How does night vision work?

Night vision devices generally consist of an objective les, an eyepiece, a power supply and an image intensifier tube. This image intensifier tube, which has a photocathode tube within, is the core of the night vision scope. It consists of three components that work together to intensify any available light that enters it. The intensifier tube has, along with the photocathode tube, a part called a microchannel plate (MCP) and the phosphor screen, which renders the images for the eye. The photocathode senses light that the human eye may not detect in the darkness and converts the photons from the night sky in to electrons. The electrons exit the cathode, then enter and pass through the MCP. This small disk contains contains small fused fiber optics, think of them as 10 million small tubes or channels that amplify light. The electrons move through this thin disk bouncing of the channel, more electrons are released. The electrons exit the MCP and strike a phosphor screen, similar to the ones used in tube television sets. The multiplied electrons produce photons when they hit that phosphor screen producing a green glow. The pattern produced is the image pattern that originally entered the MCP only now, the small amount of light has been increased so that the user can see what is happening in the dark translated on screen.