Apparatus for X-ray radiography

Claim 1

Apparatus for X-ray radiography, comprising: a first electrode adapted to transmit a pattern of differentially-absorbed X-ray radiation; a second electrode spaced from, and parallel to, said first electrode; a sheet of insulative material adjacent a surface of said second electrode facing said first electrode; a structured photocathode fabricated of X-ray photoemissive material directly upon a surface of said first electrode facing said second electrode, said structured photocathode comprising a two-dimensional array of substantially parallel rods of a non-photocathodic material with each rod disposed substantially perpendicular to said first electrode surface and extending a portion of the distance toward said second electrode; and a layer of photocathodic material fabricated around each rod substantially along the entire length thereof; an avalanche-amplifying gas filling the gap between said insulative sheet and said first electrode and surrounding the array of substantially parallel rods of the structured photocathode; and means for forming an electric field between said first and second electrode; the photoemissive material surrounding said array of rods emitting, responsive to said X-ray radiation, charged particles from the entire surface of the photocathodic material layers thereof, said charge particles interacting with said gas and said field, respectively, for amplification and subsequent collection at said sheet.