Focusing structure for photomultiplier tubes
AssigneeRCA Corporation
InventorsRichard D. Faulkner, Robert E. McHose
Life of this patent
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Abstract
An electron discharge tube includes an evacuated envelope comprising a photocathode, an anode, a primary dynode and a secondary dynode for propagating and concatenating electron emission from the photocathode to the anode. A focusing electrode is disposed between the photocathode and the dynodes. The focusing electrode is capable of generating an electric field for focusing the electron emission between the photocathode and the primary dynode and also between the primary dynode and the secondary dynode. The focusing electrode has a planar surface that is reflective to light transmitted through the photocathode so that some of the transmitted light is returned to the photocathode to increase the responsivity of the tube.
Claims6
In an electron discharge tube comprising an evacuated envelope having therein, an electron emissive photocathode, a primary dynode having a substantially circular top opening for receiving electrons from said photocathode and an active area upon which substantially all of said electrons from said photocathodes impinge, thereby emitting secondary electrons therefrom, and a secondary dynode adjacent to said primary dynode for receiving said secondary electrons, the improvement comprising the combination of:
- an electrically conductive mesh adjacent to said primary dynode and covering said top opening of said primary dynode, and
- focusing means spaced from said mesh, said means being disposed between and electrically isolated from said photocathode and said dynodes for focusing electron emission between said photocathode and said active area of said primary dynode, and in conjunction with said photocathode, said primary dynode and said mesh, for focusing said secondary electrons between said primary dynode and said secondary dynode.
In an electron discharge tube comprising an evacuated envelope, an electron emissive photocathode, a teacup dynode having a substantially circular top opening for receiving electrons from said photocathode and an active area upon which substantially all of said electrons from said photocathode impinge, thereby emitting secondary electrons therefrom, a secondary dynode for receiving said secondary electrons, and an anode spaced from said secondary dynode, the improvement comprising the combination of:
- a dome-shaped radially symmetric dynode mesh covering said top opening of said teacup dynode, the apex of said dynode mesh being closer to said photocathode than is the peripheral portion of said dynode mesh, and
- focusing means spaced from said dynode mesh, said focusing means being disposed between said photocathode and said dynode for focusing electron emission between said photocathode and said active area of said teacup dynode, and in conjunction with said photocathode, said teacup dynode and said dynode mesh, for focusing said secondary electrons between said teacup dynode and said secondary dynode.
Dependencies are inferred from the claim text.