JPH05307719A - Magnetic domain observation and magnetization measuring instrument - Google Patents

Abstract

PURPOSE:To obtain the instrument capable of performing two different kinds of measurement as magnetic domain observation and magnetization measurement in a short time by utilizing the Kerr effect. CONSTITUTION:This is a microscopic device for detecting a magnetic domain pattern of a magnetic substance as to be light and shade corresponding to the size of magnetization and a difference in its direction by the longitudinal Kerr effect with polarized light. The device is equipped with a CCD camera 2 and a light oscilloscope 4 as detectors, and is also equipped with a rotatable mirror 1 between the CCD camera 2 and a head 3 of the light oscilloscope, where by making the light to be detected by changing the angle of the mirror 1 incident upon either the CCD camera 2 or the head 3 of the light oscilloscope, the magnetic domain observation and magnetization measurement is carried out in a short changeover time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to magnetic domain observation and magnetization measurement of a magnetic film of a magnetic head.

[0002]

2. Description of the Related Art There are the following devices for observing the magnetic domains of a magnetic material sample by utilizing the Kerr effect. After the light from the light source is linearly polarized, it is condensed and irradiated so as to form a spot of about 3 μm on the surface of the magnetic material. The rotation angle of the plane of polarization due to the Kerr effect of the reflected light increases in proportion to the component in the direction parallel to the magnetization vector of the magnetic material with respect to the direction when the incident light is projected onto the surface of the magnetic material sample. Of the reflected light, only the light whose polarization plane is rotated by the Kerr effect is passed through the analyzer, and the passed light is detected. While moving the magnetic sample, measure the magnetization of each point,
An image of the magnetic domain pattern is assembled based on the individual magnetization values. Hereinafter, this method is called a scanning method. Further, there is a method of collectively irradiating the entire surface of the magnetic material sample with light from a light source to obtain an image of the magnetic domain pattern of the magnetic material sample at one time, and this method is hereinafter referred to as a collective irradiation method.

With the conventional scanning method, an image of a magnetic domain pattern of a magnetic material sample can be obtained and the magnetization of a minute region can be measured. However, an image is obtained in order to assemble an image of the magnetic domain pattern from the magnetization measurement of each point. It takes a long time.
Therefore, quick measurement cannot be performed.

In the conventional collective irradiation method, it is impossible to measure the magnetization in a minute region because of the principle of irradiating the entire surface of the magnetic material sample with light.

Obtaining an image of the magnetic domain pattern of the magnetic material sample and measuring the magnetization of a minute area are both important information for evaluating the magnetic material. In order to correlate the results of both, it is desirable to perform measurements using the same light source, the same polarizer, and the same analyzer, and both measurements can be performed with the same device with minimal changes. Therefore, an apparatus that can measure both of them in a short time has been desired.

[0006]

As described above, in observing the magnetic domain of the magnetic substance and measuring the magnetization of the minute region using the Kerr effect, the same light source, objective lens, polarizer, It is necessary to use an analyzer. Further, in order to shorten the experiment time, it is necessary to shorten the time required for the measurement itself, and in the case of magnetic domain observation, the collective irradiation method is superior in this respect. For these reasons, it is necessary that the magnetic domain observation can be performed by the collective irradiation method, and the magnetization measurement of a minute region can be performed in a short switching time. Therefore, a device having a device configuration having these functions is required.

[0007]

In order to achieve the above object, in the apparatus of the present invention, a lens for collecting light from a light source installed between a light source and an objective lens is mechanically changed to one having a different focal length. By exchanging and mechanically moving this installation position, the diameter and solid angle of the light incident on the objective lens are changed, and as a result, the irradiation area on the surface of the magnetic sample without changing other optical parts. Has a diameter of several μm to 1
We made it possible to change to about 00 μm. Further, a total reflection mirror is rotatably installed between the image detector and the light intensity detector and at a position where the light passing through the analyzer passes.

By rotating this total reflection mirror,
The light passing through the analyzer is allowed to enter either the light receiving portion of the image detector or the light receiving portion of the light intensity detector. Although it is conceivable to use a prism instead of the mirror, it is basically the same means. In this way, the observation of the magnetic domain of the magnetic substance and the measurement of the magnetization of the microscopic region can be performed using the same light source, polarizer, objective lens and analyzer in a short switching time.

[0009]

In the present invention, with the above configuration, it is possible to perform two different measurements, that is, observation of magnetic domains of a magnetic material and measurement of magnetization of a minute area, in a very short switching time. Simply change the lens that collects the light from the light source to one with a different focal length, move the mounting position, and rotate the total reflection mirror installed between the image detector and the light intensity detector. You can switch with. Semiconductor laser light source, polarizer,
Since it is not necessary to change the positions of the objective lens and the analyzer, the position adjustment of the optical parts is done by adjusting the lens that collects the light from the light source and installing all the components between the image detector and the light intensity detector. Since it is only necessary to adjust the angle of the reflection mirror, it is possible to switch in a very short time.

[0010]

EXAMPLES Specific examples will be described in detail below. FIG. 1 is an enlarged view of a detection unit of the magnetic domain observation and magnetization measurement device of the present invention. (FIG. 1) will be described. The detection unit includes a total reflection mirror 1, a CCD camera 2, an optical oscilloscope head 3, and an optical oscilloscope 4.
By changing the direction of the total reflection mirror 1, it is possible to irradiate the light entering the detector to the light receiving portion of the CCD camera 2 or the light receiving portion of the head 3 of the optical oscilloscope. The CCD camera 2 is irradiated with light when observing the magnetic domains, and the light receiving portion of the head 3 of the optical oscilloscope is irradiated with light when the magnetization is measured. The light applied to the light receiving portion of the head 3 of the optical oscilloscope is subjected to photoelectric conversion processing at high speed and is sent to the optical oscilloscope 4 as an electric signal.

FIG. 2 shows a magnetic domain observation and magnetization measuring device according to the present invention. (FIG. 2) will be described. The semiconductor laser light source 5 is driven by the light source driving device 6 to emit light. The light from the semiconductor laser light source 5 is condensed by the lens 7 at the position of the field stop 8. The spot diameter of the light at this time is smaller than the size of the field stop 8, and the light does not contact the field stop 8. The light condensed at the position of the field stop 8 becomes linearly polarized light by passing through the polarizer 9, passes through the edge of the objective lens 10, and is applied to the magnetic film of the thin film magnetic head 11.

In the thin film magnetic head 11, the magnetic film is excited by applying a current to the coil from the head driving device 12. Of the reflected light from the magnetic film of the thin-film magnetic head 11, the position of the analyzer 13 is set in advance in a crossed Nicol positional relationship with respect to the polarizer 9 so that only the light whose polarization plane is rotated by the Kerr effect passes through. , Only the light whose polarization plane is rotated by the Kerr effect is transmitted. The light passing through the analyzer 13 passes through the relay lens 14 and the detecting portion 15
Detected by. In the detection unit 15, both the light receiving unit of the CCD camera 2 and the light receiving unit of the head 3 of the optical oscilloscope are installed so as to be at the focal point of the relay lens 14.

FIG. 3 is an enlarged view of the vicinity of the lens 7 shown in FIG. In FIG. 3, the lens 7 is fixed by the lens holder 16. The lens holder 16 is movable along the rail 17. Rail 17 light 18
It is mounted parallel to the path of.

In FIG. 2, the mounting position of the lens 7 is such that the focal position always matches the position of the field stop 8 regardless of the focal length of the lens. By changing the mounting position of the lens 7 and the focal length, the spot diameter of the light with which the magnetic film of the thin film magnetic head 11 is irradiated can be changed from several μm to several hundred μm in diameter. This spot diameter is determined by the beam diameter of the semiconductor laser light source 5, the focal length of the lens 7, and the distance between the lens 7 and the objective lens 10. When the beam diameter of the semiconductor laser light source 5 and the distance between the lens 7 and the objective lens 10 are constant, if the focal length of the lens 7 is short, the spot diameter on the magnetic film of the thin film magnetic head 11 is large, and if the focal length is long, the spot is large. The diameter becomes smaller.

[0015]

By using the magnetic domain observation and magnetization measurement apparatus of the embodiment of the present invention, it is possible to perform two different types of measurement, magnetic domain observation and magnetization measurement, with a short switching time and a short measurement time. became.

[Brief description of drawings]

FIG. 1 is an enlarged view of a detection unit of a magnetic domain observation and magnetization measurement device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a magnetic domain observation and magnetization measurement device according to an embodiment of the present invention.

FIG. 3 is an enlarged view of a lens fixing portion in the embodiment of the present invention.

[Explanation of symbols]

 1 Mirror 2 CCD Camera 3 Optical Oscilloscope Head 4 Optical Oscilloscope 5 Semiconductor Laser Light Source 6 Light Source Driving Device 7 Lens 8 Field Stop 9 Polarizer 10 Objective Lens 11 Thin Film Magnetic Head 12 Head Driving Device 13 Analyzer 14 Relay Lens 15 Detecting Unit 16 Lens holder 17 Rail 18 Light

Claims (2)

[Claims] 1. A microscope apparatus for detecting a light and shade of light corresponding to a difference in magnitude and direction of magnetization by a longitudinal Kerr effect by polarized light of a magnetic domain pattern of a magnetic material, and an image detector and a light intensity as a detector. It has a detector, and a mirror is installed between the image detector and the light intensity detector,
The installation position of the lens, which has a function of allowing the light detected by changing the angle of the mirror to enter either the image detector or the light intensity detector, and which is a component of the microscope apparatus. A magnetic domain observation and magnetization measurement device having a function of mechanically moving the lens and mechanically exchanging the lens with a lens having a different focal length. 2. The light to be detected can be made incident on either the image detector or the light intensity detector by changing the angle of a prism installed between the image detector and the light intensity detector. The magnetic domain observation and magnetization measurement device according to claim 1, which has various functions.