Patent ID: 6570163
Filing Date: 2003-05-27
Classification: H01J

Abstract:
An electron detector having a principal axis and comprising:an accelerator plate for accelerating electrons emitted from a specimen, the plate having an aperture through which said electrons pass; a deflecting electrode arranged to deflect said electrons after passing through said aperture, by a process of secondary electron emission in response to said electrons impacting a deflecting surface of the deflecting electrode; and a collector disposed between said specimen and said deflecting electrode and arranged to collect electrons deflected by said deflecting electrode: wherein said deflecting surface of said deflecting electrode is inclined at an obtuse angle to said principal axis such that electrons emitted from the surface of the specimen travel outwardly from said principal axis and towards said deflecting surface to generate further secondary and tertiary electrons which in turn travel towards said collector, and the electron detector has rotational symmetry about said principal axis.