Multi-copy ion-valve radiography

Claim 2

Apparatus for providing a radiograph of an object differentially absorbing radiation from a radiation source, said apparatus comprising: an exposure chamber including a first electrode receiving the differentially-absorbed radiation; a second electrode spaced from said first electrode by a preselected distance; means filling the volume between said first and second electrodes for converting the differentially-absorbed radiation passing through said first electrode to electrically charged particles; a mesh structure positioned within the volume of converting means between said first and second electrodes, said mesh structure including a conductive mesh and a layer of insulative material supported upon the surface of the solid portion of said mesh closest to said first electrode; first means for providing an electric field between said first and second electrodes to cause at least some of the charged particles converted by said converting means to collect adjacent to the surface of said mesh structure insulative layer furthest from said mesh to form a charge pattern thereon representative of said object; a development chamber including a third electrode having a surface; a sheet of insulative material supported by said third electrode surface; means spaced from said third electrode surface for projecting a stream of ions toward the insulative sheet; and second means for forming an electric field between said ion projecting means and said third electrode for accelerating said ions towards said insulative sheet; means for moving said mesh structure from said exposure chamber, after collection of said charge pattern responsive to the differentially-absorbed radiation, to a position in said development chamber and between said third electrode surface and said ion projection means; and means for coupling at least said conductive mesh and said first and second electrodes to electrical ground potential during movement of said mesh structure; the flow of said projected ions through said mesh structure to the surface of said insulative sheet being controlled by the charge pattern deposited upon said mesh structure insulative layer to produce a charge pattern upon the surface of said insulative sheet representative of the radiation-absorbing properties of said object.

Claim 3

The apparatus of claim 1, wherein said converting means is a material in the gaseous state and maintained at a pressure greater than atmospheric pressure.

Claim 4

The apparatus of claim 2, wherein said gaseous material is one of Xenon, Krypton and Freon.

Claim 5

The apparatus of claim 2, wherein said exposure chamber further comprises means for maintaining said gaseous material at said pressure and within the volume between said first and second electrodes.

Claim 6

The apparatus of claim 4, further comprising means for selectively filling and emptying said volume with said gaseous material at said pressure.

Claim 7

The apparatus of claim 2 wherein said mesh has about 50% transmission with apertures having about 25 microns center-to-center spacing.

Claim 8

The apparatus of claim 6, wherein said insulative layer has a thickness of between about 3 microns and about 15 microns.

Claim 9

The apparatus of claim 1, wherein said converting means is a material in the liquid state.

Claim 10

The apparatus of claim 8, wherein the liquid material is tetra-methyl-tin.

Claim 11

The apparatus of claim 8, wherein said exposure chamber further comprises means for maintaining said liquid material within the volume between said first and second electrodes.

Claim 12

The apparatus of claim 10, further comprising means for selectively filling and emptying said volume with said liquid material.

Claim 13

The apparatus of claim 8, wherein said mesh has about 50% transmission, with apertures having about 40 microns center-to-center spacing.

Claim 14

The apparatus of claim 12, wherein said insulative layer has a thickness of between about 3 microns and about 40 microns.

Claim 15

The apparatus of claim 1, wherein the conductive mesh is a foraminate film of conductive material.

Claim 16

The apparatus of claim 1, further comprising means for depositing a substantially uniform background charge density upon said insulative layer surface prior to receipt of the differentially absorbed radiation.

Claim 17

The apparatus of claim 1, wherein said mesh has a resistivity less than about 10 9 ohms-centimeter.

Claim 18

The apparatus of claim 1, wherein said insulative layer has a resistivity greater than about 5×10 15 ohms-centimeter.

Claim 19

The apparatus of claim 1, wherein said first electrode is a planar conductive member.

Claim 20

The apparatus of claim 18, wherein said second electrode is a planar conductive member disposed parallel to the plane of said first electrode.

Claim 21

The apparatus of claim 19, wherein the distance between adjacent facing surfaces of said second electrode and the mesh of said mesh structure is between about 2 millimeters to about 4 millimeters.

Claim 22

The apparatus of claim 18, wherein said second electrode is adapted to provide, with said first electrode, an electric field converging within said exposure chamber toward said radiation source.

Claim 23

The apparatus as set forth in claim 21, wherein said second electrode includes a resistance member having a planar surface parallel to said first electrode and a curved surface opposite said planar surface and having a nonlinear resistance characteristic between a center line and the periphery thereof; and a conductive guard member disposed about the resistance member periphery; said first means including a source of electrical potential connected between the center of said resistance member curved surface and said guard member for forming concentric equipotential rings at said resistance member planar surface.

Claim 26

The method as set forth in claim 23, wherein step (c) comprises the step of: providing a quantity of a gaseous material within the exposure chamber for converting the radiation quanta into charged particles.

Claim 27

The method as set forth in claim 23, wherein step (c) comprises the step of: providing a quantity of a liquid material within the exposure chamber for converting the radiation quanta into charged particles.

Claim 28

The method as set forth in claim 23, wherein the layer of insulative material is supported upon a conductive mesh member having each a multiplicity of apertures therethrough in alignment with one of the multiplicity of apertures formed through the insulative material layer.

Claim 29

The method as set forth in claim 23, further comprising the step of depositing a substantially uniform background charge density upon the surface of the insulative material layer prior to receipt thereat of charged particles converted from the radiation quanta.

Claim 30

Apparatus for providing a radiograph of an object differentially absorbing radiation from a radiation source, said apparatus comprising: an exposure chamber including a planar conductive member forming a first electrode receiving the differentially-absorbed radiation; a second electrode spaced from said first electrode by a preselected distance and adapted to provide, with said first electrode, an electric field converging within said exposure chamber towards said radiation source; means filling the volume between said first and second electrodes for converting the differentially-absorbed radiation passing through said first electrode to electrically charged particles; a mesh structure positioned within the volume of converting means between said first and second electrodes, said mesh structure including a conductive mesh having a surface substantially in abutment with said first electrode, and a layer of insulative material supported upon the surface of the solid portion of said mesh closest to said first electrode; first means for providing an electric field between said first and second electrodes to cause at least some of the charged particles converted by said converting means to collect adjacent to the surface of said mesh structure insulative layer furthest from said mesh to form a charge pattern thereon representative of said object; a development chamber including a third electrode having a surface; a sheet of insulative material supported by said third electrode surface; means spaced from said third electrode surface for projecting a stream of ions toward the insulative sheet; and second means for forming an electric field between said ion projecting means and said third electrode for accelerating said ions towards said insulative sheet; and means for moving said mesh structure from said exposure chamber, after collection of said charge pattern responsive to the differentially-absorbed radiation, to a position in said development chamber and between said third electrode surface and said ion projection means; the flow of said projected ions through said mesh structure to the surface of said insulative sheet being controlled by the charge pattern deposited upon said mesh structure insulative layer to produce a charge pattern upon the surface of said insulative sheet representative of the radiation-absorbing properties of said object.

Claim 31

Apparatus for providing a radiograph of an object differentially absorbing radiation from a radiation source, said apparatus comprising: an exposure chamber including a planar conductive member forming a first electrode receiving the differentially-absorbed radiation; a second electrode spaced from said first electrode by a preselected distance and adapted to provide, with said first electrode, an electric field converging within said exposure chamber towards said radiation source; means filling the volume between said first and second electrodes for converting the differentially-absorbed radiation passing through said first electrode to electrically charged particles; a mesh structure positioned within the volume of converting means between said first and second electrodes, said mesh structure including a conductive mesh having a surface substantially in abutment with said first electrode, and a layer of insulative material supported upon the surface of the solid portion of said mesh closest to said first electrode; first means for providing an electric field between said first and second electrodes to cause at least some of the charged particles converted by said converting means to collect adjacent to the surface of said mesh structure insulative layer furthest from said mesh to form a charge pattern thereon representative of said object; a development chamber including a third electrode having a surface; a sheet of insulative material supported by said third electrode surface; means spaced from said third electrode surface for projecting a stream of ions toward the insulative sheet; and second means for forming an electric field between said ion projecting means and said third electrode for accelerating said ions towards said insulative sheet; and means for moving said mesh structure from said exposure chamber, after collection of said charge pattern responsive to the differentially-absorbed radiation, to a position in said development chamber and between said third electrode surface and said ion projection means; the flow of said projected ions through said mesh structure to the surface of said insulative sheet being controlled by the charge pattern deposited upon said mesh structure insulative layer to produce a charge pattern upon the surface of said insulative sheet representative of the radiation-absorbing properties of said object.