Night vision device cosmetics – what can spoil the look of your IIT?

Night vision cosmetics refer to the looks of the Image Intensifier Tube (IIT) and are not tied to most of the parameters on the specifications of night vision devices. They are usually called blemishes by the community (in short: blem). Night vision blemishes can occur during manufacturing process, while using NVD incorrectly and may shorten the life cycle of IIT. 

Unfortunately, most blemishes cannot be fixed. They are there to stay. Below we will describe the most common blemishes.

Ott-Artur
Night vision fan, just like you

Spots

Most common form of blem is known as spots or blackspots. Blackspots can occur either during manufacturing of the IIT or due to incorrect use (for example laser damage).

Spots that occur during manufacturing can vary in size and their location determine the price and classification of the ITT. For example spots may determine if a tube falls under Photonis commercial or ECHO category. Location of spots in ITTs are divided between 3 zones. Different IIT classifications have standards on how many or big spots may occur in every zone.

Note: ECHO tube that has a blackspot due to incorrect use, is still in ECHO classification. It’s just damaged.

Spot can be spotted in zone 2 and 3 of this ITT

Burn in

Night vision burn in happens when a tube is exposed to bright light for a long period of time. Before IIT is burned permanently, it will experience a temporary burn. Temporary burn appears like a ghost image, traces that will disappear in a short period of time.
burn in ITT will experience temporary burn in which looks like traces that disappear in a short while. Tubes with P22 phosphor will experience temporary burn in more easily than other tubes.

Temporary burn-in

Permament burn-in

Fixed Pattern Noise (FPN)

Commonly referred to as chicken wire, will show up when the tube is really bright, be it due to bright environments or crazy signal to noise ratios on newer filmless tubes. It looks like chicken wire and is present in all tubes, just some tubes are more prone to showing it earlier due to good light amplification

Recoil damage

Recoil damage occurs when ITT experiences shock damage. Dropped from a height, or mounted on a gun. Technically speaking, this damage is due to the components inside the tube moving around. Only special NVDs are meant to withstand recoil, for example PVS-22.

Bright spots

Bright spots are tiny dots on tubes that will be visibly brighter than the rest of the screen. Bright spots will disappear when the ITT is presented with no light. If they won’t, then its an emission point.

Emission points

Emission points are bright spots that will not disappear after the ITT is presented with no light. This happens due to arcing between the photocathode and microchannel plate. Emission points can grow and render the tube useless.

ITT “going to air”

Going to air is termin used when ITT is losing vacuum. There is no way to fix the tube really after it has lost seal and the tube window will start fading away into a shadow. Best way to recognize a tube is its sloppy appearance, not a perfect circle

References

  • https://www.cloudynights.com/gallery/image/67303-image-intensifier-fixed-pattern-noise/
    (FPN)
  • https://www.thefirearmblog.com/blog/2021/09/03/night-vision-blemishes/ (blemishes)
  • https://youtu.be/fh69vM_mIhc?t=73 (bright spot)