A diode image converter
was developed that produced a visible image from the photons invisible to the
human eye, emitted from a scene illuminated by an infra-red
source of light. A range of active night viewing
devices were developed based on this image converting device. Because the sources
used for flooding the scene with infra-red radiation were easily detected, the development
of passive viewing systems with a sensitivity to respond to the night sky radiation
was initiated. A starting point for this work was the demonstration in SRDE in 1956 that
the starlight energy reflected from the night scene was sufficient to create an electron
signal from a sensitive photoemissive cathode of high enough signal-to-noise ratio to
warrant the feasibility of eventually converting the signal to a visible output that could
be utilised by the human eye. Extensive studies of the radiation from the night sky were
carried out to quantify its temporal and spatial variations.
To aid the research and development programme a 100 metre long
dark tunnel was constructed at Steamer Point in which lighting could be controlled to
simulate various nightime illumination levels.
In addition to in-house studies, work was sponsored in industry,
where the considerable expertise of MULLARD LTD at their RESEARCH LABS. and RADIO VALVE
COMPANY proved invaluable for the production of prototype active and passive viewers for
evaluation and the subsequent manufacture of night viewing equipment that satisfied the
stated requirements of the military user.