Phototube having domed mesh with non-uniform apertures

Claim 2

An electron discharge tube comprising an evacuated tube; a photocathode in said tube; a dynode having a covered input opening and an output opening in said tube; a dome-shaped radially symmetric mesh covering said input opening, said mesh having a plurality of spaced first elongated elements of electrically conducting material, and a plurality of spaced second elongated elements of electrically conducting material, said first elements and said second elements intersecting to form non-uniform apertures; said mesh further comprising a center and a periphery; said first elements being substantially radial elements; and said second elements being substantially circumferential elements; said apertures being progressively larger from the periphery to the center of said mesh whereby said central portion is more electron permeable than the peripheral portion.

Claim 3

The electron discharge tube of claim 1 wherein said non-planar mesh further includes an annular ring attached to said peripheral portion.

Claim 4

The electron discharge tube of claim 2 wherein said dynode is a cup dynode, comprising a cup shaped member having an approximate circular top opening; a circular flange around the periphery of said top opening; a side opening near the periphery of said top opening substantially perpendicular to said top opening; electron emissive material on the inside of said dynode; said dynode in said tube with said top opening facing said photocathode; and said dome-like mesh on said top opening with said central portion closer to said photocathode than said peripheral portion.

Claim 5

An electron discharge tube comprising an evacuated tube having therein: a photocathode; a cup-shaped dynode and an anode; a dome-shaped mesh in contact with said dynode, said mesh comprising a plurality of spaced elongated elements of electrically-conducting material, said first elements and said second elements intersecting to form openings of non-uniform size; said mesh being radially symmetric wherein said first elements are radial elements and said second elements are circumferential elements; said mesh further comprising a central portion and a peripheral portion; said mesh further comprising an annular ring attached to said peripheral portion; said dynode having an approximately circular top opening; a circular flange around the periphery of said top opening; a side opening near the periphery of said top opening substantially perpendicular to said top opening; electron emissive material on the inside of said dynode; said top opening facing said photocathode; said dome-shaped mesh being on said top opening with said central portion being closer to said photocathode than said peripheral portion; said evacuated tube including a faceplate and a tubular body with a portion of the body having a circular cross-section; said photocathode being on said faceplate; and said dynode located in the portion of the tubular body having the central cross-section, the flange of the dynode being substantially parallel to the plane of the circular cross-section and having a diameter substantially the same as the diameter of the circular cross-section; whereby said central portion is more electron permeable than said peripheral portion.

Claim 6

An electron discharge tube comprising an evacuated tube having therein: a photocathode; a cup-shaped dynode and an anode; a dome-shaped mesh in contact with said dynode, said mesh comprising a plurality of spaced elongated elements of electrically-conducting material, said first elements and said second elements intersecting to form openings of non-uniform size; said mesh being radially symmetric wherein said first elements are radial elements and said second elements are circumferential elements; said mesh further comprising a central portion and a peripheral portion; said mesh further comprising an annular ring attached to said peripheral portion; said dynode having an approximately circular top opening; a circular flange around the periphery of said top opening; a side opening near the periphery of said top opening substantially perpendicular to said top opening; electron emissive material on the inside of said dynode; said top opening facing said photocathode; said dome-shaped mesh being on said top opening with said central portion being closer to said photocathode than said peripheral portion; said evacuated tube including a faceplate and a tubular body with a portion of the body having a circular cross-section; said photocathode being on said faceplate; and said dynode located in the portion of the tubular body having the central cross-section, the flange of the dynode being substantially parallel to the plane of the circular cross-section and having a diameter substantially the same as the diameter of the circular cross-section; whereby said central portion is more electron permeable than said peripheral portion.

Claim 7

The electron discharge tube of claim 4 wherein said dynode includes a flat base and a side wall enclosing said base.

Claim 8

The electron discharge tube of claim 5 further including a box and grid dynode in said tube; said box and grid dynode having a curved surface; two side walls each attached perpendicularly to the curved surface; a planar grid attached to the curved surface and the two side walls; a bottom opening formed by the grid, the two side walls and the curved surface; and electron emissive material on the interior surface of the curved surface; and said box and grid dynode positioned with said grid substantially parallel and laterially adjacent to said side opening of said cup shaped dynode.

Claim 9

The electron discharge tube of claim 6 wherein said box and grid dynode is positioned between the flange of the cup shaped dynode and a plane of the base of the cup shaped dynode.

Claim 10

The electron discharge tube of claim 7 wherein said bottom opening lies in the plane of the base of the cup shaped dynode.

Claim 11

The electron discharge tube of claim 8 wherein said planar grid is less electron permeable near the curved surface than near the bottom opening.