Image intensifier tube having a multi-radius photocathode

Claim 2

A photocathode having an aspherically curved, effective electron emitting surface comprising a concave central portion and an encircling marginal portion adjacent its periphery, the marginal portion having a radius of curvature greater in magnitude than the radius of curvature of the central portion and the entire electron emitting surface including both of said portions being effective in the formation of an electron image in response to an incident radiational image.

Claim 3

A photocathode as set forth in claim 1 wherein the marginal portion has a radius of curvature which extends in the same direction as the radius of curvature of the central portion.

Claim 4

A photocathode as set forth in claim 1 wherein the marginal portion has a radius of curvature which extends in the opposite direction as compared to the radius of curvature of the central portion.

Claim 5

A photocathode as set forth in claim 2 wherein the effective electron emitting surface comprises a hyperbolic surface of revolution.

Claim 6

An image intensifier tube comprising: an evacuated envelope having an input faceplate and an output faceplate; an aspherically curved photocathode disposed within the envelope adjacent the input faceplate; said photocathode including an effective electron emitting surface having a concave central portion and an encircling marginal portion adjacent its periphery; said marginal portion having a radius of curvature greater in magnitude than the radius of curvature of said central portion and the entire electron emitting surface including both of said portions being effective in the formation of an electron image in response to an incident radiational image; and a substantially flat imaging screen disposed within the envelope adjacent the output faceplate and axially aligned therewith.

Claim 7

An image intensifier tube comprising: an evacuated envelope having an input faceplate and an output faceplate; an aspherically curved photocathode disposed within the envelope adjacent the input faceplate; said photocathode including an effective electron emitting surface having a concave central portion and an encircling marginal portion adjacent its periphery; said marginal portion having a radius of curvature greater in magnitude than the radius of curvature of said central portion and the entire electron emitting surface including both of said portions being effective in the formation of an electron image in response to an incident radiational image; and a substantially flat imaging screen disposed within the envelope adjacent the output faceplate and axially aligned therewith.

Claim 8

An image intensifier tube as set forth in claim 5 wherein a layer of fluorescent material is coaxially disposed between the input faceplate and the photocathode.

Claim 9

An image intensifier tube as set forth in claim 5 wherein an anode sleeve is coaxially disposed between the photocathode and the imaging screen and is axially spaced from the photocathode.

Claim 10

An image intensifier tube as set forth in claim 7 wherein a tubular focusing electrode is coaxially disposed between the photocathode and the anode sleeve and axially spaced therefrom.

Claim 11

An image intensifier tube comprising: a tubular envelope having an input faceplate at oNe end and an output faceplate at the other end, the input faceplate having an aspherically curved inner surface including a concave central portion, a contiguous intermediate annular portion and a successively contiguous encircling marginal portion adjacent its periphery, the intermediate and marginal portions having respective radii of curvatures greater in magnitude than the radius of curvature of the central portion; a conforming layer of photoemissive material on the inner surface of the input faceplate, the entire photoemissive layer including the concave central portion, the intermediate annular portion and the encircling marginal portion adjacent its periphery being effective in the formation of an electron image in response to an incident radiational image; an anode sleeve disposed within the envelope in spaced coaxial relationship with the photoemissive layer; and a substantially flat imaging screen disposed within the envelope in spaced coaxial relationship with the anode sleeve and located adjacent said output faceplate.

Claim 12

An image intensifier tube comprising: a tubular envelope having an input faceplate at oNe end and an output faceplate at the other end, the input faceplate having an aspherically curved inner surface including a concave central portion, a contiguous intermediate annular portion and a successively contiguous encircling marginal portion adjacent its periphery, the intermediate and marginal portions having respective radii of curvatures greater in magnitude than the radius of curvature of the central portion; a conforming layer of photoemissive material on the inner surface of the input faceplate, the entire photoemissive layer including the concave central portion, the intermediate annular portion and the encircling marginal portion adjacent its periphery being effective in the formation of an electron image in response to an incident radiational image; an anode sleeve disposed within the envelope in spaced coaxial relationship with the photoemissive layer; and a substantially flat imaging screen disposed within the envelope in spaced coaxial relationship with the anode sleeve and located adjacent said output faceplate.