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Idiomas disponibles
Idiomas disponibles
Generation 4
Conventional image intensifiers have a crystalline photo cathode with a thin film on the
micro-channel plate (MCP) to protect them from ion return. The tube built into this night
vision device does not need that coating. As a result, the service life is improved, and
the signal-to-noise (S/N) ratio increased by more than 20% as compared with
conventional tubes.
Due to the lacking thin film, this image intensifier has been
classified as fourth generation (filmless).
Halo
Appears as a circularly shaped, brightly lighting area in the tube image around a brightly
lighting object spot (e.g. the corona around a lantern).
Equivalent Brightness (EBI)
This is the minimum brightness required to perceive a luminance change in relation to
the basic brightness of the phosphor screen.
Wave length range and sensitivity
The diagram shows the photo cathode's course of sensitivity and, thus, also that of the
whole night vision device as long as no filters are used. In the wave length range from
450 to 850nm, the night vision device is most sensitive.
Radiant sensitivity
Wave length [nm]
Range of vision
This range measures the maximum distance to an object standardised by type, contrast,
shape, and size in which such object can be detected, allocated, recognised or identified
yet.
The range of vision depends on the ambient brightness. In a full moon night, luminance
equals 250mLux. In a cloudless night (new moon), luminance amounts to 1mLux,
whereas on a cloudy night sky (without extraneous lights) 0.1mLux are reached. For the
standardised information, a luminance of 1mLux is set forth in ISO14490-8 to determine
the range of vision. It needs to be determined at which distance a structure (black/white
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