Patent ID: 6841775
Filing Date: 2005-01-11
Classification: H01J

Abstract:
1. An electron microscope having an electron gun for producing an electron beam, the microscope being capable of being switched between (a) TEM imaging mode in which the electron beam is shot at a specimen by an illumination lens system, a TEM image of the specimen is formed out of electrons transmitted through the specimen by an imaging lens system, and the TEM image is made visible by observational means, and (b) scanning imaging mode in which the electron beam is focused onto the specimen by the illumination lens system, the beam is scanned across the specimen in two dimensions by deflection means mounted on a side of the specimen that faces the electron gun, resulting electrons from the specimen detected by at least one electron detector, and a scanned image of the specimen is displayed on a viewing screen of display means according to an output signal from the electron detector, said electron microscope comprising: astigmatic correction means for correcting astigmatism in the electron beam shot at the specimen; beam alignment means for aligning the electron beam shot at the specimen with respect to an optical axis; instruction means for commanding a Ronchigram display mode; and a control system which, when the Ronchigram display mode is commanded by the instruction means, controls the illumination lens system in such a way that the electron beam from the electron gun is focused onto the specimen, controls the deflection means such that the electron beam is stationarily directed at the specimen, and controls the imaging lens system such that a diffraction image on the optical axis which is created by electrons transmitted through the specimen creates a visible image on the observational means, wherein when commanding of the Ronchigram display mode is canceled, said control system maintains said lens conditions of said illumination lens system, controls said deflection means in such a way that the electron beam focused by said illumination lens system is scanned in two dimensions across the specimen, and switches the imaging mode to said scanning imaging mode.