Aluminized screen is a cathode-ray tube screen whose brightness is increased by coating the phosphor

Phosphor

A phosphor, most generally, is a substance that exhibits the phenomenon of luminescence. Somewhat confusingly, this includes both phosphorescent materials, which show a slow decay in brightness , and fluorescent materials, where the emission decay takes place over tens of nanoseconds...

 with a thin layer of aluminium

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

. Light from an excited part of the phosphor that would normally shine back inside the tube is thus reflected forward, increasing the total light output from the screen. The aluminium layer must be thick enough to reflect efficiently, but not so thick as to absorb too great a proportion of the electron

Electron

The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...

s that strike it.

Aluminized screen also refers to a projection screen that has an aluminum surface which reflects polarized light without altering its polarization. This is used for showing 3D movies where left and right images are shown with opposing polarization (e.g. vertical and horizontal, or right handed and left handed circular). Audience members wear polarized glasses to allow only the appropriate image to be seen by each eye.