Abstract: A transmission electron microscope having objective lens comprising upper, middle and lower magnetic pole pieces installed inside a yoke enveloping the first and second excitation coils. The polarity of the first magnetic field between the upper and middle magnetic pole piece is changed according to the selection of the two observation modes for an electron microscope image and for a converged beam diffraction pattern. However, the position of a specimen located at the midst of the second magnetic field between the middle and lower magnetic pole pieces is fixed during said two operation modes, so that analysis for a crystalline material of a very small area in the specimen is carried out by easy operation.

Abstract: In an electron microscope, having intermediate lenses between the object and the projection lenses, the first and second intermediate lenses are used for rotating the final electron microscope image without changes in magnification. The desired angle signal indicating to azimuth angle .theta. is designated by an operator. The absolute magnetomotive force .vertline.J1.vertline. and .vertline.J2.vertline. of the first and second intermediate lenses are controlled by a lens control means in the relation that (.vertline.J1.vertline.-.vertline.J2.vertline.) is proportional to the azimuth angle .theta. and (.vertline.J1.vertline.+.vertline.J2.vertline.) is nearly proportional to the square of the azimuth angle .theta..

Abstract: An electron lens equipped with a ferromagnetic body disposed in at least one of the pole gaps of the electron lens which serves as a switchable bypass for magnetic flux. The said ferromagnetic body is magnetically saturated under strong excitation, thereby permitting switching between the double-gap lens and the single-gap lens to be effected by changing the excitation current.

Abstract: An electron lens equipped with three magnetic pole pieces defining two gaps forming two magnetic fields of opposite polarities. The magnetomotive force of the magnetic field in the upper gap is fixed at a value close to the magnetomotive force providing a minimum focal length under the condition that the magnetomotive forces in both gaps are equal to each other, and a magnetomotive force of the magnetic field in the lower gap is larger than that of the magnetic field in the upper gap, so that not only radial and spiral distortions are eliminated but also the focal length is shortened.

Abstract: An electron lens equipped with three magnetic pole pieces defining two gaps forms two magnetic fields. The magnetic fields are generated in said gaps by opposite and same strength excitation. S1/S2 ratio is in the range of 2.7 to 3.8, in which S1 represents the first gap length between the upper and middle magnetic pole pieces and S2 represents the second gap between the middle and lower magnetic pole pieces, so that radial (isotropic) distortion is eliminated and spiral (anisotropic) distortion is extremely reduced.

Abstract: An electron lens equipped with three magnetic pole pieces defining two gaps forms two magnetic fields. The magnetic fields are generated in said gaps by opposite and same strength excitation. The bore diameters of the middle and lower magnetic pole pieces are equal and the bore diameter of the upper magnetic pole piece is 1.5 to 5 times larger than those of the middle and lower magnetic pole pieces, so that radial (isotropic) distortion is eliminated and spiral (anisotropic) distortion is extremely reduced.