| 摘要 |
A pickup tube includes a generally cylindrical envelope having an input window at one end of the envelope and a radiation sensitive target adjacent to the input window. An electron gun is mounted in the other end of the envelope for generating an electron beam which is incident on the target. A mesh assembly is spaced from the target and in proximity therewith. The mesh assembly comprises a mesh electrode disposed between a mesh support ring and a novel mesh retaining ring. The novel mesh retaining ring has a mesh contact portion and a peripheral skirt portion which is disposed substantially orthogonally to the mesh contact portion. The skirt portion is directed toward the target for modifying the electrostatic field between the mesh electrode and the target so as to reduce beam landing error on the target and to prevent electrons, which are reflected from the target, from landing on the mesh retaining ring.
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