Enclosure (2) to COMDTINST 1543.3
For this reason, the apparent brightness of a light should not be used as an estimate for distance
to that light.
Older generations of night vision were plagued with what was known as "blooming"
problems. This "blooming" was the actual whiting out of the night vision image caused by a
bright light source in the field of view. With modern Generation 3 night vision devices, this
blooming has been almost entirely eliminated. What you will now see around a bright light
source is a halo, which may obscure the area around the light source. Reducing brightness on
variable gain equipped units may reduce the halo.
Image intensification night vision will not work in the total absence of light, at the bottom of a
cave, for instance. As we now know, this light does not have to be light in the visible
wavelength, but there must be some source of light or photons for the night vision to function
correctly. Remember that night light is reduced by passing cloud cover and while operating
under trees or in building shadows and the equipment is less effective when viewing into
shadows and other darkened areas. Scintillation is a faint, random, sparkling effect throughout
the image area. Scintillation is more pronounced under low-light conditions. Seeing it is an
indicator that you need to consider using supplemental illumination.
Contrast reversal is a characteristic of night vision that must be considered from a tactical
standpoint. Night vision devices are very sensitive to reflected IR light. Objects that reflect IR
light will appear light, while objects that absorb IR light will appear in dark - regardless of
what color they actually are. A shiny, black automobile that's just been waxed, for example,
might look light-colored through a night vision device because it is actively reflecting IR light
from the night sky.
Clothing may also appear different through night vision than it does during the day, again
based on whether it reflects or absorbs light. If you're not careful, this could cause you to
provide an inaccurate description of a suspect. Or, imagine being in an operational
environment where the bad guys have night vision equipment. You are trying to take
advantage of the darkness, shadows, or perhaps even a tree line or other dark hide. If your
uniform and tactical equipment were to reflect near-infrared light, you could end up giving
yourself away by not blending into your background. In most cases, the BDU-type uniforms
designed for the military and police are specifically made to absorb light and stay dark under
night vision conditions. However, this may not be true with all the accessories and tactical
equipment worn with and over the BDUs. Conversely, there may be some conditions where
you want your uniform and equipment to actually reflect near-infrared light so as to better
blend in to this environment. Examples include snow and desert conditions. The only way to
ensure that your uniform and equipment won't give you away under night vision conditions is
to go out at night and look at them with night vision equipment.
Two other phenomena exist with night vision with which the user should be aware; black spots
and chicken wire. Black spots are cosmetic blemishes
in the image intensifier or can be dirt or debris between the
lenses. Black spots that are in the image intensifier do not
affect the performance or reliability of a night vision device
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