| 摘要 |
According to one aspect of the invention for which protection is sought, there is provided an electron beam generator (100, 200) comprising: an electron source (104, 204) for generating a beam (120, 220) of electrons from an emission site of the source; means for accelerating the electrons; and focussing means for focussing the electrons onto a surface of a sample provided in an image plane, wherein the electron beam is arranged to pass through a plurality of apertures between the source and the image plane, each aperture having a diameter greater than that of the electron beam at the point at which the beam passes through the aperture, the generator being operable to image directly electrons from the emission site onto the image plane, the focussing means comprising a microscale lens (150, 250) comprising a lens element arranged to generate a magnetic field thereby to focus the electron beam onto the image plane, the lens element having a lens aperture therethrough through which in use electrons to be focussed are passed. |
