JPH01477A - Magnetization state observation device for magnetic materials - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetization state detection device for detecting the magnetization state of a magnetic material such as a magnetic recording medium by using the magneto-optic effect. In particular, the present invention relates to an apparatus for observing the magnetization state of a magnetic material, which is suitable for observing minute magnetization states in high-quality images.

[Prior Art] A method using the magneto-optic effect is known as a method for observing the minute magnetization state of a magnetic material such as a magnetic recording medium. This method has the advantage that a minute magnetization state can be detected by focusing a light beam incident on a magnetic material onto a minute area. However, the magneto-optical effect of magnetic materials used in magnetic recording media and the like is generally very small, and it has been extremely difficult to directly adjust the magnetization state to Nla%.

In order to solve this problem, for example,
As described in Publication No. 0777.

A soft magnetic perpendicular magnetization film with a relatively large magneto-optical effect is used as a magnetic transfer body, and by bringing this magnetic transfer body into contact with a magnetic recording medium, the magnetization state of the magnetic recording medium is transferred, and this transferred magnetic state is transferred. A method of observing is being used.

[Problem to be solved by the invention] The above-mentioned prior art solves the problem that 6='tl? When measuring the shape and position of the magnetized region of a magnetic material by capturing the magnetized state with a TV camera, etc. (& element), sufficient contrast cannot be obtained in one image, and the sensitivity of the image sensor There has been a problem in that it is difficult to extract observed images of the magnetization state due to image noise such as unevenness, thermal noise, uneven illumination, and scratches on the surface of the magnetic material. It wasn't taken into consideration.

An object of the present invention is to provide an apparatus for determining the magnetization state of a magnetic material (vft), which solves the above-mentioned problems of the prior art and can display the magnetization state of a magnetic material in vAr3 with high-quality images. It is something.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the structure of the magnetization state observation device of a magnetic body according to the present invention detects the magnetization state of a magnetic body using a magneto-optical effect. In this apparatus for observing the magnetization state of a magnetic material, there is a polarizer for converting light from a light source into linearly polarized light, and the linearly polarized light from this polarizer is incident on the magnetic material or a soft magnetic film in contact with the magnetic material. an analyzer for detecting linearly polarized light whose plane of polarization has been rotated by the magneto-optic effect of the magnetic material or soft magnetic film, and an image of output light from the analyzer. a polarization angle changing mechanism capable of changing the relative polarization angle between the polarizer and the analyzer and reversing the shading of the image before and after the change; A storage device that can store both images stored in the storage device and an arithmetic processing circuit that can perform subtraction processing on both images stored in this storage device are AM'ff.

More specifically, the relative polarization angle between a polarizer for linearly polarizing light incident on a magnetic material, an analyzer for detecting output light whose plane of polarization has been rotated by the magneto-optical effect, and the polarizer. This system includes a polarization angle changing mechanism that changes the polarization angle, and an arithmetic processing circuit for images taken before and after the change.

[Operation] When linearly polarized light transmitted through a polarizer is incident on a magnetic material, the plane of polarization rotates in the positive or negative direction depending on the magnetization direction of the magnetic material due to the magneto-optic effect. By transmitting this output light with a rotated plane of polarization through an analyzer and forming an image on an image sensor, the magnetization state of the magnetic body is imaged as a gray scale image. This includes uneven sensitivity of the element, thermal noise, uneven lighting, and scratches on the surface of the magnetic material.

Therefore, by changing the relative polarization angle between the polarizer and analyzer using a polarization angle changing mechanism such as a motor installed in the polarizer or analyzer, it corresponds to the magnetization direction imaged before the change. It is possible to obtain a grayscale image and an image whose grayscale is inverted. In this case, in the images before and after the change, image noise such as uneven sensitivity of the image sensor, thermal noise, uneven illumination, and scratches on the surface of the magnetic material does not change at all. Therefore, by subtracting images captured before and after the change using an arithmetic processing circuit, the contrast of the grayscale image corresponding to the magnetization direction is doubled and single-image noise is eliminated, resulting in a significant improvement in image quality. is achieved.

[Example] Hereinafter, the present invention will be explained by examples.

FIG. 1 is a schematic configuration diagram of a device for detecting the magnetization state of a magnetic material according to a first embodiment of the present invention.

In this embodiment, the magnetization state of No.
! As you can imagine, it is used.

In this case, a magnetic transfer body 8 that is a soft magnetic film (for example, a thin film of gadolinium iron alloy with a thickness of 1 μm) is brought into close contact with the surface of the magnetic recording medium 9, and the magnetization state transferred to this magnetic transfer body 8 is Observe.

To explain the configuration of this device, 1 is a light source, 2 is a polarizer for linearly polarizing light from this light g1, and this polarizer 2 is fixed to a holder 3 having a gear portion on the outer periphery. ing. 6 is a semi-transparent mirror, 7 is a lens, and these are:
It constitutes an optical element for making the linearly polarized light from the polarizer 2 incident on the magnetic transfer film 8. 10 is an analyzer for detecting linearly polarized light whose plane of polarization has been rotated by the magneto-optical effect of the magnetic transfer body 8; 11 is an image pickup element capable of capturing an image of the output light from this analyzer 10; 5; is a motor related to a polarization angle changing mechanism in which a gear 4 attached to the end of the motor shaft meshes with the gear part of the holder 3;
By driving the polarizer 2 and rotating the polarizer 2, the polarizer 2
By changing the relative polarization angle between the analyzer 10 and the analyzer 10, the shading of the image captured by the image sensor 11 can be reversed before and after the change. 12 is a storage device that can store the image before the change (before inversion); 13 is a storage device that can store the image after the change (after inversion); 14 is this storage device 12.13
an arithmetic processing circuit 15 capable of subtracting the two images stored in the image data;

An output device such as a cathode ray tube outputs the subtracted signal.

The operation of the apparatus constructed in this way will be explained using FIGS. 1 and 2.

In the second session, W
A? 3 shows the magnetization pattern of the magnetic transfer body, (a) is an image before rotating the polarizer, (b)
) is the image after rotating the polarizer, (c) is the image after rotating the polarizer.
It is an image diagram obtained by subtracting both the images.

When the rotation angle of the polarizer 2 is set in advance and the magnetization state observation device is turned on, the light from the light source 1 is polarized by the polarizer 2 and becomes linearly polarized light. The light enters the magnetic transfer body 8 through the lens 7. The magnetization state of the magnetic recording medium 9 is transferred to the magnetic transfer body 8, and depending on the magnetization direction of the magnetic transfer body 8, the plane of polarization of light reflected from the magnetic transfer body 8 rotates in a positive or negative direction. Analyzer 10
When the direction of the transmission axis of is a direction that selectively transmits a positively rotated plane of polarization, the image transmitted through the analyzer 10 and formed on the image sensor 11 is transmitted through the polarization plane in the magnetic transfer body 8. The part with the magnetization direction that rotates in the positive direction is bright,
- The part with the magnetization direction that rotates the optical surface of the old wound in the negative direction will be detected darkly, and the output signal of the image sensor 11 will be recorded in the memory table ff! 12, the polarizer 2 is rotated by the set rotation angle by the motor 5, and the polarization plane of the reflected light from the magnetic transfer body 8 is also rotated, with respect to the transmission axis direction of the analyzer 10. The polarizer 2 is positioned at such a position that the plane of polarization rotated in the negative direction is selectively transmitted. At this time, the image formed on the image sensor 11 [Fig. 2(b)
] is the image taken just before rotating the polarizer [
2(a)], the image is an image in which the shading is inverted, and is stored in the storage device 13. These two images are subjected to subtraction processing by the arithmetic processing circuit 14, and the processed image [FIG. 2(C)] is output to the output device i! 15.

According to the embodiment described above, the contrast of the grayscale image corresponding to the magnetization direction is doubled, image noise is eliminated, and a high-quality image can be IIQed.

Other embodiments will be described below.

FIG. 3 is a schematic configuration diagram of a device for detecting the magnetization state a of a magnetic body according to a second embodiment of the present invention.

This embodiment is used to abbreviate W4 the magnetic state of a signal recorded on a magnetic recording medium 9A that is transparent (or extremely thin) and has perpendicular magnetic properties. , the magnetic transfer body 8 used in the embodiment shown in FIG. 1 is unnecessary.

In FIG. 3, the same parts as in FIG. 1 are denoted by the same numbers. Further, 7A and 7B are lenses related to optical elements.

The operation of this device is also similar to that of the device shown in FIG. The light passes through and forms an image on the image sensor 11, and this image is stored in the storage device 12. The motor 5 rotates by a set rotation angle, and an image whose density is inverted from the above image is stored in another storage device 13. These two images are subtracted by the arithmetic processing circuit 14, and the processed high-quality image is output to the output device 15.

FIG. 4 is a schematic configuration diagram of a device for detecting the magnetization state of a magnetic body according to a third embodiment of the present invention.

This embodiment is used to vArA the magnetization state of a signal recorded on a magnetic recording medium 9B made of a magnetic material having one-plane magnetic property.

In FIG. 4, the same parts as in FIG. 3 are denoted by the same numbers.

The operation of this device is also similar to the device according to Fig. 1 of Moeki, and the linearly polarized light transmitted through the polarizer 2 is condensed by the lens 7A, enters the magnetic recording medium 9B at an angle, and the reflected light is passes through the lens 7B and the analyzer 10, and the image sensor 11
This image is stored in the storage device 12. Thereafter, high-quality images are output to the output device 15 in the same manner.

In each of the above embodiments, the relative polarization angle between the polarizer 2 and the analyzer 10 is changed by rotating the polarizer 2, but it is preferable to rotate the analyzer 10 instead. However, the same effect can be achieved.

[Effects of the Invention] As described above in detail, according to the present invention, it is possible to provide a magnetization state observation device of a magnetic material, which can observe the magnetization state of a magnetic material using high-quality images.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a magnetization state observation device for a magnetic material according to a first embodiment of the present invention, and FIG. 2 is a magnetic transfer body observed by the magnetization state observation device according to FIG. The image diagram showing the magnetization pattern of the second embodiment of the present invention and FIGS. FIG. 7 is a schematic configuration diagram of a device for observing the magnetization state of a magnetic body according to a third embodiment. 1... Light source, 2... Polarizer, 5... Motor, 6...
...Semi-transparent mirror, 7,7. A, 7B...Lens 58...
Magnetic transfer body, 9.9A, 9B...magnetic recording medium, 10
...Analyzer, 11...Image sensor, 12.13...
Storage device, 14... Arithmetic processing circuit.

Claims (1)

[Claims] 1. In a magnetization state observation device for a magnetic material, which detects the magnetization state of a magnetic material using the magneto-optical effect,
a polarizer for converting light from a light source into linearly polarized light; an optical element for making the linearly polarized light from the polarizer incident on a magnetic material or a soft magnetic film in contact with the magnetic material; an analyzer for detecting linearly polarized light with a rotated plane of polarization due to the magneto-optical effect of a magnetic film; an image sensor capable of capturing an image of output light from the analyzer;
A polarization angle changing mechanism capable of changing the relative polarization angle between the polarizer and the analyzer and inverting the shading of the image before and after the change, and storing both images with mutually inverted shading. 1. An apparatus for observing the magnetization state of a magnetic body, comprising: a storage device capable of performing subtraction processing; and an arithmetic processing circuit capable of subtracting the two images stored in the storage device.