Night vision goggles boost a dim, dark scene in a series of simple steps:
1. Dim light from a night scene enters the lens at the front. The light is made of photons (particles of light) of all colors.
2. As the photons enter the goggles, they strike a light-sensitive surface called a photocathode. It’s a bit like a very precise solar panel: it’s job is to convert photons into electrons (the tiny, subatomic particles that carry electricity round a circuit).
3. The electrons are amplified by a photomultiplier, a kind of photoelectric cell. Each electron entering the photomultiplier results in many more electrons leaving it.
4. The electrons leaving the photomultiplier hit a phosphor screen, similar to the screen in an old-fashioned television. As the electrons hit the phosphor, they create tiny flashes of light.
5. Since there are many more photons than originally entered the goggles, the screen makes a much brighter version of the original scene.
