Abstract: A compact narrow band imaging system includes a vapor cell having a gas that receives and transmits light in accordance with the Faraday effect. A magnetic source is provided for applying a magnetic field to the vapor cell. Crossed polarizers are disposed before and after the vapor cell creating a Faraday optical filter. The only light that passes through the filter is light within a narrow band near the absorption peaks of the vapor. Other optical elements of the imaging system including filters, image detectors, electron multipliers, signal digitizers, and heat filters are co-located within the imaging system's common thermal isolation container to provide improved performance. The compact system is suitable for wide area surveillance, including daylight surveillance for combustion sources such as forest fires and missile exhaust.