Abstract: An electron microscope comprises an objective lens, at least an intermediate lens and a projector lens arrayed in this order on an optical axis. A movable aperture element is disposed between the objective lens and the intermediate lens whose disposition and magnetic excitation are so selected that electron beam diverging from a crossover produced at a back focal plane of the objective lens is focused on a plane of the movable aperture element. In the case of an electron microscope comprising an objective lens, an objective aperture element, a selected area aperture element, at least an intermediate lens and a projector lens arrayed in this order along an optical axis, an additional lens is disposed between the objective aperture element and the selected area aperture element. Disposition and magnetic excitation of the additional lens are so selected that electron beam diverging from a crossover produced at a back focal plane of the objective lens is focused at a plane of the selected area aperture element.

Abstract: A transmission electron microscope comprises an objective lens and a condenser lens which are so arranged that excitation of the condenser lens can be varied in association with variation in excitation of the objective lens. A cross-over point which is produced by the condenser lens of the last stage in the non-excited state of the objective lens is caused to coincide with a preselected position on the optical axis of the microscope, which position is determined in accordance with magnitude of excitation of the objective lens. The position of a convergence point of the electron beam produced downstream of a specimen to be observed is maintained substantially constant independently from variations in excitation of the objective lens. The direction in which the electron beam impinges on specimen at a point to be observed is maintained substantially constant independently from variation in excitation of the objective lens.

Abstract: An electron microscope of scanning type comprises first and second detectors for detecting secondary electrons emitted from a specimen irradiated by a scanning electron beam are disposed across the magnetic field of an objective lens of an electron-optical system of the microscope. The detection signals obtained from the outputs of both detectors are subjected to simultaneous signal processings.

Abstract: A symmetrical magnetic field type objective lens for an electron microscope comprises an upper magnetic pole piece and a lower magnetic pole piece disposed below the upper pole piece with a predetermined inter-pole distance S. Bores of a same diameter b are formed in the upper and the lower pole pieces, respectively. The distance S and the diameter are selected so that 1.ltoreq.S/b.ltoreq.5. Additionally, excitation J of the objective lens is so selected with respect to a predetermined magnetomotive force Jc.o. of a Riecke-Ruska's condenser objective lens that the condition that 1.4 Jc.o..ltoreq.J.ltoreq.1.7 Jc.o. is fulfilled. The objective lens assures a wide field of view without being accompanied with blurs or distortion of image.

Abstract: This invention relates to a method and apparatus for obtaining a single photograph of electron microscope images, with low gain in magnification, of relatively thick specimen, which photograph is suitable for direct comparison with a corresponding photograph of the same specimen obtained with an optical microscope: wherein either the specimen or the electron beam is so manipulated that the electron beam passes discretely and stepwisely through sequential portions of the specimen, and prior to impinging on the photographic plate the electron beam is screened to eliminate any portion thereof which would produce aberrations or other distortion and is controllably directed to impinge on a portion of the photographic plate which corresponds to the portion of the specimen through which the beam is passing.