Process of making structured x-ray phosphor screen
AssigneeGeneral Electric Company
InventorsStanley J. Lubowski, Robert K. Swank
Life of this patent
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Abstract
A phosphor screen for converting x-rays to light includes a large number of discrete columns of the phosphor material, say doped CsI, with the spaces therebetween preferably filled with a reflective substance, which itself may be phosphor (e.g., Gd.sub.2 O.sub.2 S or La.sub.2 O.sub.2 S). Because of the resulting inhibition of lateral spread of light within the phosphor screen, it may be made thicker than conventional screens while achieving at least as high resolution and contrast, thereby increasing brightness (and thus requiring lower x-ray "doses"). A method for making the screen includes using a patterned substrate and wide-angle vapor deposition (as in a hot-wall evaporator) so as to deposit the phosphor only on the raised portions of the substrate.
Claims15
A method for making an improved phosphor screen of the type which absorbs one type of radiation and re-emits a different type of radiation, comprising the steps of:
- patterning a generally planar substrate so as to form a large plurality of relatively raised portions, each separated by a relatively recessed portion, throughout a substantial area of said substrate;
- vapor depositing a phosphor material on said patterned substrate at substantial angles relative to the normal to said substrate so that only said raised portions are covered by a substantial thickness of said phosphor material and said recessed portions receive substantially none, thereby yielding a phosphor layer comprising columns of phosphor material substantially separated from each other;
- and
- heat annealing said column-type phosphor screen so as to cause the phosphor material thereof to become substantially transparent by substantially eliminating any small bubbles which could otherwise cause radiation scattering within the material,
- whereby a phosphor screen including a series of spaced substantially transparent columns of the phosphor material is formed.
Dependencies are inferred from the claim text.