Patent ID: 7186976
Filing Date: 2007-03-06
Classification: H01J

Abstract:
1. A reconfigurable scanning electron microscope comprising: an electron optical column and a sample chamber, said electron optical column comprising: an electron gun assembly, an electron optical system defining an optical axis and comprising a lens system which forms an electron probe from electrons emitted by said electron gun and a deflector which scans said electron probe across a sample, said lens systems comprising an objective lens comprising a gun side pole piece and a sample side pole piece, a carrier member which is arranged within a bore in said sample side pole piece, a first aperture bearing member and a second aperture bearing member, said first and second aperture bearing members being removably arranged within or at said carrier member so that said electron optical system can be operated with none, one or two aperture bearing members arranged in or at said carrier member, whereby said first aperture member is, in use, arranged within or at said carrier member so that its aperture is positioned on the optical axis and between the electron gun and said sample side pole piece, and said electron microscope further including a detector which is sensitive to emissions from a sample in response to scanned electron probe irradiation thereof.