US 4,695,762 A · Electron beam pumped rod-like light emitters

Abstract

The luminescent screen of a cathode ray tube includes an array of monocrystalline or amorphous phosphor rod-like elements which are covered with a reflective coating except for one end of each element which serves as an output face. The phenomenon of the light trapping is advantageously exploited to achieve enhanced brightness. The screen is illuminated with an electron beam which has an essentially oblong cross section and which is oriented along the elongated dimension of the elements. In one embodiment the elements comprise epitaxial Lu.sub.3 Al.sub.3 Ga.sub.2 O.sub.12 :Ce on the top of a YAG substrate, and a light absorbing layer of Lu.sub.3 Al.sub.3.5 Fe.sub.1.5 O.sub.12 is formed on the bottom of the substrate. A printer utilizing such a CRT is described. Also described is a configuration in which each of the rod-like elements functions as a laser.

Claims18

Dependent claims

Optical apparatus comprising

means for generating a scannable electron beam, and
a luminescent screen including a transparent phosphor layer on which said electron beam is made incident to generate a scannable spot of light,
characterized in that
said phosphor layer comprises an array of elongated, rod-like elements each having at one end an output face from which said light emanates primarily in a direction parallel to the length of said elements,
a reflective coating covers other surfaces of each of said elements, and
said generating means provides said electron beam with an oblong cross section which is made incident along the length of selected ones of said elements.

3 more elements

Dependencies are inferred from the claim text.

Electron beam pumped rod-like light emitters

Life of this patent

Electron beam pumped rod-like light emitters

Life of this patent

Abstract

Claims18