce a flux of photoelectrons when exposed to the beam of radiation, the beam of radiation including essentially radiations in a selected spectral band, the photocathode including a n+ doped semiconductor layer, one or more dielectric layers, an intrinsic semiconductor layer and a p+ doped semiconductor layer, the intrinsic semiconductor layer substantially thicker than the p+ doped layer such that substantially all of the photoelectrons are produced in the intrinsic layer; a current amplifier configured to amplify flux of photoelectrons; and a display system configured to display an image of a scene in the selected spectral band associated to the beam of radiation based on the amplified flux of electrons, wherein the one or more dielectric layers, the n+ doped semiconductor layer, the intrinsic semiconductor layer and the p+ doped semiconductor layer are constructed and arranged to form an optically coherent layer for the beam of radiation, and wherein the one or more dielectric layers are selected to reduce transmission of radiations in spectral bands outside the selected spectral band in the beam of radiation.