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CHICKEN WIRE. An irregular pattern of dark thin lines in the field
of view either throughout the image area or in parts of the image
area. Under the worst-case condition, these lines will form hex-
agonal or square wave-shaped lines.
DARK (OR DARK AREA). A place in which there is very little light.
It docs not mean total darkness. Generally, this means conditions
similar to a quarter- moon or starlit night.
DEMIST SHIELDS. The two demisting shields are used to pre-
vent the eyepiece lenses from becoming fogged.
DIOPTER. A unit of measure used to define eye correction. Ad-
justments to the eyepiece focus ring will change diopter and pro-
vide a clearer image.
EDGE GLOW. There is a defect in the image area of the PVS-7.
Edge glow is a bright area (sometimes sparkling) in the outer por-
tion of the viewing area.
EMISSION POINT. A steady or fluctuating pinpoint of bright light
in the image area that does not go away when all light is blocked
from the objective lens. The position of an emission point within
the image area does not move. An emission point should not be
confused with a point light source in the distance.
FIXED-PATTERN NOISE. This is a cosmetic blemish in the im-
age area characterized by a faint hexagonal (honeycomb) pattern
throughout the viewing area that most often occurs at high light
levels or when viewing very bright lights. Fixed-pattern noise is in-
herent in the structure of the fiber optics and can be seen in every
image intensifier if the light level is high enough.
FLASHING. This is a defect in the image area of the PVS-7 . The
image appears to flicker or flash.
FLICKERING. See "flashing".
IMAGE-INTENSIFIER ASSEMBLY. An electro-optical device that
detects and amplifies ambient light to produce a visual image.
INFINITY FOCUS. Adjustment of the objective lens so that a dis-
tant object, such as a star or the point light on a distant tower,
forms the sharpest image
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