Thomson-Csf

Jean-Pierre Galves

Jean-Marie Gutierrez

Henri Rougeot

Daniel Gibilini

A variable gain R.I.I. target is obtained by using an optical fibre board, whose face on the R.I.I. side has blind holes containing two types of granular luminescent materials having different luminous efficiencies and which are separated by a barrier layer. The electron beam from the R.I.I. photocathode is subject to two different accelerating voltages, the lower accelerating voltage exciting the luminescent material with the lower luminous efficiency and the higher accelerating voltage exciting the luminescent material with the higher luminous efficiency. Application to image intensifier tubes, used more specifically in radiology and fluoroscopy.

Image intensifier tube target and image intensifier tube with a video

In an X-ray image intensifier consisting of a scintillator screen associated with a photocathode, an electron-optical system and an output screen on which a strong visible image appears, resolution is improved by providing the scintillator screen, formed by a layer of cesium iodide doped with sodium deposited onto the substrate, a structure of needles approximately micrometers in diameter which are kept in the form of separate needles during the subsequent heat treatment by virtue of the presence of silicon oxide in the cesium iodide lattice.

X-Ray image intensifier

Process for producing a scintillator screen

The screen comprises superimposed layers of phosphor crystals having fluorescences of different colors separated by an inert layer having a substantially uniform thickness. In one example, the layers are of green phosphor P1 (J.E.D.E.C.) (.lambda.=550 nm) and red phosphor yttrium vanadate activated with europium (.lambda.=610 nm), in a proportion of 3 to 4 mg/cm.sup.2 and 0.15 mg/cm.sup.2 respectively. The inert layer is silicon sesquioxide (Si.sub.2 O.sub.3), and has a thickness of 1.2 .mu.m. High luminances are obtained throughout the range of colors, for operating voltages ranging between 10 kV and 17 kV.

Growing community of inventors

Paris, France

Jean-Pierre Galves