For every Night Vision device or related NV Goggles out in the current market today, it relies mostly to the Image Intensifier that comes with it.

Clarity, will depend heavily on the Generation of the Image Intensifier that allows image recognition, detection in the Dark.

An Image Intensifier is a vacuum tube that amplifies a low light-level scene to observable levels. The object lens collects light and focuses it onto the Image Intensifier. At the photocathode of the Image Intensifier the incoming light is converted into photo-electrons.

These photo-electrons are accelerated in an electric field and multiplied by a Micro Channel Plate (MCP).   An MCP is a very thin plate of conductive glass containing millions of small holes.

An electron entering a channel strikes the wall and creates additional electrons, which in turn create more electrons (secondary electrons), again and again. Subsequently the highly intensified photo-electrons strike the phosphor screen and a bright image is emitted that you can see.

• There are many different variables that can effect the distance that you can see with a Night Vision device. The larger the object the easier it is too see.
• The more ambient light you have (starlight, moonlight, infrared light) the better and further you will be able to see.
• One of the most important aspects to consider is the SNR (Signal-to-Noise), It is a measure of the light signal reaching the eye divided by the perceived noise as seen by the eye.
  • SNR determines the resolution at very low light-levels
  • Therefore, the higher the SNR the better the ability to resolve image details under low light-level conditions
  • SNR value is related to the specific design of the tubes
• Resolution is the maximum line density on a USAF target that can be resolved by a human eye and is expressed in line pairs per mm (lp/mm).
  • with High MTF (Resolution and Modulation Transfer Function) values at low spatial frequencies types tubes you get high image quality, sharp with good contrast like the XD-4™ tubes
  • generally, makes them more expensive

Generation 1

• electrostatically focused tubes
• high image resolution
• wide Dynamic range
• low noise

Generation 2

• micro channel plate for high gain
• resolution < Generation 1
• gain up to up to 30000 fL/fc

Generation 3

• GaAs photocathode
• resolution is higher than Generation 1
• enhanced sensitivity in the Near-Infrared

   

• The LifeTime of an Image Intensifier is very important, specially for Nigh Vision application
• For the XD-4™ Image Intensifiers of PHOTONIS the life time of 15,000 hours is the expected life time
• LifeTime; is defined as the time after which still 50 % of the original sensitivity is left.
• Identification range of an object in meters are as follows:
  • Gen 1 : 100m
  • Gen 1+: 200m
  • Gen 2 : 250m (clarity might not be that good)
  • Gen 2+: 300 to 500m (depending on tube class)
  • Gen 3 : 500m