Patent ID: 8253100
Filing Date: 2012-08-28
Classification: H01J

Abstract:
1. An electron microscope comprising: an electron beam source for generating an accelerated electron beam; electromagnetic lenses for focusing the emitted beam; alignment coils for adjusting the optical axis of the beam transmitted through the lenses; a control unit for controlling an ambient pressure around a specimen; at least one vacuum pump mounted in a given location along an electron optical column; a gas inlet device mounted near the specimen; a plurality of orifices arranged inside the electron optical column and placed between the specimen and the electron beam source, each of said orifices being capable of changing its diameter; an imager for creating an image based on a signal arising from a region of the specimen illuminated with the electron beam; an image output device for recording and displaying the image; and a computer for controlling these components, the computer being programmed to find the orifices to be used and diameters of orifices capable of sustaining a pressure at which electrical discharge in the electron beam source does not occur from a gas species and a pressure around the specimen.