How to judge whether the image intensifier tube needs to be replaced

Image quality

Brightness reduction:

Under normal circumstances, the night vision device can provide a clear and bright image through the image intensifier tube, which is convenient for observing the target. When it is found that the image brightness is significantly reduced, even if the brightness knob is adjusted, it cannot be restored to the normal level, this may be a signal that the image intensifier tube performance has declined. For example, originally under certain moonlight conditions, the details of the target 100 meters away can be clearly seen, but now only a blurred outline can be seen, and the entire image is dark. This may be because the gain of the image intensifier tube is reduced, resulting in a weakened ability to amplify light, and replacement needs to be considered.

Resolution reduction:

Observing the clarity of the details of the image is an important basis for judgment. If you find that the texture, logo and other details of distant objects that were originally distinguishable have become blurred, such as when observing the signboard on a distant building, you could see the text clearly before, but now you can only see blurred blocks of color. This may be due to the resolution of the image intensifier tube. This may be caused by the aging of the internal microchannel plate or the photocathode. When the resolution drops to the point where it affects normal use, you should consider replacing it.

Increased noise:

Normal night vision images should be relatively clear and have fewer noise points. When a large number of snowflake-like noise points appear in the image, and these noise points seriously interfere with the observation of the target, it is likely that the signal-to-noise ratio of the image intensifier tube has decreased. For example, when used in a relatively dark environment, there were only a small amount of noise points that did not affect the observation before, but now the noise points cover the entire screen, making the target difficult to identify. This indicates that there may be a problem with the image intensifier tube and it is necessary to check whether it needs to be replaced.

Functional performance

Response time becomes longer:

When the image intensifier tube is working, it should be relatively fast from receiving the photon signal to outputting a clear image. If you find that it takes a long time for the night vision device to display a clear image after it is turned on, or the image adjustment is slow to respond when the light environment changes, this may be due to aging or failure of the electronic components inside the image intensifier tube. For example, when walking from indoors to outdoor dark environment, a normal image intensifier tube may adapt and display a clear image in a few seconds, while an aged intensifier tube may take more than ten seconds or even longer. In this case, you need to consider replacing it.

Reduced sensitivity to light changes:

A good image intensifier tube can make corresponding image adjustments according to slight changes in light. When it is found that even when there is a significant change in light (such as moonlight blocked by clouds or new artificial light sources), the image intensifier tube cannot effectively adjust the brightness and contrast of the image, and still presents a darker or too bright image, this may be due to a failure of its photocathode or electronic optical system, and it is necessary to evaluate whether to replace the image intensifier tube to restore normal function.

Physical damage

Appearance inspection:

Perform an appearance inspection on the image intensifier tube. If it is found that its outer shell has obvious signs of damage, such as cracks, deformation, etc., the internal components are likely to have been affected. For example, a cracked shell may cause dust and moisture to enter the interior, damaging key components such as the photocathode and microchannel plate. In this case, even if the image quality is not greatly affected temporarily, you should consider replacing the image intensifier tube to avoid further damage.

Signs of internal component failure:

If abnormal flickering, stripes or black spots occur during use, this may be due to a short circuit, open circuit or other failure of the electronic components inside the image intensifier tube. For example, if you see fixed black spots on the screen, it may be that a certain area of the photocathode is damaged and cannot generate photoelectrons normally. In this case, you generally need to replace the image intensifier tube to solve the problem.

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