aking NEA photocathode as the core component and utilizing the secondary electron multiplication effect of the micro-channel plate constitutes the basic features of the third-generation image intensifier. Due to the limitations of the gallium arsenide photocathode structure, the glass window at the incident end must be in the form of a flat plate, so the third-generation image intensifier can only take a double close-fitting structure. Its overall composition is shown in Figure 4-2b, which includes NEA Photocathode, microchannel plate, P20 phosphor screen, indium-sealed electrodes, and power supply.

 

High quantum efficiency and wide spectral response are the special advantages of this image intensifier. The actual measurement shows that the sensitivity of the transmissive arsenide photocathode is more than three times higher than that of the antimony potassium sodium cesium photocathode, and the service life is obviously prolonged. The quantum efficiency is also much higher. In these cases, its spectral response band is wide, and it extends to the long-wave region obviously, which makes it more effective to use the night sky radiation characteristics.

 

In addition to the above-mentioned binary III and V group element NEA photocathode such as GaAs:Cs₂0, there are also multiple (such as ternary, quaternary) III and V group photocathodes (such as indium gallium arsenic, indium arsenic phosphorus, etc.), which are Sensitive to infrared light, its long-wave threshold can be extended to 1.58~1.65um, which can make full use of the radiant energy of night sky light and improve the operating distance of the instrument; it can also be used with lasers working at 1.06μm wavelength to make active-passive The integrated night vision device makes the system develop in a multi-functional direction.

 

The third-generation image intensifier also has a micro-channel plate, so it also has the ability to automatically prevent strong light damage.