Editing Image intensifier (section)

==Operation==
[[File:Image intensifier diagram.png|thumb|upright=2.3|alt="Diagram of an image intensifier."|Photons from a low-light source enter the objective lens (on the left) and strike the photocathode (gray plate). The photocathode (which is negatively biased) releases electrons which are accelerated to the higher-voltage microchannel plate (red). Each electron causes multiple electrons to be released from the microchannel plate. The electrons are drawn to the higher-voltage phosphor screen (green). Electrons that strike the phosphor screen cause the phosphor to produce photons of light viewable through the eyepiece lenses.]]
Image intensifiers convert low levels of light [[photons]] into electrons, amplify those [[electron]]s, and then convert the electrons back into photons of light. Photons from a low-light source enter an objective lens which focuses an image into a [[photocathode]]. The photocathode releases electrons via the [[photoelectric effect]] as the incoming photons hit it. The electrons are accelerated through a high-voltage potential into a [[microchannel plate]] (MCP). Each high-energy electron that strikes the MCP causes the release of many electrons from the MCP in a process called [[Secondary emission|secondary cascaded emission]]. The [[microchannel plate|MCP]] is made up of thousands of tiny conductive channels, tilted at an angle away from normal to encourage more electron collisions and thus enhance the emission of secondary electrons in a controlled [[Electron avalanche]].

All the electrons move in a straight line due to the high-voltage difference across the plates, which preserves [[Collimated light|collimation]], and where one or two electrons entered, thousands may emerge. A separate (lower) charge differential accelerates the secondary electrons from the MCP until they hit a [[phosphor]] screen at the other end of the intensifier, which releases a photon for every electron. The image on the phosphor screen is focused by an [[Ocular lens|eyepiece lens]]. The amplification occurs at the microchannel plate stage via its secondary cascaded emission. The phosphor is usually green because the human eye is more sensitive to green than other colors and because historically the original material used to produce phosphor screens produced green light (hence the soldiers' nickname 'green TV' for image intensification devices).