X- and gamma-ray sensitive image intensification tube

[4. The image device of claim 1 wherein said sheet is a

• single crystal of cesium iodide.] 5. An image intensification tube responsive to stimulation by gamma energy or the like comprising:
• a. an evacuated envelope having an input end and an output phosphor spaced therefrom;
• b. a dish-shaped light-emissive layer near said input end and composed of a single crystalline sheet of photoluminescent material;
• c. an electron-emissive layer deposited near an inner surface of said light-emissive layer such that light photons emitted by said light-emissive layer stimulate said electron-emissive layer and cause the latter layer to emit electrons;
• d. means for accelerating electrons from said electron-emissive layer against said output phosphor;
• e. said dish shape of said light-emissive layer and said electron layer being substantially contoured to the shape of an accelerating electron field produced by said acceleration means so as to be focused therewith, and
• f. a mounting means supporting said light-emissive layer and
• electron-emissive layer near said input end. 6. The tube of claim 5 wherein said photoluminescent material is a single crystal of cesium
• iodide. 7. The tube of claim 5 wherein said photoluminescent material is a
• single crystal. 8. The tube of claim 5 wherein said photoluminescent
• material is cesium iodide. 9. The tube of claim 5 wherein said photoluminescent material is of sufficient thickness to absorb about 30 percent of source energy of 150 kev. or less and is transparent to its own
• light. 10. The tube of claim 5 wherein said photoluminescent material can withstand temperatures of 300.degree. F. without distortion or other
• degradation. 11. The tube of claim 5 wherein said mounting means is open at a central portion whereby entering energy passing through said central portion is not filtered or otherwise obstructed by said mounting means.
• The method of forming an input gamma ray sensitive structure for an image intensification tube comprising the steps of:
• a. heat softening a single crystal of cesium iodide;
• b. molding the single crystal of cesium iodide while heat softened to a dish-shaped configuration having a concave output surface to form a photoemissive layer;
• c. depositing an electron-emissive layer on the output dish of said formed dish-shaped cesium iodide crystal with the electron layer and crystal in sufficiently close juxtaposition that light energy emitted by the crystal stimulates said electron-emissive layer and causes the emission of electrons when in use;
• and
• d. securing a mounting means to the periphery of said photoemissive layer and mounting said layers in an envelope with the convex surface of the
• photoemissive layer oriented toward an input end of said envelope. 13. The method of claim 12 wherein the depositing steps is on a barrier layer and including the step of providing a barrier layer between the electron-emissive layer and the crystal.