| 摘要 |
In electron beam apparatus, in which a finely focused probe is caused to impinge on the surface of a specimen and the resulting secondary electrons are collected and used to show potential distribution on the specimen surface the detector includes, between the collector and the specimen, a positive grid and a further grid, this further grid being of variable low or negative potential to form effectively a potential barrier of adjustable height to discriminate between electrons coming from regions of different potential. |
