An image intensifier is an electronic device in which gamma rays, X-rays, or ultraviolet waves from a source can be converted into a visible image or in which the
intensity of a visible image can be increased. The radiation falls onto
a special surface and releases electrons that are then accelerated and focused onto a CCD camera or fluorescent screen,
producing an enhanced visible image.
|This image intensifier consists of a scintillator
input window, a photocathode, electro-optics, a luminescent screen,
and an output window – all contained in an evacuated enclosure.
The X-rays strike the scintillating layer of the input screen, where
they are transformed into optically visible light rays. The emitted
photons hit a photocathode converting them to electrons. These electrons
are accelerated and focussed by means of electrical fields. The electrons
are then hurled against a phosphorus screen that changes the amplified
electrons back into visible light, creating a smaller, very bright
image against the output window. Behind the output screen, a digital
CCD camera captures the image on the output window for further image
processing purposes and display on a monitor. Image and caption: GE.