Final answer:
The conversion of light energy into electrons in an image intensifier is achieved by a photochathode, which is part of the photomultiplier tube that uses the photoelectric effect.
numbers of electrons is accomplished by a: photochathode
Step-by-step explanation:
In a conventional image intensifier, the conversion of light energy into proportional numbers of electrons is accomplished by a photochathode. This process is part of what occurs in a photomultiplier tube, where the photoelectric effect is harnessed.
Light from a scintillator strikes the photocathode, which emits electrons that are then multiplied at successive dynodes through a cascade effect. This results in an electrical signal that is proportional to the light's energy and can be used to construct an image.
A conventional image intensifier converts light energy into proportional numbers of electrons using a photomultiplier. This device is based on the photoelectric effect and consists of a series of dynodes that multiply the number of electrons.
When light enters the photomultiplier, it strikes a metal plate (photochathode) which ejects an electron. This electron is then attracted to the next plate, gaining enough energy to eject two or more electrons, and this process is repeated through the stages of the dynodes.