Patent ID: 6462324
Filing Date: 2002-10-08
Classification: H01J

Abstract:
A photomultiplier tube comprising:an envelope having a faceplate; a photocathode disposed in said envelope for receiving radiant energy incident on the faceplate of said envelope and providing photoelectrons in response thereto; a first dynode disposed in said envelope having an input aperture facing said photocathode, an output aperture, and a secondary emissive surface formed between said input and output apertures, said secondary emissive surface being oriented for receiving photoelectrons from said photocathode; and a field isolating mesh disposed over the input aperture of said first dynode, said field isolating mesh including a) a periphery formed of an electrically conductive material for providing an isolating electric field in the vicinity of the input aperture of said first dynode, when energized, and b) a central opening that is dimensioned to provide a maximum unobstructed path from said photocathode to the secondary emissive surface of said first dynode, and said field isolating mesh having at least a first portion thereof in physical contact with said first dynode such that said first portion of said field isolating mesh is at the same electrical potential as said first dynode when energized.