| 摘要 |
To miniaturize a secondary-electron detector, a ring-shaped secondary-electron emissive material layer 44A is formed on a ring-shaped base 41 having a round hole 41a, via a ring-shaped insulating layer 42A and a ring-shaped high resistance layer 43A. Similarly, a ring-shaped secondary-electron emissive material layer 44B is formed on a ring-shaped base 33 having a round hole 33a, via a ring-shaped insulating layer 42B and a ring-shaped high resistance layer 43B. A arc-shaped multiplied-electron collecting electrode 461 is joined between the insulating layers 42A and 42B outside the secondary-electron emissive material layer 44B. A porous secondary-electron multiplication substance may be filled between opposed bases instead of the secondary-electron emissive material layers 44A and 44B, and an optical fiber coated with phosphor may be used instead of the electrode 461.
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