JPH0665883U - Micro domain structure observation device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a fine domain structure observing device capable of observing a magnetic domain structure of a magnetic material with a larger magnifying power than ever before for observing the magnetic domain structure. [Structure] Light from a light source is emitted through a polarizer, and emitted polarized light is made incident on the one side not including the central axis of the objective lens and perpendicularly to the objective lens, and the emitted light is enhanced as necessary. A means capable of applying a magnetic field is obliquely projected onto a micro domain structure observation material provided in the vicinity thereof, and the oblique reflected light is again incident on the other side not including the central axis of the same objective lens, and then emitted. A microscopic domain structure observing device that observes polarized light emitted from light passing through an analyzer as a magnetic domain image.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Field of the Invention The present invention relates to an apparatus for observing a micro domain structure of a magnetic material. 2. Description of the Related Art Conventionally, an observation means using polarized light by the magnetic Kerr effect has been known as an observation means for magnetic domain structure of a magnetic material. However, when observing, these devices irradiate polarized light from the oblique direction to the sample surface to be measured, which is provided with a means for applying a magnetic field to the side as an observing device, and observe the reflected light. The objective lens that has a magnifying power of about 1 to 4 times at most is necessary because the focal length of the objective lens must be increased when observing the sample. Could not be used. Further, in the conventional technology in which the optical axis passes through the central axis of the objective lens, it is impossible to observe the magnetic domain structure when the magnetization direction of the magnetic material to be measured is in the horizontal direction (in-plane direction). . Furthermore, in the prior art, since it is necessary to install a coil near the sample, it is necessary to cut and use the observation sample into a size of about 10 mm to 30 mm square. DISCLOSURE OF THE INVENTION The present invention relates to a magnetic material such as a magnetic film or a magnetic material that is a magnetic domain structure observation sample. The magnetic domain structure in a minute region is 1 to 40 times by an objective lens, and 1 to 1 by direct observation. It is an object of the present invention to provide a fine domain magnetic domain structure observing device capable of observing at a magnification of 400 times and an image processing observation of about 2.5 to 1000 times. Here, the magnetic material as the observation sample may be an ordinary magnetic soft material such as a magnetic tape, a floppy disk, a video tape, etc., but a so-called magnetic hard material, particularly a metal tape, sputter or plating, It may be a hard disk formed by vapor deposition, a magnetic head, an amorphous alloy ribbon, or the like, and these magnetic materials can be observed even if they are vertically magnetized materials (vertically magnetized films). ) It is an object of the present invention to provide an apparatus for observing a minute domain structure of a magnetic material that can be observed even with a magnetized material [horizontal (in-plane) magnetized film]. It is also an object of the present invention to provide an apparatus capable of observing a micro domain structure in a non-destructive manner without cutting, even if the observation sample is as large as 3 mm to 300 mm square or about φ. The present invention relates to a magnetic Kerr effect measuring means for emitting light from a light source through a deflector and emitting polarized light on one side not including the central axis of the objective lens. Incident light perpendicularly to the sample, projecting the emitted light onto a sample for observation of a micro domain structure made of a magnetic material provided with a means capable of applying a strong magnetic field as needed, and the reflected light is again the same. Is a device for observing a micro domain structure, characterized in that polarized light is made incident on the other side not including the center of the objective lens, and the emitted light is passed through an analyzer and emitted. Here, means capable of applying a strong magnetic field as needed is an iron core coil capable of mainly forming a strong magnetic field of ± 0.1 KOe or more, preferably ± 1 KOe to ± 10 KOe, for example, a Weiss type electromagnet in a minute domain domain. This means is provided in the vicinity of the structure observation sample, for example, in the vicinity of this sample or on the side of this sample. Further, the iron core for an electromagnet used here has, for example, a shape as shown in FIGS. 1 and 2, and is constituted by a coil having a special shape including a coil winding portion, an arm portion, a taper portion and a connection portion. An air gap portion having a width of about 1 to 5 mm is formed. As a result, any desired portion of the sample having a size of about 3 mm to 300 mm square or about φ can be made into a taper portion of the iron core for the electromagnet without destroying the magnetic material which is the sample for observing the micro domain structure and without destroying it. The micro domain structure can be advantageously observed by making it close to the air gap portion constituted by. In the case of a sample for observing a fine domain magnetic domain structure having a size of 3 mm to 300 mm square or O, a magnet having a conventionally known iron core coil is used in the vicinity of the sample for observing the fine domain magnetic domain structure in place of the special shape core coil. It can also be installed and configured in the. Next, the means for observing the polarized light that passes through the analyzer and exits may be a visual means through an eyepiece lens, but may also be an electron beam imaging tube, for example, a means combining a vidicon camera, a carnicon camera, etc. and a monitor television. . However, a more preferable means is an observation means which uses a CCD camera and is combined with a real-time TV image processing means. As a magnetic material that is a sample for observing a magnetic domain structure in a minute range that can be used in the present invention, a magnetic material using a ferrite material, a sendust material, a permalloy material, or the like can be preferably used, but a magnetic soft material, Any of the magnetic hard materials can be used. Here, the magnetic soft material includes, for example, audio magnetic tape, floppy disk, video tape, magnetic card, magnetic ticket, magnetic head, amorphous metal ribbon, and the magnetic hard material includes, for example, metal tape and sputter. Alternatively, there are hard disks, magnetic disks, magnetic drums, etc. formed by plating or vapor deposition. These magnetic materials may be perpendicularly magnetized materials (vertical magnetized films), but may also be horizontal (in-plane) magnetized materials [horizontal (in-plane) magnetized films]. The present invention will be described in detail with reference to the drawings. The magnetic Kerr effect measuring means that can be used in the present invention is a light source 1, for example, a laser beam generating means, an ultrahigh pressure mercury lamp, a xenon lamp or a halogen lamp. The generated light is taken out as linear or elliptical polarized light of 400 mμ to 550 mμ depending on the sample by the condenser lens 2, the pinhole 3, the collimator lens 4, the filter 5 and the polarizer 6, and the reflecting mirror 7 After that, a means capable of vertically entering the objective lens 8 on one side not including the central axis of the objective lens 8 and applying a strong magnetic field to the emitted light thereof, for example, an iron core coil (electromagnet) 11 is provided in the vicinity thereof. Is projected onto the magnetic material 10, which is a sample for observing the magnetic domain structure in the minute region, and the reflected light is again focused on the center of the same objective lens 8. The light is made incident on the other side that does not include the axis, the emitted light is made to pass through the analyzer 12 through the reflecting mirror 7, and, if necessary, after being made to pass through the filter 5 ′, and then observed through the pinhole 3 ′ eyepiece lens 13. The means 14 is provided. Here, in order to observe the magnetic domain structure of the magnetic domain, the polarized light emitted from the objective lens is incident and reflected on the sample for observing the magnetic domain structure at an incident angle and a reflection angle of about 45 °. Next, the iron core coil 11 used here is composed of an iron core 11-1 and a coil 11-2, and it is preferable to use a soft iron material having a high magnetic permeability for the iron core 11-1. For example, as shown in FIGS. 1 and 2, the iron core 11-1 includes a coil winding portion 11-1-1, an arm portion 11-1-2, a taper 11-1-3, and a connector portion 11-1-. 4 and the like, and the tapered portion 11-1-3 constitutes an air gap portion 11-1-5 having a width of about 1 to 5 mm. A magnetic material, which is a sample for observing a fine domain magnetic domain structure having a size of about 3 mm to 300 mm square or φ, may be cut into this air gap portion to be used as a sample piece for observation. Any part desired to be observed can be closely observed. However, the air gap is the magnification of the lens used in the device of the present invention, N.V. A. (Numerical Aperture). In the device of the present invention, when the magnetic material, which is the sample for observing the micro domain structure, is a hard material, it is usually necessary to generate a high magnetic flux density of 0.1 KGause to 10 kGause, and therefore it is necessary to apply a strong magnetic field. Particularly preferably, it is preferable to combine a magnetic Kerr effect measuring device using an electromagnet with a CCD camera and a real-time TV image processing device. In the present invention, the observing means 14 may be a visual means or a means for taking a direct photograph, but an electron beam image pickup tube, for example, a vidicon camera or a carnicon camera is combined with a monitor television. It is also possible to use the means used. In this case, the magnification of the image can be 1 to 40 times as an objective lens and 1 to 10 times as an eyepiece, so that an overall magnification of about 1 to 400 times can be obtained. However, when the CCD camera 14-1 and the real-time TV image processing device 14-2 are used as the observing means, the whole device is 2. It is possible to obtain an image with a magnification of about 5 to 1000 times. The case of using the observation means that uses a combination of the CCD camera and the real-time TV image processing device will be described below. The polarized light emitted from the eyepiece lens 13 as described above is first received by the CCD camera 14-1 shown in FIG. A CCD (Charge Coupled Device) camera is a MOS diode formed of metal-oxide-semiconductor, and has a CCD all-solid-state image sensor in which gate electrodes are arranged in a mosaic pattern. It consists of parts. A signal obtained by photoelectrically converting the light received by the CCD camera by the CCD all-solid-state image sensor of the camera head is output as a video signal by analog or digital scanning of the camera controller. The output signal from the CCD camera 14-1 is sent to the real-time TV image processing unit 14-2 shown in FIG. The real-time image processing unit includes an A / D conversion unit 17, a calculation processing unit (memory writing) 18, a memory unit 19, a calculation processing unit (memory reading) 20, an enhancement processing unit 21, and an D / D conversion unit that operate at high speed. The A conversion unit 22 is included. First, the image when the magnetic field is not applied to the micro domain structure observation sample 10 is integrated by the arithmetic processing unit 18 (30) (FIG. 4) and stored in the memory unit 19 to be a background image (31). Next, while applying a strong magnetic field to the micro domain structure observation sample 10 and subtracting the background image from the video signal from the CCD camera 14-1, the memory 19 is used to perform averaging processing (32) and simultaneously enhance processing. The contrast is emphasized in the section 21 (33 to 37) and is displayed on the TV through the D / A conversion section 22 (28). By subtracting the background image here, it is possible to remove the variation of the CCD camera output voltage due to the nonuniformity of the surface of the sample for observing the magnetic domain structure in the minute region, and to extract only the changed portion due to the magnetic field. The integration in the arithmetic processing unit adds the same video several times, which brings about an S / N improvement for a still image, where N is the number of additions. Has an S / N improving effect. On the other hand, in averaging, input image data and memory image data are weighted and used as write data in the memory, which is an S / N improvement for moving images. If the weighting coefficient is K Has an S / N improving effect. The value of K is set with the remote control boxes 24 and 25. Further, the enhancement processing unit 21 is composed of a density enhancement lookup table, and in the case of 16-bit image data, the portion to be observed is selected and the contrast is emphasized in that range, so that an easy-to-see image can be obtained. . By the above image processing, the micro domain structure of the magnetic material, which is the micro domain structure observation sample, can be clearly observed with a large magnification. The real-time TV image processing apparatus used in the present invention must be capable of performing image processing of at least 25 frames per second, preferably 30 frames per second. Example Using the apparatus shown in FIGS. 1 and 2, a 100 W ultra-high pressure mercury lamp was used as a light source 1, and a linear polarization of 480 mμ to 550 mμ obtained by using a filter 5 was used to obtain an objective lens 8 with a magnification of 20 times. The light is incident on one side not including the central axis of, parallel to the central axis. A hard floppy disk having a diameter of 130 mm was installed as the sample 10 for observing the magnetic domain structure in the minute region on the sample table 9 in FIG. 1, and a strong magnetic field of 3 KOe was generated in the electromagnet 11 for this sample, or the magnetic field was not generated as described above. The polarized light emitted from the objective lens 8 is incident at an angle of about 45 ° and irradiated at a reflection angle. The polarized light reflected by the sample 10 for observing the minute domain structure is passed through the objective lens 8, the analyzer 12, the pinhole 3 ', and the eyepiece 13 having a magnification of 10 times in parallel with the central axis without including the central axis, and then the T1- 26 A CCD camera (trade name, manufactured by NEC Corporation) 14-1 reaches the light receiving part. The video signal from the CCD camera light receiving section is sent to the camera control section, and as a digitized image signal current, it is A / D converted via the video switching section 16 of the real-time TV image processing device image Σ (product name of Nippon Avionics Co., Ltd.). It is input to the section 17. Here, the A / D conversion unit 17 is configured as 8 bits / pixel, the pixel configuration is 680 × 480 pixels / screen by using 64K D-RAM, and the integration result obtained by inputting and integrating the background image is 16 bits / pixel. , Integration time 33 msec / screen (8.3 seconds / 256 screens). Furthermore, as dynamic noise removal for background-removed images, However, L: input image, B: background image, S: input image-background image, K: weighting coefficient (K = 2, 4, 6, 8, 16 bits), M: image memory (640 × 480 × 16 bits) ), N: Calculated as the number of images. The static noise removal for the background removed image is calculated as follows. However, L, B, S, M, and n have the same meanings as described above. In addition, when the brightness enhancement effective data is displayed in full scale, the D / A conversion unit is configured with 256 gradations and 8 bits / pixel. After all, as an image processing method, a magnetic domain pattern in a saturation state in one direction is integrated to form a background image, the difference from the live image is taken for enhancement, and then averaging is performed. It has become possible. As a result, it was possible to observe a clear striped micro-domain structure with a magnification of 500 times. Action As described above, the present invention makes the emitted polarized light incident on the one side not including the central axis of the objective lens and perpendicularly to the objective lens, and the emitted light is applied to the magnetic material as the sample for observing the micro domain structure. The projected light and its reflected light are incident on the other side of the same objective lens that does not include the central axis and are used. Normally, a magnetic field of ± 0.1 KOe to 10 KOe or a strong magnetic field of ± 0.1 KOe to 10 KOe or 0.1 K Gauss to 10 KG auss is provided near or near the magnetic material, which is a sample for observing the magnetic domain structure in a minute region, especially in the vicinity thereof. Since a core coil (electromagnet) is installed as a means for applying a strong magnetic field capable of generating a high magnetic flux density, the polarized light is obliquely incident on the conventional magnetic domain structure observation sample. Unlike the device, the device of the present invention does not include the central axis of the objective lens in the polarized light, but the polarized light is incident parallel to the central axis of the objective lens, projected on the sample for observation of the micro domain structure, and the reflected light is the same. Since the apparatus is such that the central axis of the objective lens is not included and the light is emitted parallel to the central axis on the other side, it is possible to use an objective lens having a short focal length, that is, a large magnifying power. Further, the polarized light used for observing a magnetic material, which is a sample for observing a minute domain structure by the device of the present invention, is such that it does not include the central axis of the objective lens and is passed in parallel to the central axis. Preferably, when projecting onto a sample for observing a micro domain structure, the micro domain structure is observed and reflected with an incident angle and a reflection angle of about 45 ° with respect to the central axis of the objective lens. It is possible to observe the micro domain structure even when the sample magnetic material is magnetized not only in the direction perpendicular to the plane but also in the horizontal (in-plane) direction. Is. When the sample for observing the magnetic domain structure in a minute region is a magnetic hard material, a strong magnetic field is usually applied for observation, but a CCD camera and a real-time TV image processing device are used as an observation means of emission polarization. As a result, even if a strong magnetic field is applied, the background noise can be removed and the fine domain structure can be observed. Further, when the device of the present invention is used, an iron core coil (electromagnet) is used as a strong magnetic field applying means constituting the device, but by making the shape of the iron core as described above, There is a sufficient margin for mounting the structure observation sample. Effect Conventionally, in the observation of the magnetic domain structure of the magnetic material, only the magnifying power of about 1 to 4 times was obtained by the objective lens, but by using the device of the present invention, the magnifying power of 1 to 40 time can be obtained by the objective lens. As a result, it was possible to observe the magnetic domain structure of the magnetic material in the micro region at an expansion rate of 1 to 400 times by direct observation and 2.5 to 1000 times by image processing observation as a whole. For the first time, it has become possible to observe the magnetic domain structure in the minute region with dramatically high accuracy. Further, by using the device of the present invention, not only the perpendicular magnetic recording material but also the horizontal (in-plane) magnetic recording material can be observed for the micro domain structure. Further, when using the device of the present invention, when a specially shaped iron core is used in the iron core coil (electromagnet) as a strong magnetic field applying means, the sample for micro domain structure observation has a size of about 3 mm to 300 mm square or φ. In that case, it is possible to observe the magnetic domain structure in a minute region of an arbitrary portion without breaking or breaking, and the advantage thereof is extremely large.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a magnetic Kerr effect observing means in a microscopic domain structure observing means of the present invention, and FIG. 2 is a means for applying a strong magnetic field. It is an explanatory example figure of the shape of the iron core of the iron core coil (electromagnet) for strong magnetic field generation shown in FIG. FIG. 3 shows C as a means for observing the micro domain structure of the present invention.
FIG. 4 is a block diagram of a CD camera and a real-time TV image processing unit, and FIG. 4 is a flowchart diagram of the real-time TV image processing unit.

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[Procedure amendment] [Date of submission] September 24, 1993 [Procedure amendment 2] [Document name for amendment] Specification [Item name for amendment] Brief explanation of drawings [Amendment method] Change [Amendment content] [ BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram of a magnetic Kerr effect observing means in a microscopic domain domain structure observing means of the present invention. FIG. 2 is an explanatory diagram showing the shape of the iron core of the strong magnetic field generating iron core coil (electromagnet) shown in FIG. 1 as a means capable of applying a strong magnetic field. FIG. 3 CC as a means for observing the micro domain structure of the present invention
It is a block explanatory view of a D camera and a real-time TV image processing unit. FIG. 4 is a flowchart diagram of the real-time TV image processing unit.

Claims (1)

[Scope of utility model registration request] 1. In the magnetic Kerr effect measuring means, the light from the light source is emitted through the polarizer, and the emitted polarized light is incident on the one side not including the central axis of the objective lens and perpendicularly to the objective lens, and the emitted light is required. Accordingly, a means capable of applying a strong magnetic field is projected onto a sample for observing a micro domain structure, which is provided in the vicinity of the means, and the reflected light is again made incident on the other side not including the central axis of the same objective lens, and the emitted light An apparatus for observing a magnetic domain structure in a minute region, characterized in that polarized light which is emitted through an analyzer is observed. 2. Means capable of applying a strong magnetic field as necessary is ± 0.1 KOe or more, preferably ± 1 KOe to ± 10 K.
The micro domain structure observing device according to claim 1, which is means for providing an iron core coil capable of generating a strong magnetic field of Oe. 3. The iron core for an electromagnet as a means for applying a strong magnetic field provided in the vicinity of the sample for observing the micro domain structure is characterized in that it has a structure having an air gap portion used in the vicinity of the sample for observing the micro domain structure. Micro domain magnetic domain structure observing device according to claim 1 or claim 2 of the new patent registration. 4. The micro domain magnetic domain structure observation sample is a non-destructive sample having a size of 3 mm to 300 mm square or φ, and the micro domain magnetic domain according to any one of claims 1 to 3. Structure observation device. 5. The means for observing the polarized light which passes through the analyzer and emits the light is a means for visual observation through a eyepiece or a means for taking a photograph, and the minute model according to any one of claims 1 to 4 Magnetic domain structure observation device. 6. The means for observing the polarized light passing through the analyzer and emitting the polarized light is a means using a combination of an electron beam image pickup tube camera and a monitor TV, as claimed in any one of claims 1 to 4. Microscopic domain structure observation device described. 7. The means for observing the polarized light that passes through the analyzer and exits is C
The micro domain structure observing device according to any one of claims 1 to 4, characterized in that it comprises a CD camera and a real-time TV image processing means.