Night Optics Falcon 6x Gen 3 Gated Long-Range Night Vision Binocular - Manual (Page 67)

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(4) Fixed-Pattern Noise. This is usually a cosmetic blemish
characterized by a faint hexagonal (honeycomb) pattern
throughout the viewing area that most often occurs at highlight
levels or when viewing very bright lights (see Figure 2-6). This
pattern can be seen in every image intensifier if the light level is
high enough. This condition is acceptable as long as the
pattern does not interfere with the operator's ability to view
the image or to perform the mission.
Figure 2-6. Fixed Pattern Noise.