A viewing system configured to combine multiple spectral images of a scene, the system includes a spectral beam separator configured to split an incoming beam of radiation into a first and a second beam of radiation, the first beam of radiation including radiations substantially in a first spectral band and the second beam of radiation including radiations substantially in a second spectral band; an image intensifier configured to intensify the second beam of radiation, the image intensifier including a photocathode configured to produce a flux of photoelectrons with substantially increased efficiency when exposed to the second beam of radiation, the photocathode constructed and arranged to substantially absorb all the radiations in the second beam of radiation; a current amplifier configured to amplify the flux of photoelectrons; and a display system configured to display an image of the scene in the second spectral band based on the amplified flux of electrons simultaneously with an image of the scene in the first spectral band.