JPH0772747B2 - Device for observing magnetized state of magnetic material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetization state observing device for detecting a magnetization state of a magnetic body such as a magnetic recording medium by utilizing a magneto-optical effect, and particularly, The present invention relates to an apparatus for observing a magnetized state of a magnetic body, which is suitable for observing a fine magnetized state with a high-quality image.

[Prior Art] As a method for observing a fine magnetization state of a magnetic body such as a magnetic recording medium, a method utilizing a magneto-optical effect is known. This method has an advantage that a fine magnetized state can be detected by condensing a light beam incident on a magnetic body in a minute area. However, the magneto-optical effect of a magnetic material used for a magnetic recording medium or the like is generally very small, and it is extremely difficult to directly observe its magnetization state.

In order to solve this difficulty, for example, JP-A-53-5077
As described in Japanese Patent Publication No. 7, a soft magnetic perpendicular magnetization film having a relatively large magneto-optical effect is used as a magnetic transfer body, and the magnetic transfer body is brought into contact with a magnetic recording medium,
A method is used in which the magnetization state of the magnetic recording medium is transferred and the transferred magnetic state is observed.

Further, as a conventional technique, as described in Japanese Patent Laid-Open No. 59-30075, a Faraday element is inserted between a magnetic body and an analyzer, and a magneto-optical effect image is generated by the magneto-optical effect of the Faraday element. There has been known a magnetic domain observing device which inverts the gradation and takes the difference by a differential amplifier to obtain a high contrast signal indicating the magnetic characteristics of a magnetic material.

[Problems to be Solved by the Invention] In the former conventional technique described above, the observed magnetization state is
When measuring the shape and position of a magnetized region of a magnetic substance by imaging with an image sensor such as a camera, sufficient contrast cannot be obtained in the image, and uneven sensitivity, thermal noise, illumination unevenness, and magnetic surface of the image sensor are observed. There is a problem that it is difficult to extract an observation image of the magnetization state due to image noise such as scratches.

Further, in the latter conventional technique, the Faraday element itself is expensive, and further, the polarization angle is changed by passing through the Faraday element, and the polarization is desensitized, and the linearly polarized light is gradually changed to the elliptically polarized light, thereby improving the image quality. No consideration was given to the fact that it could not be achieved.

The present invention has been made to solve the above-mentioned problems of the prior art, the object of the present invention, without disturbing the relative linear polarization state between the polarizer and the analyzer by a simple configuration, It is an object of the present invention to provide an apparatus for observing the magnetization state of a magnetic body, which enables observation of the magnetization state of the magnetic body with a high-quality image.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the structure of the magnetization state observation apparatus for a magnetic body according to the present invention has a polarizer for converting light from a light source into linearly polarized light, and Lens linear optical system for injecting the linearly polarized light of the above into the magnetic substance or the soft magnetic film to which the magnetization state of the magnetic substance is transferred, and the linearly polarized light whose polarization plane is rotated by the magneto-optical effect of the magnetic substance or the soft magnetic film. In the apparatus for observing a magnetized state of a magnetic material, which is provided with an analyzer for performing an optical image obtained from the analyzer, a holder for holding the polarizer or the analyzer is driven to rotate about an optical axis. Then, by changing the relative polarization angle between the polarizer and the analyzer, the polarization angle changing mechanism for reversing the shades of the optical image obtained from the analyzer, and the shade obtained from the analyzer are reversed to each other. Image pickup means for picking up the imaged optical image, storage means for storing each of the optical image signals obtained by inverting the shades obtained by the image pickup means, and the inverted optical image signals stored in the storage means. A high-contrast gray image obtained from this arithmetic processing circuit, which is provided with an arithmetic processing circuit for reading and subtracting each to obtain a high-contrast gradation image signal corresponding to the magnetization direction of the magnetic substance or the soft magnetic film. The magnetization state of the magnetic material or the soft magnetic film is observed by a signal.

[Operation] When linearly polarized light transmitted through a polarizer is incident on a magnetic material, the plane of polarization is rotated in the positive or negative direction according to the magnetization direction of the magnetic material due to the magneto-optical effect. The output state of which the polarization plane is rotated is transmitted through an analyzer to form an image on an image sensor, whereby the magnetization state of the magnetic material is captured as a grayscale image. This includes uneven sensitivity of the device, thermal noise, uneven lighting, and scratches on the magnetic surface.

Therefore, by changing the relative polarization angle between the polarizer and the analyzer by a polarization angle changing mechanism such as a motor provided in the polarizer or the analyzer, the magnetization direction imaged before the change is dealt with. It is possible to obtain the grayscale image and the image in which the grayscale is reversed. In this case, in the images before and after the change, the image noise such as the sensitivity unevenness of the image pickup device, the thermal noise, the uneven illumination, and the scratch on the surface of the magnetic body does not change at all. Therefore, by performing subtraction processing on the images captured before and after the change using the arithmetic processing circuit, the contrast of the grayscale image corresponding to the magnetization direction is doubled, and the image noise is erased. Is achieved.

[Examples] Hereinafter, the present invention will be described with reference to Examples.

FIG. 1 is a schematic configuration diagram of an apparatus for observing a magnetized state of a magnetic body according to a first embodiment of the present invention.

This embodiment is used for observing the magnetization state of a signal recorded on a magnetic recording medium 9 relating to an opaque magnetic material having perpendicular magnetic characteristics.

In this case, the magnetic transfer member 8 (for example, a thin film of gadolinium-iron alloy having a thickness of 1 μm) relating to the soft magnetic film is brought into close contact with the surface of the magnetic recording medium 9, and the magnetized state transferred to the magnetic transfer member 8 is set. To observe.

Explaining the configuration of this device, 1 is a light source, 2 is a polarizer for converting the light from this light source 1 into linearly polarized light, and this polarizer 2 is fixed to a holder 3 having a gear part on its outer periphery. ing. 6 is a semi-transparent mirror and 7 is a lens. These are
An optical element for making linearly polarized light from the polarizer 2 incident on the magnetic transfer film 8 is configured. Reference numeral 10 is an analyzer for detecting linearly polarized light whose polarization plane is rotated by the magneto-optical effect of the magnetic transfer member 8. Reference numeral 11 is an image sensor capable of capturing an image of output light from the analyzer 10. Is a motor according to a polarization angle changing mechanism in which a gear 4 attached to the motor shaft end meshes with a gear portion of the holder 3. By driving the motor 5 to rotate the polarizer 2, It is possible to change the relative polarization angle between the analyzer 10 and the analyzer 10, and to reverse the shade of the image captured by the image sensor 11 before and after the change. 12 is a storage device capable of storing the image before the change (before the inversion), 13 is a storage device capable of storing the image after the change (after the inversion), and 14 is the storage device An arithmetic processing circuit capable of performing subtraction processing on the both images stored in 12, 13 is an output device such as a cathode ray tube that outputs the subtracted image.

The operation of the device thus configured will be described with reference to FIGS.

FIG. 2 shows a magnetization pattern of the magnetic transfer body, which is observed by the magnetization state observation apparatus according to FIG.
(A) is an image diagram before rotating the polarizer, (b) is an image diagram after rotating the polarizer, and (c) 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. This linearly polarized light is a semi-transparent mirror
6, incident on the magnetic transfer body 8 via the lens 7. The magnetized state of the magnetic recording medium 9 is transferred to the magnetic transfer body 8, and the reflected light from the magnetic transfer body 8 rotates in a positive or negative polarization plane depending on the magnetization direction of the magnetic transfer body 8. When the transmission axis direction of the analyzer 10 is a direction that selectively transmits the positively rotated polarization plane, the image transmitted through the analyzer 10 and formed on the image pickup element 11 is A portion having a magnetization direction for positively rotating the polarization plane is detected brightly, while a portion having a magnetization direction for negatively rotating the polarization plane is detected darkly, and the output signal of the image pickup element 11 is detected by the storage device 12.
Memorized in. Next, the motor 2 rotates the polarizer 2 by the set rotation angle, the polarization plane of the reflected light from the magnetic transfer body 8 also rotates, and it rotates in the negative direction with respect to the transmission axis direction of the analyzer 10. The polarizer 2 is positioned at a position where the plane of polarization selectively transmits. At this time, the image sensor 11
The image formed in [Fig. 2 (b)] is an image in which the shade is inverted with respect to the image taken immediately before rotating the polarizer 2 [Fig. 2 (a)]. It is stored in the device 13. Then, 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 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 an image of high quality can be observed.

Another embodiment will be described below.

FIG. 3 is a schematic configuration diagram of a magnetized state observing device according to a second embodiment of the present invention.

This embodiment is used for observing the magnetic state of a signal recorded in a magnetic recording medium 9A which is a transparent (or extremely thin) magnetic material having perpendicular magnetic characteristics.
In this case, the magnetic transfer member 8 used in the embodiment shown in FIG. 1 is unnecessary.

In FIG. 3, the same reference numerals as in FIG. 1 denote the same parts. And 7A and 7B are lenses related to the optical element.

The operation of this device is similar to that of the device shown in FIG. 1, and linearly polarized light transmitted through the polarizer 2 is condensed by the lens 7A, transmitted through the magnetic recording medium 9A, and the lens 7B and the analyzer 10
And is imaged on the image pickup element 11, and this image is stored in the storage device 12. The motor 5 rotates by the set rotation angle, and the image in which the gray scale is inverted from the image is stored in another storage device 13
Memorized in. 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 magnetized state observing apparatus according to a third embodiment of the present invention.

This embodiment is used for observing the magnetization state of a signal recorded in the magnetic recording medium 9B relating to a magnetic substance having in-plane magnetic characteristics.

In FIG. 4, the same reference numerals as those in FIG. 3 denote the same parts.

The operation of this device is similar to that of the device shown in FIG. 1, and linearly polarized light transmitted through the polarizer 2 is condensed by the lens 7A and obliquely enters the magnetic recording medium 9B. The light is transmitted through the lens 7B and the analyzer 10 to form an image on the image pickup device 11, and this image is stored in the storage device 12. Similarly, a high quality image is output to the output device 15.

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 the analyzer 10 is rotated. However, the same effect is obtained.

[Effects of the Invention] As described in detail above, according to the present invention, the magnetization state of a magnetic substance can be changed by a simple structure without disturbing the relative linear polarization state between the polarizer and the analyzer. It is possible to provide an apparatus for observing a magnetized state of a magnetic material that enables observation with a high-quality image.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a magnetized state observing apparatus according to the first embodiment of the present invention, and FIG. 2 is a magnetic transfer member observed by the magnetized state observing apparatus shown in FIG. FIG. 3 is a schematic view of an image showing the magnetization pattern of FIG. 3, and FIGS. 3 and 4 are schematic configuration diagrams of a magnetization state observing device for a magnetic body according to the second and third embodiments of the present invention, respectively. 1 ... Light source, 2 ... Polarizer, 5 ... Motor, 6 ... Semi-transparent mirror, 7,7A, 7B ... Lens, 8 ... Magnetic transfer body, 9,9A, 9B ...
… Magnetic recording medium, 10 …… Analyzer, 11 …… Image sensor, 12,1
3 ... storage device, 14 ... arithmetic processing circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-59-30075 (JP, A) JP-A-62-102103 (JP, A) JP-A-56-124064 (JP, A) JP-A-47- 28967 (JP, A) JP 53-50777 (JP, A) JP 51-131670 (JP, A) JP 56-142453 (JP, A)

Claims (1)

[Claims] 1. A polarizer for converting light from a light source into linearly polarized light,
A lens optical system for allowing linearly polarized light from this polarizer to enter the magnetic body or the soft magnetic film on which the magnetization state of the magnetic body is transferred, and the plane of polarization is rotated by the magneto-optical effect of the magnetic body or the soft magnetic film. An analyzer for detecting through linearly polarized light, in the magnetization state observation device of the magnetic body, which is adapted to capture an optical image obtained from this analyzer, a holder for holding the polarizer or the analyzer, the optical axis A polarization angle changing mechanism for rotating relative to the center to change the relative polarization angle between the polarizer and the analyzer, and inverting the shades of the optical images obtained from the analyzer with each other; Image pickup means for picking up an optical image in which shades are inverted to each other, storage means for storing each of the optical image signals obtained by the image pickup means in which shades are inverted to each other, and stored in this storage means An arithmetic processing circuit for reading out and subtracting each of the inverted optical image signals thus obtained to obtain a grayscale image signal with high contrast corresponding to the magnetization direction of the magnetic body or the soft magnetic film. An apparatus for observing a magnetized state of a magnetic body, characterized in that the magnetized state of a magnetic body or a soft magnetic film is observed by a high-contrast gray-scale image signal obtained from a processing circuit.