Important indicators of image intensifier tubes

The image intensifier tube is the core of the night vision device. Simply speaking, the principle of the image intensifier tube is to amplify the light.

 

 

It mainly consists of three parts "Photocathode", "Microchannel Plate (MCP)" and "Phosphor Screen".

 

The image intensifier tube receives photons through the "Photocathode", converts them into electrons, then amplifies the electrons through the "Microchannel Plate (MCP)", and finally "Phosphor Screen" and converts the amplified electrons back into photons, thus producing the image seen by the user.

 

 

So what are the important indicators of the image intensifier tube?

 

1.Figure of Merit (FOM)

FOM is an important indicator to help customers quickly distinguish whether IIT is excellent

“FOM” is equal to the product of central resolution and signal-to-noise ratio (SNR)

 

2.Signal-to-Noise Ratio (SNR)

Signal is the true light that is being picked up by the photocathode.

Noise is the scintillation that a tube puts off.

The signal-to-noise ratio determines the low-light resolution of a picture tube; therefore, a higher SNR will perform better in low-light conditions.

 

3.Resolution

Resolution is the ability of the image intensifier tube or night vision system to analyze the image, LP/MM (LINE PAIRS PER MILLIMETER) is the unit used to measure the resolution of the image intensifier. The higher the resolution, the sharper the image will look

 

4.Halo

A halo is a ring of light that forms around a concentrated bright light source. Halos are often prevalent in street lights and other similar concentrated light sources. The lower the halo value, the better

 

5.Equivalent Background Illumination (EBI)

Night vision EBI is the amount of light that is visible when the image intensifier tube is turned on but no light is shining on the photocathode. In order for an image to be visible through an image intensifier tube, the light hitting the photocathode must exceed the tube's natural background illumination, or the image will be washed out. This means that the EBI determines the minimum light level at which an image can be seen through the lamp. The lower the number of EBI, the better.

 

6. Autogating

Autogating is the process by which the tube power supply is continuously supplied and cut to the tube to help prevent glare damage and maintain optimal performance of night vision without blinding the user when exposed to a variety of bright light sources.

This process happens with incredible speed and is constantly working to deliver the best possible image through the tube. Not all tubes are automatically gated. This is a very important lamp feature that prolongs the life and performance of the lamp while preventing highlight damage.

 

7. Gain

Gain is the degree to which an intensifier is able to amplify a light source.

 

8. Manual gain

Manual Gain is a system feature that enables the user to manually control the brightness of the system. Manual gain units typically use image intensifier tubes of the 11769 or three wire type

 

9. ABC (Automatic Brightness Control)

Automatic brightness control is a function to automatically control the brightness of the lamp according to the environmental conditions.

Unlike manual gain image intensifier tubes, ABC tubes are protected from glare and automatically reduce the voltage of the microchannel plate to keep the brightness of the image intensifier within the optimal range and protect the tubes. Usually MX10160 type image intensifier tubes use automatic brightness control

 

10. Photocathode Sensitivity

Photocathode sensitivity is a measure of how well the photocathode in the image intensifier tube converts light energy into electrical energy. Photocathode sensitivity is measured in microamps per lumen (µA/lm)