Four stage image intensifier, type 9694, c 1960s.
© Science Museum / Science & Society Picture Library
An image intensifier is a device used to amplify light and increase the brightnes of an image. A photocathode is used to convert photons into an image made up of electrons, which is then focused onto amplifying elements, increasing the electron intensity by as much as 50 times. The electron image is converted back into visible light by a fluorescent screen, reproducing the original picture, but with enhanced brightnes. Image intensifiers are used in night vision equipment for cinematography and by the military, as well as in astronomy. Made by EMI