Patent ID: 7847268
Filing Date: 2010-12-07
Classification: H01J

Abstract:
1. A charged particle detecting apparatus for detecting particles emitted from a sample, said particles comprising positive ions, negative ions and electrons, the detecting apparatus comprising: a housing, said housing defining a chamber in its interior, said chamber confined by conductive walls, said chamber having an opening to the outside of said housing; a grid for selectively attracting charged particles, wherein the grid is electrically biasable with respect to said housing, and wherein the grid is functionally aligned with said opening; a converter arrangement having at least one converter surface, said converter surface being electrically biasable with respect to the grid and with respect to the housing, wherein the converter surface is positioned with respect to the grid and the opening in such a way that charged particles attracted into the chamber by the grid impact on the converter surface; and an electron detector, wherein the electron detector is biasable with respect to the converter surface in such a way that electrons emitted from the converter surface are accelerated towards the electron detector and impact on the electron detector, wherein: said at least one converter surface has a concave shape, in order to provide an angle of impact of particles impacting on the converter surface depending on the point of impact.