Spot Vs. Blem: Night Vision Terms You Should Know

October 20, 2022
Spot Vs. Blem: Night Vision Terms You Should Know, Steele Industries Inc

Spot vs. blem? Spots and blems are terms commonly used when talking about an image intensifier tube. These terms are not interchangeable, as there is a clear difference between both.

Cosmetic Tube Imperfections with a Night Vision Device

Spot defects refer to the little black spots that could be present in an intensifier tube. These can be traced back to the manufacturing process.

Spots and the manufacturing process

Commonly, the spots occur from burns, debris, or broken light fibers during manufacturing. Blems have nothing to do with manufacturing and result from damaged tubes.

Industry Standards for Spots and Night Vision Blemishes

The frequency of spots in intensifier tubes has led to the creation of a spot spec. The spot spec sheet determines both the location and number of allowable spots in a single tube.

Since the spot specs vary by tube, there are allowances that coincide with a specific zone on the night vision device’s tubes. This is helpful to know when purchasing a night vision system.

Blems: prolonged exposure to a bright light source

Blems, short for blemishes, typically occur because of damage to the tube. Burn can happen when the tube is exposed to a bright light source for an extended period of time. If the burn is temporary, a ghost image appears and later resolves.

For temporary damage, it’s recommended that the device be left in operation within a light-sealed box.

In some cases, the tube’s micro channel plate will self-repair. Leaving it on in a zero-light room could also help with the repair.

Developing Huge Tube Blemishes

Night vision devices can also suffer damage when dropped. It’s possible that extremely bright pixels are the result of introducing light emission points, which is why many attempt the Hail Mary solution of blackboxing the unit.

You can also create blemishes on the left and right tubes by improper storage and transport. It could be possible to reset the system with multiple battery-draining cycles or by replacing the batteries.

In many cases, it’s best to have a night vision technician assess the damage and make repairs.

Understanding Dark Spot Terms for NV Tubes

When spots occur during manufacturing, there is little that can be done. However, blems are the result of damage or improper usage. Normal usage conditions won’t have cosmetic marks introduced.

Bright spots will be much more visible than the rest of the screen, and typically, bright spots disappear when there is no light with the ITT.

The most common terms for damaged tubes include the following:

  1. Burn-in: This is damage to an NV tube when exposed to bright light. It could be temporary or permanent scarring.
  2. Recoil damage: If the ITT experiences shock damage, such as being dropped, the components on the inside move around and become damaged.

Advice to Night Vision Users

Storing all the gear in a light-sealed case could help protect your NVD from developing a bright spot or other blemishes.

If the spots are faintly visible or barely noticeable, there is a chance the device will slowly repair itself.

It’s best to avoid all the blemish damage by taking care of your equipment.

Purchase Quality Equipment

Reduce the worry of blemishes when you purchase high-quality gear from Steele Industries. We carry NVDs for all your tactical and personal needs.