Abstract: A phosphor screen which has an optical fiber plate formed of a number of bundled single optical fibers, each of which fibers consists essentially of a cylindrical core and a clad surrounding the curved peripheral wall of the core and a phosphor layer formed on one surface of the optical fiber plate, characterized in that the cylindrical core on the other surface of the optical fiber plate is removed, to provide a depression of a depth of at least 1 .mu.m, thereby producing an image having high contrast.

Abstract: A phosphor screen constructed by forming a phosphor layer on one side of an optical fiber plate consisting of a large number of bundled single optical fibers, each of which fibers comprises a cylindrical core and a clad surrounding the curved surface of the fiber core. At least that side of the respective fiber cores which faces the phosphor layer is removed, to provide a depression. Sufficiently large spaces are formed between the fiber cores and phosphor layer, to prevent both members from being brought into optical contact with each other.

Abstract: A phosphor screen which has an optical fiber plate formed of a number of bundled single optical fibers, each of which fibers consists essentially of a cylindrical core and a clad surrounding the curved peripheral wall of the core and a phosphor layer formed on one surface of the optical fiber plate, characterized in that the cylindrical core on the other surface of the optical fiber plate is removed, to provide a depression of a depth of at least 1 .mu.m, thereby producing an image having high contrast.

Abstract: An input phosphor screen includes a substrate having a substantially smooth surface, and first and second phosphor layers both vapor-deposited sequentially on the substrate. The first layer is made of phosphor crystal particles having a mean diameter of 15 .mu.m or less. The second layer has a thickness ten or more times that of the first layer and is made of individual columnar crystals of alkali halide grown vertically on the crystal particles, standing close together with fine spaces therebetween. A third layer is preferably deposited on the second layer as a continuous film. These three layers can be deposited by evaporating a phosphor material or materials at a prescribed temperature and at a predetermined degree of vacuum.

Abstract: An input screen and method of forming one for an image intensifier tube including a substrate in which a plurality of crystal grains of aluminum or aluminum alloy are formed in a plane with the crystal grains having non-directional shapes in the plane. The crystal grains are formed by heating in a vacuum or non-oxidizing atmosphere at a temperature between 450.degree. C. and 650.degree. C. The oxidized layer is next removed by an etchant, and a phosphor layer formed on the crystal grains by vapor-deposit.

Abstract: An input phosphor screen includes a substrate having a substantially smooth surface, and first and second phosphor layers both vapor-deposited sequentially on the substrate. The first layer is made of phosphor crystal particles having a mean diameter of 15 .mu.m or less. The second layer has a thickness ten or more times that of the first layer and is made of individual columnar crystals of alkali halide grown vertically on the crystal particles, standing close together with fine spaces therebetween. A third layer is preferably deposited on the second layer as a continuous film. These three layers can be deposited by evaporating a phosphor material or materials at a prescribed temperature and at a predetermined degree of vacuum.