Editing Image intensifier (section)

===Generation 2: micro-channel plate===
Second generation image intensifiers use the same multialkali photocathode that the first generation tubes used, however by using thicker layers of the same materials, the S25 photocathode was developed, which provides extended red response and reduced blue response, making it more suitable for military applications. It has a typical sensitivity of around 230 μA/lm and a higher quantum efficiency than S20 photocathode material. [[Redox|Oxidation]] of the cesium to cesium oxide in later versions improved the sensitivity in a similar way to third generation photocathodes. The same technology that produced the fiber optic bundles that allowed the creation of cascade tubes, allowed, with a slight change in manufacturing, the production of [[microchannel plate detector|micro-channel plate]]s, or MCPs. The micro-channel plate is a thin glass wafer with a [[Nichrome]] electrode on either side across which a large potential difference of up to 1,000 volts is applied.

The wafer is manufactured from many thousands of individual hollow glass fibers, aligned at a "bias" angle to the axis of the tube. The micro-channel plate fits between the photocathode and screen. Electrons that strike the side of the "micro-channel" as they pass through it elicit secondary electrons, which in turn elicit additional electrons as they too strike the walls, amplifying the signal. By using the MCP with a proximity focused tube, amplifications of up to 30,000 times with a single MCP layer were possible. By increasing the number of layers of MCP, additional amplification to well over 1,000,000 times could be achieved.

Inversion of Generation 2 devices was achieved through one of two different ways. The Inverter tube uses electrostatic inversion, in the same manner as the first generation tubes did, with a MCP included. Proximity focused second generation tubes could also be inverted by using a fiber bundle with a 180 degree twist in it.