JPH0896737A - electronic microscope - Google Patents

Abstract

(57) [Summary] [Structure] Magnetic field applying means 7 provided in the objective lens 5, electron beam deflection correcting means provided between the objective lens 5 and the imaging lens 9, and an arbitrary phase of the alternating magnetic field An electron microscope comprising: a means for selectively applying and a means for driving an applied magnetic field by a synchronizing signal of an image display means. [Effect] The magnetic domain can be observed at the conventional sample position, and the lens conventionally provided as the deflection correction means can be substituted. Further, it becomes possible to dynamically observe the moving direction and size of the magnetic domain and the motion state of the magnetic domain.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron microscope suitable for observing the motion of magnetic domains by applying a magnetic field to a magnetic sample.

[0002]

2. Description of the Related Art In recent years, much knowledge about the magnetic domain structure has been obtained by observing an electron microscope image of a magnetic sample to which a magnetic field is applied. In particular, in Japanese Examined Patent Publication No. 59-8025, a magnetic field that changes periodically is applied to the sample, and an electron beam is returned to the optical axis by a correction coil placed between the magnetic field application coil and the objective lens and made incident on the objective lens. There is. After passing through the objective lens, only the electron beam at a specific period is taken into the secondary electron multiplier by the trigger signal from the magnetic field applying means and the image is displayed on the cathode tube.

[0003]

Conventionally, since the magnetic field applying means and the deflection correcting means are located above the objective lens, it is necessary to provide the sample holder not only at the objective lens position but also at the magnetic field applying means position. Furthermore, only a static image of a specific period of the applied magnetic field could be displayed.

[0004]

In the present invention, a magnetic field applying means is arranged between objective lenses so that a DC magnetic field or an AC magnetic field having an arbitrary phase, period and amplitude can be applied to a sample, The deflection correcting means arranged between the imaging lenses is used to correct the deflection of the electron beam by the magnetic field applying means, and the motion of the magnetic domain is observed. Further, the magnetic field application means and the deflection correction means are driven by a synchronization signal from the image display means, and the motion of the magnetic domain due to the applied magnetic field can be dynamically observed.

[0005]

[Function] A DC current generated by a magnetic field applying power source or an arbitrary phase in the magnetic field applying means installed between the objective lenses,
An alternating current with a period and amplitude is applied with an arbitrary synchronization signal. The electron beam incident on the objective lens is deflected by the magnetic field applying means. The X component and the Y component of the magnetic field application means are added with respective currents distributed at arbitrary ratios and applied to the deflection correction coil to deflect the electron beam back to return the electron beam on the optical axis for correction. Further, the magnetic field applying means and the correcting means are driven by the synchronizing signal of the image display means, and the images in the case where the magnetic field is applied and the case where the magnetic field is applied are alternately displayed for each screen, and the images are displayed in the same phase or in different phases, and the direction of movement of the magnetic domain is displayed. The size is observed dynamically.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a magnetic field applying means provided in an objective lens, a correcting means for correcting the deflection of an electron beam due to the applied magnetic field, and a static magnetic field or an arbitrary phase, period, amplitude in the magnetic field applying means. It is possible to dynamically observe a magnetic sample by applying an alternating magnetic field, which will be described below with reference to the drawings.

FIG. 1 is a block diagram for explaining one embodiment of the present invention. In the figure, 1 is an electron gun, and an electron beam 2 generated by the electron gun 1 is incident on a focusing lens 3 to form a parallel beam. And is incident on the magnetic sample 6 along the optical axis 4. Two coils 7a and 7b for applying a magnetic field to the sample 6 are arranged in the objective lens 5 to generate magnetic fields in the X and Y directions, respectively. A direct current or an arbitrary alternating current is supplied from the magnetic field applying power source 20 to the coils 7a and 7b. As the alternating current, an arbitrary signal of the synchronizing circuit 14 or an alternating signal of a sine wave, a square wave, a triangular wave or the like having an arbitrary period generated in the sine wave generating circuit 15 by the synchronizing signal 21 from the image display means 11 is supplied to the phase adjuster 16. It is introduced, converted into an alternating current of arbitrary phase and amplitude, amplified by the current amplifiers 17a and 17b, and introduced into the coils 7a and 7b. Therefore, an arbitrary magnetic field is applied to the sample 6 by the coils 7a and 7b, and the magnetic portion in the sample 6 moves. The electron beam is deflected by the magnetic field applied to the sample 6 and enters the correction coils 8a and 8b composed of two coils. The correction coils 8a and 8b apply a magnetic field that cancels the deflection of the electron beam 2 received by the coils 7a and 7b to return the electron beam to the optical axis 4 for correction. At this time, the currents in the X and Y directions of the coils 7a and 7b are distributed to the correction coils 8a and 8b by the distributors 18a and 18b at arbitrary ratios as shown in FIG. Coil 7 because it is amplified and applied by 19a and 19b
It is electrically synchronized with a and 7b. Correction coil 8a,
An image forming lens 9 is arranged in the subsequent stage of 8b, and an image formed by the image forming lens 9 is converted into an optical image by a converting means 10 for picking up the image, and then displayed by an image displaying means 11. Of course,
Another imaging lens may be arranged in front of the deflection correction coil.

[0008]

According to the present invention, it is not necessary to newly provide a sample position above the objective lens, and it becomes possible to observe magnetic domains at the conventional sample position. Further, it becomes possible to substitute the image shift coil as the deflection correction means.

Further, the magnetic field applying means is driven by the synchronizing signal of the image display means, and the electron beam images when the magnetic field is applied and when the magnetic field is not applied are alternately displayed on the image display means. By selecting the phase of the applied AC magnetic field, it is possible to observe the motion direction and size of the magnetic domain as a static image when the applied magnetic field is in phase, and to see how the magnetic domain moves when the phase is changed. It becomes possible to observe dynamically.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a detailed explanatory diagram of FIG.

[Explanation of symbols]

1 ... Electron gun, 2 ... Electron beam, 3 ... Focusing lens, 4 ... Optical axis,
5, 5a, 5b ... Objective lens, 6 ... Sample, 7a, 7b ...
Coil, 8a, 8b ... Correction coil, 9 ... Imaging lens, 1
0 ... conversion means, 11 ... image display means, 14 ... synchronization circuit, 1
5 ... Sine wave generating circuit, 16 ... Phase adjuster, 17a, 17
b, 19a, 19b ... Current amplifier, 18a, 18b ... Distributor, 20 ... Magnetic field applying power supply, 21 ... Synchronizing signal.

Claims (1)

[Claims] 1. An electron gun, a converging lens for converging an electron beam generated from the electron gun onto a sample, an objective lens into which an electron beam transmitted through the sample is incident, and a magnetic field is applied to the sample. In an electron microscope comprising: means, a plurality of image forming lenses for forming an image by the electron beam, means for capturing an image by the image forming lens, and means for displaying the image, A means for correcting the deflection of the line is provided between the objective lens and the imaging lens, and a means for driving the magnetic field applying means and the deflection correcting means with a signal from the image display means is provided. electronic microscope.