Electron microscope having a compensation device for compensating the deviation of a diffraction image

Claim 2

In an electron microscope having in alignment in the following order along an electron beam path at least a source of electrons, an anode, a condenser lens, means for supporting a specimen, an objective lens, a field limiting aperture, an intermediate lens, a projection lens, and a fluorescent screen, a variable power source for supplying an exciting current to the intermediate lens, and means for varying the exciting current of the intermediate lens so as to selectively produce a microscope image and a diffraction image of the specimen on the fluorescent screen, the improvements which comprise: deflecting coils disposed between the objective lens and the intermediate lens for generating a composite magnetic field capable of compensating for any leakage magnetic field from the intermediate lens which causes diffraction image deviation; means connected to said power source for supplying exciting currents proportional to the exciting current of the intermediate lens to the deflecting coils; means for adjusting the amplitude of the exciting currents of the deflecting coils so as to vary the amplitude of the composite magnetic field; and means for changing the polarity of the exciting currents of the deflecting coils so as to change the direction of the composite magnetic field produced by the deflecting coils.

Claim 3

In an electron microscope having in alignment in the following order along an electron beam path at least a source of electrons, an anode, a condenser lens, means for supporting a specimen, an objective lens, a field limiting aperture, an intermediate lens, a projection lens, and a fluorescent screen, a variable power source for supplying an exciting current to the intermediate lens so as to selectively produce a microscope image and a diffraction image of the specimen on the fluorescent screen, the improvements which comprise: deflecting coils disposed between the objective lens and the intermediate lens for generating a composite magnetic field capable of compensating for any leakage magnetic field from the intermediate lens which causes diffraction image deviation; means connected to said power source for supplying an exciting current proportional to the exciting current of the intermediate lens to the deflecting coils; means for adjusting the amplitude of the exciting current of the deflecting coils so as to vary the amplitude of the composite magnetic field; and means for rotating the deflecting coils so as to change the direction of the composite magnetic field produced by the deflecting coils.

Claim 4

In an electron microscope having in alignment in the following order along an electron beam path at least a source of electrons, an anode, a condenser lens, means for supporting a specimen, an objective lens, a field limiting aperture, an intermediate lens, a projection lens, and a fluorescent screen, a variable power source for supplying an exciting current to the intermediate lens so as to selectively produce a microscope image and a diffraction image of the specimen on the fluorescent screen, the improvements which comprise: deflecting coils disposed between the objective lens and the intermediate lens for generating a composite magnetic field capable of compensating for any leakage magnetic field from the intermediate lens which causes diffraction image deviation; means connected to said power source for supplying an exciting current proportional to the exciting current of the intermediate lens to the deflecting coils; means for adjusting the amplitude of the exciting current of the deflecting coils so as to vary the amplitude of the composite magnetic field; and means for rotating the deflecting coils so as to change the direction of the composite magnetic field produced by the deflecting coils.

Claim 5

In an electron microscope having aligned in order at least a source of electrons, an anode for accelerating electrons from the source, a condenser lens, means for suPporting a specimen, an objective lens, a field limiting apertured electrode, an intermediate lens, a projection lens, and a fluorescent screen, a variable power source for supplying an exciting current to the intermediate lens, and means for varying the exciting current of the intermediate lens so as to selectively produce a microscope image and a diffraction image of the specimen on the fluorescent screen, the improvements which comprise: X-deflecting coils disposed between the objective lens and the intermediate lens for providing an X-direction deflection magnetic field; Y-deflecting coils disposed perpendicular to the X deflecting coils for providing a Y-direction deflection magnetic field; means connected to said power source for supplying exciting currents proportional to the exciting current of the intermediate lens to said X-and Y-deflecting coils so that the X-and Y-direction deflection magnetic fields of the X-and Y-deflection coils produce a composite magnetic field; and shifting means for shifting the composite magnetic field as desired over a range of 360* to thereby compensate any leakage magnetic field from the intermediate lens which causes diffraction image deviation.

Claim 6

In an electron microscope having aligned in order at least a source of electrons, an anode for accelerating electrons from the source, a condenser lens, means for suPporting a specimen, an objective lens, a field limiting apertured electrode, an intermediate lens, a projection lens, and a fluorescent screen, a variable power source for supplying an exciting current to the intermediate lens, and means for varying the exciting current of the intermediate lens so as to selectively produce a microscope image and a diffraction image of the specimen on the fluorescent screen, the improvements which comprise: X-deflecting coils disposed between the objective lens and the intermediate lens for providing an X-direction deflection magnetic field; Y-deflecting coils disposed perpendicular to the X deflecting coils for providing a Y-direction deflection magnetic field; means connected to said power source for supplying exciting currents proportional to the exciting current of the intermediate lens to said X-and Y-deflecting coils so that the X-and Y-direction deflection magnetic fields of the X-and Y-deflection coils produce a composite magnetic field; and shifting means for shifting the composite magnetic field as desired over a range of 360* to thereby compensate any leakage magnetic field from the intermediate lens which causes diffraction image deviation.

Claim 7

The combination defined in claim 3, which further comprises first adjusting means for adjusting the amplitude of the composite magnetic field,

Claim 8

The combination defined in claim 3, wherein said shifting means includes adjusting means for adjusting the amplitude of the respective exciting currents supplied to the respective X-and Y-deflecting coils and switching means for changing the polarity of the respective exciting currents so as to reverse the direction of the composite magnetic field.

Claim 9

The combination defined in claim 3, wherein either one of the X-and Y-deflecting coils are constructed mechanically to be rotatable over 360* and said shifting means includes rotating means for rotating the X-deflecting coils.

Claim 10

In an electron microscope having means for supporting a specimen, an electron beam generator for projecting to said specimen an electron beam, a field limiting apertured electrode, an objective lens disposed between said specimen supporting means and said apertured electrode, a fluorescent screen onto which an image of the specimen is projected, an intermediate lens disposed between said apertured electrode and said screen, a projection lens disposed between said intermediate lens and said screen, a variable power source for generating a variable exciting voltage, and coupling means for coupling said exciting voltage to said intermediate lens to cause an exciting current to flow through the intermediate lens, said coupling means operatingly varying the exciting current so as to selectively produce either of a microscope image and a diffraction image of the specimen on the screen, the improvement which comprises: a compensation lens disposed between the objective lens and the intermediate lens; means connected to said power source for supplying a compensation exciting current proportional to the exciting current of the intermediate lens to said compensation lens so that said compensation lens generates a compensative magnetic field between said objective lens and said intermediate lens; and adjusting means for varying the compensation exciting current to thereby compensate for a leakage magnetic field produced by said intermediate lens which causes diffraction image deviation with said compensation magnetic field.

Claim 11

In an electron microscope having means for supporting a specimen, an electron beam generator for projecting to said specimen an electron beam, a field limiting apertured electrode, an objective lens disposed between said specimen supporting means and said apertured electrode, a fluorescent screen onto which an image of the specimen is projected, an intermediate lens disposed between said apertured electrode and said screen, a projection lens disposed between said intermediate lens and said screen, a variable power source for generating a variable exciting voltage, and coupling means for coupling said exciting voltage to said intermediate lens to cause an exciting current to flow through the intermediate lens, said coupling means operatingly varying the exciting current so as to selectively produce either of a microscope image and a diffraction image of the specimen on the screen, the improvement which comprises: a compensation lens disposed between the objective lens and the intermediate lens; means connected to said power source for supplying a compensation exciting current proportional to the exciting current of the intermediate lens to said compensation lens so that said compensation lens generates a compensative magnetic field between said objective lens and said intermediate lens; and adjusting means for varying the compensation exciting current to thereby compensate for a leakage magnetic field produced by said intermediate lens which causes diffraction image deviation with said compensation magnetic field.

Claim 12

The combination defined in claim 7, wherein said compensation lens includes two pairs of deflection coils orthogonally arranged to each other at a position between said objective lens and said intermediate lens and supplied with the compensation exciting current respectively to provide a composite compensation magnetic field.

Claim 13

The combination defined in claim 8, wherein said adjusting means includes a first and a second adjusting means for varying the ampliTudes of the compensative exciting currents flowing through the respective pairs of the deflection coils, respectively.