THIRD GENERATION PASSIVE VIEWERS

Because photo-emission has normally a cut-off wavelength of about 1.2 microns, to make use of the 1.6 micron emission from the night sky, a photoconductor material was used for the cathode material with a photoemitter deposited on the rear surface of the photoconductor. Others used solid state techniques principally based on gallium arsenide with the electrical output coupled to a electroluminescent display. The other method was the Quantum Counter using specially prepared crystals which emitted visible light when a local source of infra-red light was added to the infra-red emission from the scene.

Another night viewer was based on a solid state technique using Silicon or Germanium. The elemental detector was integrated with a high gain microminiature solid state amplifier. Versions were constructed with an electroluminescent display for imaging.