JP2010203989A - Magnetism observation microscope and method of observing magnetic domain - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic domain observation microscope efficiently and visibly observing the direction of the magnetization vector of a magnetic domain formed in a magnetic material. <P>SOLUTION: The magnetic domain observation microscope 1 includes an XY stage 3 and a rotary stage 4 for placing an observation target W having a magnetic domain and an optical system 10 is arranged at an upper portion of the observation target W. The optical system 10 is configured to emit light of linearly polarized light, and includes an image capturing apparatus for taking in light to be generated when linearly polarized light is reflected by the observation target W. Furthermore, the magnetic domain observation microscope 1 includes, as a control system 12, a CPU 31, and a gray scale magnetic domain image generation section 33 for generating a gray scale magnetic domain image, and a color magnetic domain image generation section 34 for generating a color magnetic domain image from the gray scale magnetic domain image. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a magnetic domain observation microscope and a magnetic domain observation method.

  It has become clear that the magnetic domain structure of the magnetic shield that shields the external magnetic field affects the characteristics of the read head in the head element used for writing information to the magnetic disk and reading information from the magnetic disk. Yes. Therefore, when developing or manufacturing a magnetic disk head element, the in-plane magnetic domain structure of the magnetic shield is evaluated using a magnetic domain observation microscope.

  The magnetic domain observation microscope has a configuration in which the magnetic domain structure of the observation object is observed by imaging the reflected light of the light irradiated on the observation object through an analyzer using the magneto-optic Kerr effect. The magneto-optic Kerr effect is a phenomenon in which when linearly polarized light is incident on an observation object having magnetism, it is reflected as elliptically polarized light whose principal axis is inclined from the direction of incident linearly polarized light according to its magnetization. Say.

  Here, the conventional magnetic domain observation microscope is configured such that when linearly polarized light is incident on an observation object, only a component parallel to the linearly polarized light is observed in the magnetization vector at the irradiation position. There is something. In the magnetic domain observation microscope having such a configuration, when the magnetization vector and the polarization direction are parallel to each other, a large difference in luminance from the nonmagnetic region can be imaged.

  However, in a magnetic domain in which the magnetization vector and the polarization direction are perpendicular to each other, since the magnetization vector has no component parallel to the polarization direction, it is observed as the same luminance as the nonmagnetic region. Furthermore, the left and right magnetization vectors having line symmetry with respect to the polarization direction of the incident light, that is, the same inclination angle with respect to the polarization direction, have the same inclination with respect to the polarization direction, and thus are imaged with the same luminance. For this reason, in the case of a complicated magnetic body shape or magnetic domain structure, it is difficult to estimate the magnetic domain structure.

  On the other hand, a magnetic domain observation microscope has been developed that has a configuration in which a plurality of incident systems and imaging systems are arranged so that an observation object having magnetic domains with different magnetization vector directions can be observed. In such a magnetic domain observation microscope, by acquiring a plurality of magnetic domain images while selecting an incident system and an imaging system, a plurality of magnetic domain images having different imaging directions can be obtained as a result. The magnetization direction of the observation object is specified from the plurality of magnetic domain images.

  In addition, a magnetic domain observation microscope has been developed in which an angle formed by an incident system and an imaging system and an observation object can be changed. In this magnetic domain observation microscope, a plurality of magnetic domain images are acquired while continuously changing the observation direction, and data analysis of these magnetic domain images is performed by a computer to identify the in-plane magnetization direction of the observation object.

JP 63-104015 A JP-A-6-236586 JP-A-5-215828 JP-A-5-333128

However, in the magnetic domain observation microscope having a plurality of incident systems and imaging systems, the structure of the apparatus is very complicated.
Further, in a magnetic domain observation microscope that relatively rotates an observation object, if the rotation angle of the observation object is set at two positions of 0 ° and 90 °, the direction and magnitude of the magnetization vector can be specified theoretically. Is possible. However, since the rotation of the polarization plane due to the magneto-optic Kerr effect is very small, a sufficient contrast may not be obtained.

On the other hand, if the rotation angle for observation with a magnetic domain observation microscope that relatively rotates the observation object is increased, sufficient contrast can be obtained and the magnetic domain structure can be observed in detail. However, the increase in the number of observation points has a problem that the observation time becomes longer and the amount of data becomes enormous.
Furthermore, in the conventional magnetic domain observation microscope, since the reflected light of linearly polarized light is imaged through the analyzer, only a gray scale magnetic domain image can be obtained. For this reason, the difference in the direction of the magnetization vector is difficult to understand, and the visibility is poor.

  The objective of this invention is providing the magnetic domain observation microscope which can observe the direction of the magnetization vector of the magnetic domain formed in the magnetic body efficiently and with sufficient visibility.

  According to one aspect of the present application, the observation object having a magnetic domain is configured to be irradiated with light having linear polarization, and is obtained by the magneto-optic Kerr effect when the light having linear polarization is irradiated to the observation object. An optical system having an imaging device that captures the reflected light and outputs a signal, means for relatively rotating the direction of the linearly polarized light with respect to the observation object, and the observation object from the signal output from the imaging apparatus A gray scale magnetic domain image generating unit that forms a gray scale image that does not include color information as an image of the image, assigning a rotation angle when the gray scale image is acquired to a hue, and a gradation value of a pixel of the gray scale image A magnetic domain image generating unit that colors the grayscale image by converting the saturation or brightness of the pixel into a magnetic domain. Observation microscope is provided.

  Further, according to another aspect of the present application, the object to be observed is irradiated with light having linearly polarized light, the reflected light obtained by the magneto-optic Kerr effect is captured and a signal is output, and the linearly polarized light with respect to the object to be observed is output. Rotating the direction relatively, forming a grayscale image that does not include color information as an image of the observation object from the output signal, assigning a rotation angle to the hue when the grayscale image is acquired, A magnetic domain observation method is provided, wherein a color magnetic domain image for coloring the gray scale image is generated by converting a gradation value of a pixel of the gray scale image into a saturation or brightness of the pixel.

The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not intended to limit the invention.

  According to the present invention, since the magnetic domain image colored according to the direction of the magnetization vector of the observation object is created, it is easy to visually confirm the magnetic domain structure. Moreover, since the magnetic domain image colored according to the direction of the magnetization vector is created, the boundary of the magnetic domain becomes clear, so that the structure can be evaluated easily and accurately.

FIG. 1 is a diagram showing a configuration of a magnetic domain observation microscope according to the first embodiment of the present invention. FIG. 2 is a flowchart for explaining magnetic domain observation processing. FIG. 3 is a diagram illustrating a hue circle referred to when a magnetic domain image is colored. FIG. 4 is a diagram illustrating an example of an observation object and an example of a colored magnetic domain image. FIG. 5 is a diagram showing an example of a color magnetic domain image of the observation object shown in FIG. FIG. 6 is a diagram showing a configuration of a magnetic domain observation microscope according to the second embodiment of the present invention. FIG. 7 is a flowchart for explaining the magnetic domain observation process. FIG. 8 is a plan view showing an example of an observation object. FIG. 9 is a graph showing the rotation angle dependency of the score acquired when calculating the rotational symmetry angle. FIG. 10 is a plan view showing an example of the observation object. FIG. 11 is a diagram illustrating an example of a colored magnetic domain image of the observation object in FIG. 10 at a rotation angle of 0 °. FIG. 12 is a diagram illustrating an example of a colored magnetic domain image of the observation target in FIG. 10 at a rotation angle of 120 °. FIG. 13 is a diagram illustrating an example of a colored magnetic domain image of the observation target in FIG. 10 at a rotation angle of 240 °. FIG. 14 is a diagram illustrating an example of a color magnetic domain image obtained by adding the colored magnetic domain images of FIGS. 11 to 13. FIG. 15 is a plan view illustrating an example of an observation object. FIG. 16 is a color magnetic domain image of the observation object of FIG. FIG. 17 is a flowchart for explaining the magnetic domain observation process. FIG. 18 is a graph showing the relationship between the gradation value and the rotation angle. FIG. 19 is a graph showing the relationship between the gradation value and the rotation angle. FIG. 20 is a graph showing the relationship between the gradation value and the rotation angle.

  A preferred embodiment of the present invention will be described with reference to the drawings. In the drawings, similar components are given the same reference numerals.

(First embodiment)
A first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a schematic configuration of a magnetic domain observation microscope. In the magnetic domain observation microscope 1, an XY stage 3 is attached on a surface plate 2, and a rotary stage 4 is provided on the XY stage 3. An observation object W for observing the magnetic domain is placed on the rotary stage 4 and can be rotated in the XY plane. The XY stage 3 and the rotation stage 4 are provided as a rotation unit that rotates the relative relationship between the polarization direction of the incident light and the observation object W at at least two different angles.

  Further, an optical system 10 is disposed above the rotary stage 4. The optical system 10 includes a light source 21 that outputs incident light, and a polarizing element 22 and a beam splitter 23 are inserted in order on the optical path of the light source 21. The polarizing element 22 has a polarizing plate and is configured to be able to extract linearly polarized light in a specific direction from incident light. The beam splitter 23 folds incident light downward by 90 °. An objective lens 24 is disposed below the beam splitter 23 so as to be close to the observation object W.

An analyzer 25 and a condensing lens 26 are sequentially arranged on the optical path of light passing through the beam splitter 23 from the objective lens 24. The analyzer 25 has a polarizing plate and is configured to extract polarized light in a specific direction from incident light. As the condensing lens 26, a convex lens in which the lower side (observation object W side) swells is used. An imaging element of the imaging device 27 (output unit), for example, a CCD (Charge Coupled Device) is disposed at the focal point above the condenser lens 26.

  Thus, the magnetic domain observation microscope 1 includes an incident system 28 having a light source 21, a polarizing element 22, a beam splitter 23, and an objective lens 24, an objective lens 24, a beam splitter 23, an analyzer 25, a condenser lens 26, and The imaging system 29 having the imaging device 27 is provided one by one.

The magnetic domain observation microscope 1 has a control system 12 that controls the optical system 10 and performs data processing.
The control system 12 has a CPU (Central Processing Unit) 31 that controls the entire system. The CPU 31 is connected to a stage control unit 32, a gray scale magnetic domain image generation unit 33, and a color magnetic domain image generation unit 34, and is configured to process signals between them based on a program.
The stage control unit 32 has a configuration for outputting drive commands to the XY stage 3 and the rotary stage 4, whereby the optical system 10, that is, the horizontal position and rotation of the observation object W with respect to the polarization direction of incident light. Control the position.

The gray scale magnetic domain image forming unit 33 has a configuration in which a magnetic domain image of the observation object W is generated in gray scale in response to an output signal from the imaging device 27, and data can be stored in and read from the memory 35. It has become.
The color magnetic domain image generation unit 34 receives the magnetic domain data generated by the gray scale magnetic domain image generation unit 33, generates a color magnetic domain image corresponding to the gray scale gradation value and the rotation angle, and two or more rotation angles. Is configured to add images created from In addition, a display unit 36 is connected to the color magnetic domain image generation unit 34, and the magnetic domain image of the observation object W can be displayed in color. The color magnetic domain image generation unit 34 can store and read a colored magnetic domain image and a color magnetic domain image in the memory 35.

The configuration of the magnetic domain observation microscope 1 is not limited to that shown in FIG. For example, instead of the configuration in which the observation target W is moved by the XY stage 3 and the rotary stage 4, a configuration in which a plurality of incident systems 28 and imaging systems 29 of the optical system 10 are arranged may be used. In this case, by selecting the incident system 28 and the imaging system 29 from among a plurality, the magnetic domain is observed while relatively changing the angle formed by the direction of the linearly polarized light and the observation object W.
Further, the incident system 28 and the imaging system 29 of the optical system 10 may be configured to be rotatable, and the optical system 10 may be rotated relative to the observation object W.

  Further, a Z stage for adjusting the height of the observation object W may be provided on the surface plate 2. Furthermore, instead of the display unit 36 or in addition to the display unit 36, an output unit that outputs an image to a paper medium or a magnetic recording medium may be provided. Further, the control system 12 may be realized by causing a personal computer or a portable terminal device to execute a predetermined program.

Next, a magnetic domain evaluation method using the magnetic domain observation microscope 1 will be described.
First, the observation object W is placed on the rotary stage 4. The observation object W is desirably placed so that the center of gravity thereof coincides with the rotation center of the rotary stage 4.

After placing the observation object W, the CPU 31 determines a relative angle formed by the observation object W with respect to the direction of the incident system 28 and the imaging system 29, that is, the polarization direction and the imaging direction of the incident light, for example, 10 °. An 8-bit grayscale magnetic domain image is acquired while rotating from 0 ° to 360 ° in steps of 0 °. Note that the number of grayscale bits is not limited to 8 bits. As the number of bits increases, the resolution of the magnetic domain image increases, but the amount of data processing increases.

  More specifically, the magnetic domain observation microscope 1 performs processing according to the flowchart shown in FIG. That is, the observation object W is rotated relative to the polarization direction of incident light (step S111). At the start of observation, the observation object W is moved to a predetermined initial position. Next, for example, an 8-bit grayscale magnetic domain image is acquired as the magnetic domain image of the observation object W using the optical system 10 (step S112), and the acquired grayscale magnetic domain image is colored (step S113).

Here, in the magnetic domain observation microscope 1 of this embodiment, every time the angle is updated while rotating the relative angle (rotation angle) of the observation object W to a predetermined step angle, for example, 360 ° from the initial position in increments of 10 °. Acquire a grayscale magnetic domain image. Therefore, the CPU 31 determines whether or not a gray scale magnetic domain image has been created at each angle while rotating the observation object W through 360 ° via the stage control unit 32 (step S114). If the rotation has not ended (No in step S114), the rotation angle is increased by the increment angle (step S116), and the process returns to step S111. That is, the CPU 31 causes the rotary stage 4 to output a drive signal via the stage control unit 32. The drive signal here is a signal for rotating the rotary stage 4 at a predetermined step angle. Thereby, the angle of the observation object W, that is, the irradiation angle of the incident light with respect to the observation object W is relatively rotated by the step angle.
On the other hand, if the rotation has been completed (Yes in step S114), the magnetic domain images colored in step S113 are added to create a color magnetic domain image (step S115).

Here, acquisition of the grayscale magnetic domain image in step S112 will be described in more detail below.
The CPU 31 outputs light from the light source 21. This light is converted into linearly polarized light by the polarizing element 22 and then enters the beam splitter 23. The light reflected by the beam splitter 23 enters the observation object W through the objective lens 24. The reflected light generated when such light (incident light) is incident on the observation object W becomes circularly polarized light by the magneto-optic Kerr effect. The reflected light passes through the objective lens 24, the beep splitter 23, and the analyzer 25, is collected by the condenser lens 26, and is incident on the imaging element of the imaging device 27. Thereby, the imaging device 27 outputs an electrical signal corresponding to the amount of reflected light extracted according to the orientation of the polarizing plate of the analyzer 25.

The gray scale magnetic domain image forming unit 33 acquires the electrical signal output from the imaging device 27 in association with the position of the imaging device arranged in two dimensions of the imaging device 27. For example, when the non-magnetic region has an intermediate gradation value and the magnetization direction is the same as the incident light, the gradation value is greater than 128, and in the opposite direction, the gradation value is smaller than 128.
Then, the intensity of each electric signal is converted into an 8-bit gray scale, that is, a gradation value of 256, and the gradation value is assigned to the two-dimensional coordinates (x, y) corresponding to the position of the pixel of the image sensor. As a result, a grayscale two-dimensional image (grayscale magnetic domain image) of the magnetic domain of the observation object W is obtained. The gray scale magnetic domain image is stored in the memory 35 in association with the shape and rotation angle of the observation object W.

Next, the coloring of the gray scale magnetic domain image in step S113 will be described in detail below.
The grayscale magnetic domain image data is sent to the color magnetic domain image generation unit 34, and generation of a color magnetic domain image is started. For coloring the magnetic domain image, coordinates of the observation object W, information on the rotation angle, and magnetic domain contrast information, that is, gradation values are used.
The magnetic domain observation microscope 1 is colored using the HSV color space. Here, H represents a hue, and is represented by a numerical value with a rotation angle of 0 to 360 (degrees). S is a saturation value represented by a numerical value of 0 to 100 (%). V is lightness and is represented by a numerical value of 0 to 100 (%).

  The color magnetic domain image generation unit 34 converts the gradation value into saturation. The gray scale gradation value G (x, y) of the coordinate (x, y) of the magnetic domain image at the rotation angle φ is examined, and a value is assigned to each of H, S, and V as follows.

When G (x, y) ≧ 128, (H, S, V) = (φ, α × | G (x, y) −128 | / 256, 50)
When G (x, y) <128, (H, S, V) = (φ + 180, α × | G (x, y) −128 | / 256, 50)
And

  Here, the hue H is determined according to the rotation angle. For example, the hue circle as shown in FIG. 3 is extracted according to the hue value by extracting only those with saturation of 100, lightness of 50, and hue of 30 °. Each color is displayed in a hexadecimal color code. For example, the color code “# FF0000” is red (red), the color code “# 00FFFF” is light blue (aqua, cyan), and the color code “# FF00FF” is bright. The color code “# FFF00” indicates yellow (yellow), and the color code “# 00FF00” indicates lime color (fuchsia, magenta).

  For example, when the rotation angle φ is 0 ° in the initial state and the gradation value is 128 or more, the region is colored red (# FF0000). When the rotation angle φ is 0 ° and the gradation value is smaller than 128, the region is colored light blue (# 00FFFF). That is, the two colors arranged opposite to each other in the color code of FIG. 3 indicate that the directions of the magnetization vectors are 180 ° different. That is, the magnetic domain observation microscope 1 colors the magnetic domain image picked up every time the rotation angle φ is changed with a plurality of colors assigned to face each other. For this reason, a magnetic domain image colored with two hues with respect to one rotation angle is obtained.

  Saturation S is a value obtained by dividing an absolute value of a value obtained by subtracting 128 which is an intermediate gradation value from gradation value G (x, y) by 256 and multiplying by α. Here, 256 is a value corresponding to 256 gray scales of 8-bit gray scale. α is a parameter that determines the saturation after coloring in accordance with the contrast of the grayscale magnetic domain image.

  When vivid coloring is desired even with a weak magnetic domain contrast, α is set to a large value. Depending on the value of α, the value of S may exceed 100. In this case, a value of 100 or more is replaced with 100. In order to prevent saturation values from being saturated even in the presence of noise, for example, a distribution in which the gradation value G (x, y) of the actual magnetic domain image is 128 is examined in advance. It is preferable to select a value such that α is in the range of 71 to 100 when the degree S is about 100 to 140.

  By the way, in the magnetic domain image taken when the rotation angle φ is 0 °, the magnetization vector of the magnetic domain is parallel to the direction of the linearly polarized light of the incident light, and the direction of the magnetization vector is the same as the direction of the linearly polarized light. In this case, the hue H becomes the same value as red (# FF0000). Further, the value of the gradation value G (x, y) becomes the largest when the magnetization vector is parallel to and in the same direction as the direction of the linearly polarized light.

  On the other hand, when the direction of the magnetization vector of the magnetic domain is shifted by 30 ° with respect to the direction of linearly polarized light, the hue H becomes the same value as red (# FF0000), but the gradation value G (x, y ) Is smaller than when the value is parallel to the direction of linearly polarized light. For this reason, the saturation S is reduced and the color is relatively dark.

  When the direction of the magnetization vector of the magnetic domain is opposite to the direction of linearly polarized light, the gradation value G (x, y) is smaller than 128. For this reason, the hue H becomes the same value as the light blue (# 00FFFF) rotated by 180 °. Furthermore, in this case, since the direction of the magnetization vector is opposite to the direction of linearly polarized light, the gradation value G (x, y) is the smallest, but the absolute value | G (x, y) −128 | Since it becomes larger, the saturation S becomes the maximum and becomes the brightest. That is, in this case, it is colored lightest and brightest.

  On the other hand, when the magnetization vector is deviated by 150 ° with respect to the direction of linearly polarized light, the hue H becomes the same value as the light blue (# 00FFFF), but the gradation value G (x, y) is 180 °. Larger than In this case, the value of | G (x, y) −128 | is smaller than the value when it is shifted by 180 °, so that the saturation S becomes relatively dark.

  Further, when the magnetization vector is shifted by 90 ° with respect to the direction of linearly polarized light, the gradation value G (x, y) becomes 128, so the saturation S becomes 0 and gray (# 808080). Become.

  That is, as shown in FIG. 4A, assuming that the observation object W has a magnetic domain structure having magnetization vectors of 0 °, 30 °, 180 °, 150 °, and 90 °, the rotation angle is 0. When the image is taken at an angle, a colored magnetic domain image is obtained as shown in FIG. In each of the following drawings, color coding and saturation are shown by hatching instead of showing a diagram in which a magnetic domain image is colored. In the case where the magnetization vectors are in the same direction, the hatching lines have the same direction, and the greater the saturation, the higher the hatching line density.

  That is, the region R1, the magnetization vector of 0 °, the region R2, the region of 30 °, the region R3 of 180 °, the region R4 of 150 °, and the region R5 of 90 ° are respectively brightest red, relatively dark red, and lightest light blue. A relatively dark blue and non-colored image can be obtained.

  In this way, one magnetic domain image colored from each gradation value of each coordinate of one gray scale magnetic domain image is created. Here, since this magnetic domain observation microscope 1 performs observation at a step angle of 10 °, 36 gray-scale magnetic domain images and corresponding colored magnetic domain images are created and stored in the memory 35.

  For example, FIG. 4C shows a colored grace case image when the rotation angle φ is started from 0 ° and rotated three times at a step angle of 10 °. That is, since the rotation angle φ is 30 °, the magnetic domain image is colored with the “# FF8000” system and the “# 0080FF” system corresponding to 30 ° and 210 ° in FIG. In this case, since the region R2 is parallel to the rotation angle φ, the hue is the same value as “# FF8000” and is the brightest. Since the region R1 is shifted by 30 ° with respect to the rotation angle φ, the hue is the same value as “# FF8000” and becomes relatively dark. Since the region F5 is shifted by 60 ° with respect to the rotation angle φ, the hue is the same value as “# FF8000” and becomes the darkest. Since the region R3 is opposite and parallel to the rotation angle φ, the hue is the same value as “# 0080FF” and the brightest. Since the region R4 is opposite to the rotation angle φ and shifted by 30 °, the hue is the same value as “# 0080FF” and becomes relatively dark.

A color magnetic domain image is created in step S115 based on the plurality of colored magnetic domain images acquired while rotating the rotation angle from 0 ° to 360 ° in a plurality of steps. Here, FIG. 5 shows an example of a color magnetic domain image created for the observation object W in FIG. In this color magnetic domain image, the hue R and the saturation S of the region R1 are calculated based on the data of the plurality of colored magnetic domain image regions R1. In this case, since the magnetization vector of the region R1 is 0 °, the hue H has the same value as “# FF0000”. Hereinafter, the hues H of the region R2, the region R3, the region R4, and the region R5 are “# FF8000”, “# 00FFFF”, and “# 0080FF”, respectively.
And the same value as “# 8000FF”.

The created color magnetic domain image is displayed on the display unit 36. If the hue circle as shown in FIG. 3 is simultaneously displayed, the direction of the magnetization vector can be easily seen. In this case, it is preferable to display the actual color instead of or together with the hexadecimal color code. Here, in the hue circle shown in FIG. 3, the combination of the angle and the hue is arranged clockwise, but may be arranged counterclockwise.
The above processing is controlled by the CPU 31 based on a program stored in a storage unit (not shown).

As described above, in the magnetic domain observation microscope 1, the magnetic domain images are acquired at a plurality of rotation angles φ while changing the relative angle of the direction of linearly polarized light with respect to the observation object W. It becomes easy to make the direction of the vector and the linearly polarized light parallel. For this reason, the boundary of a magnetic domain can be clarified. Particularly, since the gray scale magnetic domain image is colored in association with the rotation angle φ, the direction of the magnetization vector of each magnetic domain can be easily specified by comparing with the hue ring, and the boundary of the magnetic domain is Become clear.
In the region where the magnetization vector of the magnetic domain and the direction of the linearly polarized light are not parallel, the saturation S is changed according to the magnitude of the component parallel to the direction of the linearly polarized light, so that the deviation from the direction of the linearly polarized light is colored. Thus, the direction of the magnetization vector can be distinguished with high accuracy.

  Here, a magnetic domain having a close hue means that the direction of the magnetization vector is close. Therefore, the direction of the magnetization vector can be specified by comparing with the hue ring as shown in FIG. 3, so that the magnetic domain structure is evaluated with high visibility. be able to.

  In this magnetic domain observation microscope 1, coloring is performed by changing the saturation S with the gradation value G (x, y) while keeping the brightness V constant. However, the brightness V is adjusted with the saturation S constant. You may color by changing by value G (x, y).

  In addition, each time a grayscale magnetic domain image is acquired, image data is stored in the memory 35, and after all grayscale magnetic domain images have been acquired, the color magnetic domain image generation unit 34 colors and adds each grayscale magnetic domain image, A color magnetic domain image may be created.

(Second Embodiment)
A second embodiment will be described in detail with reference to the drawings. In addition, the description which overlaps with 1st Embodiment is abbreviate | omitted.
FIG. 6 shows the configuration of the magnetic domain observation microscope. The CPU 31 is connected so that data from the gray scale magnetic domain generation unit 33 can be input and output, and also functions as a rotational symmetry angle calculation unit.

In FIG. 7, the flowchart of the process of the magnetic domain observation microscope 1 in this embodiment is shown.
First, the magnetic domain observation microscope 1 acquires an image of the observation object W placed on the rotation stage 4 in the same manner as in the first embodiment, and rotationally symmetric from the outline of the magnetic material of the observation object W. A corner is calculated (step S101).

  When calculating the rotational symmetry angle, the gray scale magnetic domain generation unit 33 first acquires a magnetic domain image when the relative angle between the direction of the incident system 28 and the direction of the imaging system 29 and the observation object W is 0 °. To do. Then, binarization is performed depending on whether or not the gradation value of each coordinate in the magnetic domain image is an intermediate gradation value. As a result, the magnetic body portion and the non-magnetic body portion of the observation object W are distinguished from each other, so that an outline of the magnetic body of the observation object W is obtained.

Thereafter, the observation object W is rotated by a predetermined step angle, for example, 10 ° to create a binary image a plurality of times. Then, pattern matching of each binarized image is performed on the basis of the binarized image having a relative angle of 0 ° acquired first, and a score such as similarity or dissimilarity is acquired, for example. The rotation angle at which the score is maximized or minimized is set as the rotational symmetry angle of the observation object W.

  For example, when the CPU 31 calculates a score for the observation object W1 having a rough shape in which two corners of three corners of an equilateral triangle as shown in FIG. 8 are dropped, the rotation as shown in FIG. Angular dependence was obtained. Thereby, the CPU 31 determines that 0 °, 120 °, and 240 ° at which the score is maximized are rotation symmetry angles of the general shape of the observation object W1.

  Next, the CPU 31 determines a step angle (step S102). In this case, since it is necessary to observe at three positions of 0 [deg.], 120 [deg.], And 240 [deg.] Which are rotational symmetry angles, the step angle is 120 [deg.].

  Thereafter, as shown in steps S111 to S115, as in the first embodiment, a gray scale magnetic domain image is acquired while rotating the observation object W according to the step angle, and a color magnetic domain image is created therefrom.

  For example, in the observation object W2 shown in FIG. 10, when the relative angle (rotation angle φ) is 0 °, a colored magnetic domain image G1 as shown in FIG. 11 is obtained. Since the magnetic domain image G1 has a relative angle of 0 °, the hue H is the color code “# FF0000” system corresponding to 0 ° and the color code “#” corresponding to 180 ° as shown in the hue circle of FIG. "00FFFF" series color.

  More specifically, since the direction of the magnetization vector of the region R11 is 0 °, the hue H is the same value as “# FF0000” and the saturation S is the maximum value. The regions R12 and R13 are not colored because the directions of the magnetization vectors are 270 ° and 90 °, respectively, and are orthogonal to the direction of linearly polarized light. In the region R14, the hue H is the same value as “# 00FFFF”, and the saturation S is the maximum value. The region R15 has a magnetization vector direction of 30 ° and is close to 0 °, so the hue H is # FF0000, but the saturation S is darkened by the amount deviated from 0 °. Similarly, since the region R16 has a magnetization vector direction of 300 °, the hue H has the same value as “# FF0000”, but the saturation S is darkened by the amount deviated from 0 °. Since the region R16 has a larger deviation from 0 ° than the region R15, the region R16 is darker.

Next, the magnetic domain observation microscope 1 acquires a gray scale magnetic domain image when the rotation angle φ is 120 ° according to a command from the CPU 31, and colors it with the color magnetic domain image generation unit 34.
FIG. 12 shows a magnetic domain image G2 when the relative angle (rotation angle φ) is 120 °. This figure is shown in the same orientation as FIG. 11 for easy understanding.

Since the magnetic domain image G2 is an image acquired when the relative angle is 0 °, the hue H corresponds to the color code “# 00FF00” system corresponding to 120 ° and 300 ° as shown in the hue circle of FIG. It is colored in the color code “# FF00FF” series.
Since the region R13 and the region R14 are relatively close to 120 °, the hue H has the same value as “# 00FF00”. Since the region R14 is closer to 120 °, it is colored relatively brighter than the region R13.

  In addition, since the region R11, the region R12, and the region R16 are relatively close to 300 °, the hue H has the same value as “# FF00FF”. The region R16 is most brightly colored because the direction of the magnetization vector is 300 ° and is equal to the direction of linearly polarized light of the incident light. Hereinafter, the color is brightly colored in the order close to 300 °, that is, in the order of the region R12 and the region R11. The region R15 is not colored because the direction of the magnetization vector is orthogonal to the direction of linearly polarized light of the incident light.

Further, the magnetic domain observation microscope 1 acquires a gray scale magnetic domain image when the rotation angle φ is 240 ° according to a command from the CPU 31, and colors it with the color magnetic domain image generation unit 34.
FIG. 13 shows a magnetic domain image G3 when the relative angle (rotation angle φ) is 240 °. This figure is shown in the same orientation as FIG. 11 for easy understanding.

Since the magnetic domain image G3 is an image acquired when the relative angle is 0 °, the hue H corresponds to the color code “# 0000FF” system corresponding to 240 ° and 60 ° as shown in the hue circle of FIG. It is colored in the color code “# FFFF00” series.
Since the region R12, the region R14, and the region R16 are relatively close to 240 °, the hue H has the same value as “# 0000FF”. The region R12 closest to 240 ° is most brightly colored. The region R14 and the region R16 are colored with the same brightness because the angle of deviation from 240 ° is the same.

  Further, since the region R11, the region R13, and the region R15 are relatively close to 60 °, the hue H has the same value as “# FFFF00”. The region R13 and the region R15 are colored with the same brightness because the deviation angle from 60 ° is equal. The region R11 has the largest deviation angle from 60 °, and thus is darker than the regions R13 and R15.

When three images are added, a color magnetic domain image G4 as shown in FIG. 14 is obtained.
As described above, the region R11 and the region R14 are colored with the color codes “# FF0000” and “# 00FFFF”, respectively.
The region R12 is colored with a hue corresponding to 270 °, that is, the color code “# 8000FF”, by adding the information in FIGS. Similarly, the region R13 is colored with a hue corresponding to 90 °, that is, the color code “# 80FF00”, by adding the information of FIG. 12 and FIG.
The region R15 is colored with the color code “# FF80000” as a result of adding the information of FIG. 11 to FIG. Similarly, the region R16 is colored with the color code “# FF00FF” as a result of adding the information of FIG. 11 to FIG.

As described above, the magnetic domain observation microscope 1 is configured to determine the relative angle of the direction of linearly polarized light with respect to the observation object W by paying attention to the rotational symmetry of the outline of the magnetic material of the observation object W2. As a result, the observation time can be reduced. The effect of creating a color magnetic domain image is the same as that of the first embodiment.
Here, it is known that the magnetic domain structure of the magnetic body is limited to some extent by the outline of the magnetic body, and is often close to the rotational symmetry angle of the outline of the magnetic body. Therefore, by calculating the rotational symmetry angle, it becomes easy to make the magnetization vector of each magnetic domain parallel to the direction of the linearly polarized light of the incident light. Since the error can be reduced by making the direction of the linearly polarized light of the incident light as parallel as possible to the direction of the magnetization vector, the magnetic domain structure can be evaluated efficiently and accurately.

  In the above description, it is assumed that the observation object W2 is installed with good symmetry of the outline, but the magnetic domains may be arranged at an arbitrary angle. In that case, first, a magnetic domain image is acquired at that angle, and a binarization process is performed to determine whether or not it is an intermediate gradation value, thereby obtaining an outline of the magnetic body of the observation object W. Further, the Hough transform is performed on the point group obtained by performing the edge extraction by the processing of the CPU 31. Thus, the longest side of the sides constituting the outline of the magnetic material can be linearly approximated, and the angle (relative angle) formed by this straight line and the direction of the linearly polarized light of the incident light is set as the reference angle. Here, the relative angle is an angle of linearly polarized light when the optical system is rotated, and is a rotation angle when the observation object W is rotated.

(Third embodiment)
A third embodiment will be described in detail with reference to the drawings. In addition, the description which overlaps with each said embodiment is abbreviate | omitted.

  The configuration of the magnetic domain observation microscope is the same as that shown in FIG. The CPU 31 is connected so that data from the gray scale magnetic domain generation unit 33 can be input and output, and also functions as an imaging angle calculation unit.

First, as in the second embodiment, the rotational symmetry angle of the approximate shape of the magnetic body of the observation object W is calculated.
Next, a magnetic domain image is captured and colored by limiting the relative angle between the observation object W and the directions of the incident system 28 and the imaging system 29 to the rotational symmetry angle obtained above and the intermediate angle. Then, all the images are added to generate one color magnetic domain image.

  Here, when the rectangular magnetic body as shown in FIG. 15 is the observation object W2, the rotational symmetry angles are 0 ° and 180 °, but the directions of the incident system 28 and the imaging system 29, and the observation object The relative angle with W2 is set to 0 °, 90 °, 180 °, and 270 ° including the intermediate angle, and a gray scale magnetic domain image is captured at each rotation angle φ.

  Here, when the direction parallel to the magnetization vectors of the region R21 and the region R22 is set to 0 ° (initial value) and only the rotational symmetry angle of the observation object W2 is set to the rotation angle φ, the region R21 and the region R22 are set. Can be colored because the magnetization vector is parallel to the linearly polarized light of the incident light and the direction of the imaging system 29. However, since the magnetization vectors of the region R23 and the region R24 are orthogonal to the linearly polarized light of the incident light and the direction of the imaging system 29, the gradation value necessary for coloring cannot be obtained. Similarly, when the direction parallel to the magnetization vectors of the region R23 and the region R24 is set to 0 ° and only the rotational symmetry angle is set to the rotation angle φ, the gradation value necessary for coloring the region 21 and the region R22 cannot be obtained. .

  On the other hand, by obtaining a grayscale magnetic domain image even at an intermediate angle, the regions R21 to R24 can be colored as shown in FIG. Furthermore, since the number of locations where the magnetic domain observation is performed is increased, the image is easily captured so that the angle formed by the magnetization vector and the linearly polarized light becomes small, so that the boundary between the magnetic domains becomes clear.

As described above, the magnetic domain observation microscope 1 is configured to select the rotational symmetry angle of the approximate shape of the magnetic material and the intermediate angle thereof as the relative angle of the direction of the linearly polarized light with respect to the observation object W. , Can reduce the observation time. Since more rotation angles are employed than when only the rotational symmetry angle is selected, the measurement error can be reduced. The effect of creating a color magnetic domain image is the same as that of the first embodiment.
Note that the processing when the observation object is arranged at an arbitrary angle is the same as in the second embodiment.

(Fourth embodiment)
The fourth embodiment will be described in detail with reference to the drawings. The configuration of the magnetic domain observation microscope is the same as that shown in FIG. The CPU 31 is connected so that data from the gray scale magnetic domain generation unit 33 can be input and output, and also functions as an approximate straight line calculation unit and an imaging angle calculation unit.

  First, as in the second embodiment, the rough shape of the magnetic body of the observation object W is obtained by binarization processing, and the sides constituting the rough shape are linearly approximated. As a method of linear approximation, for example, the CPU 31 performs a Hough transform after obtaining a group of points that form sides by edge extraction. Then, by calculating the angle formed between the approximate straight line obtained by the Hough transform and, for example, the horizontal direction, the angle formed by each side of the outline of the magnetic material can be calculated.

Next, the CPU 31 limits the relative angle between the observation object W and the direction of the incident system 28 and the imaging system 29 to an angle formed by each side of the outline of the magnetic body obtained above, that is, each side and the incident side. The rotation angle φ is set so that the direction of linearly polarized light is parallel. For example, when the observation object W has the structure shown in FIG. 15, two orthogonal sides are extracted, and therefore, the angles parallel to each side, 0 °, 90 °, 180 °, and 270 ° are rotation angles. Selected as φ.
Then, a gray scale magnetic domain image is acquired at each rotation angle φ and colored. Then, all the magnetic domain images are added to generate one color magnetic domain image. The processing here is the same as the processing described in the first embodiment or the second embodiment.

  As described above, in this magnetic domain observation microscope 1, since the relative angle of the direction of linearly polarized light with respect to the observation object W is limited to an angle substantially parallel to the side of the outline of the magnetic material, the observation time is reduced. Is done. In particular, since the observation is performed at an angle parallel to the side forming the outline of the magnetic material, the error can be reduced, and the magnetic domain structure can be evaluated efficiently and accurately. The effect of creating a color magnetic domain image is the same as that of the first embodiment.

(Fifth embodiment)
A fifth embodiment will be described in detail with reference to the drawings. In addition, the description which overlaps with each said embodiment is abbreviate | omitted. The configuration of the magnetic domain observation microscope is the same as that shown in FIG. The CPU 31 is connected so that data from the gray scale magnetic domain generation unit 33 can be input and output, and also functions as an imaging angle calculation unit.

  In FIG. 17, the flowchart of the process of the magnetic domain observation microscope 1 in this embodiment is shown. From step S101 to step S113, processing similar to that of the second embodiment is performed. The processing so far is performed until acquisition of the magnetic domain image at the planned rotation angle φ is completed (steps S114 and S115).

Next, the rotation angle dependency of the gradation value of each pixel is calculated (step S121).
First, the relationship between the gradation value G (Pi) and the rotation angle φ is obtained at all points Pi (i is an arbitrary integer) inside the magnetic body in each magnetic domain image. Thereby, for example, a graph as shown in FIG. 18 is obtained. The horizontal axis of the graph indicates the rotation angle φ, and the vertical axis indicates the gradation value. As an example, FIG. 18 shows two measurement results, that is, a gradation value G (P1) of a point P1 that is a predetermined position in the observation object W, and a gradation value G (P2) of a point P2 that is also a predetermined position. Only) is shown. Then, the CPU 31 calculates differences ΔG (P1) and ΔG (P2) between the maximum and minimum gradation values at the points P1 and P2. Then, the minimum value ΔGMin at each point P1, P2 is calculated.

  Thereafter, the CPU 31 determines whether the step angle is appropriate (step S122). Specifically, the CPU 31 checks the magnitude of the preset threshold value and ΔGMin. When ΔGMin is larger than the threshold, it is determined that the magnetization vector and the direction of the linearly polarized light of the incident light are substantially parallel at all points inside the magnetic body, and the step angle is determined to be appropriate (step S122). Yes). That is, in this case, it is considered that the direction of the magnetization vector can be specified with high accuracy by acquiring a magnetic domain image at each rotation angle φ at this step angle. Therefore, each of the grayscale magnetic domain images acquired by the processing so far is colored by the same processing as in the first embodiment (step S123). Further, the colored magnetic domain images are added to create one color magnetic domain image (step S124).

  On the other hand, when ΔGMin is equal to or smaller than the threshold value, it is determined that the imaging is performed under the condition that the magnetization vector and the direction of the linearly polarized light of the incident light are difficult to be parallel. That is, the CPU 31 determines that the accuracy of specifying the direction of the magnetization vector is lowered when the magnetic domain observation is performed under this condition, and determines that the step angle is not appropriate (No in step S122).

  In this case, the CPU 31 decreases the step angle of the relative angle between the direction of the incident system 28 and the imaging system 29 and the observation object W (step S125). To reduce the step angle, for example, an intermediate angle is added to the initially set rotation angle φ. Further, a rotation angle corresponding to an angle obtained by dividing the rotation angle φ between the two rotation angles φ arranged in order into three or four may be added.

Thereafter, the process returns to step S102, and a grayscale magnetic domain image is acquired at the reset rotation angle φ. Thereafter, the processing from step S102 to step S122 and step S125 is repeated until ΔGMin becomes larger than the threshold value.
Then, using each magnetic domain image acquired at the rotation angle φ when ΔGMin is larger than the threshold value, the color magnetic domain generation unit 34 creates a color magnetic domain image by the same method as in the first embodiment.

  Here, the process of step S122 and step S123 will be described in more detail with a specific example. In addition, as a magnetic body of the observation object W, a rough shape in which rotational symmetry angles of 0 °, 90 °, 180 °, and 270 ° are calculated is assumed. Then, the relationship between the gradation value and the rotation angle at the points P1 and P2 inside the magnetic body of the observation object W having such a rotational symmetry angle is a curve as shown in FIG. It is assumed that the phase difference is 45 degrees).

When the initial condition of the magnetic domain observation in the magnetic domain observation microscope 1 is such that the gradation values at the magnetic domain image points P1 and P2 are such that four plots as shown in FIG. 18 are obtained, ΔG (P1) = 40 , ΔG (P2) = 28.28. The minimum value of ΔG (Pi) is ΔGMin = ΔG (P2) = 28.28.
Here, for example, when “35” is set as the threshold value of ΔGMin in the CPU 31, “28.28”, which is the value of ΔGMin, is smaller than the threshold value. For this reason, the CPU 31 determines that the step angle needs to be reduced.

  For example, when the CPU 31 is programmed to add the intermediate angle to the rotation angle φ as described above, the rotation angle φ is 0 °, 45 °, 90 °, 135 °, 180 °, 225 °, 270 °, Eight of 315 ° are set as new rotation angles φ. In this case, the step angle is changed from the initial condition of 90 ° to 45 °.

  Then, when a gray scale magnetic domain image is acquired at these eight rotation angles φ, for example, a plot as shown in FIG. 20 is obtained. In FIG. 20, the gradation value at points P1 and P2 is ΔG (P1) = ΔG (P2) = 40, and this value becomes ΔGMin. That is, ΔGMin can be made larger than the threshold value under the condition of the step angle.

  As a result, the CPU 31 performs magnetic domain observation at these eight rotation angles φ and creates a color magnetic domain image. In addition, it is preferable to calculate points other than the points P1 and P2 from the viewpoint of improving the accuracy of the evaluation of the step angle, that is, the accuracy of the magnetic domain observation. However, even when the evaluation is performed using only these two points, Accuracy can be increased. That is, it is possible to arbitrarily set the number of points Pi to which attention is paid when the step angle is evaluated.

  As described above, the magnetic domain observation microscope 1 evaluates whether the step angle (rotation angle φ) is appropriate, and if not, sets the step of the rotation angle φ to be smaller. Information sufficient for visualization of a magnetic domain image can be obtained. Since the number of rotation angles φ for acquiring the magnetic domain image can be optimized, the time required for colorizing the magnetic domain image can be reduced. The effect of creating a color magnetic domain image is the same as that of the first embodiment.

The industrial applicability of the magnetic domain observation microscope 1 in each of the above embodiments includes, for example, observation of a magnetic domain structure in a magnetic material or a superconducting material. In particular, ferromagnetic materials are used in energy conversion devices called power magnetics such as magnetic memory (MRAM), magnetic sensors, magnetic actuators, and motors for electric vehicles in addition to hard disks, and are used in those fields. Can be assumed.

Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations, conditions, and the like described in the embodiments, and various modifications can be made. For example, as a method of linear approximation of each side of the magnetic body in the fourth embodiment, a least square method may be used for the edge point group.
In addition, as a method for evaluating the suitability of the step angle of the rotation angle φ in the fifth embodiment, the standard deviation of ΔG (Pi) at all points inside the magnetic body is calculated, and is larger than a preset threshold value. You may determine with a small thing that it is appropriate.

  All examples and conditional expressions given here are intended to help the reader understand the inventions and concepts that have contributed to the promotion of technology, such examples and It should be construed without being limited to the conditions, and the organization of such examples in the specification is not related to showing the superiority or inferiority of the present invention. Although embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions and variations can be made thereto without departing from the spirit and scope of the present invention.

1 Magnetic domain observation microscope 3 XY stage (rotating part)
4 Rotating stage (rotating part)
10 Optical System 27 Imaging Device (Output Unit)
31 CPU
32 Stage control unit 33 Gray scale magnetic domain image generation unit 34 Color magnetic domain image generation unit W, W1, W2, W3 Observation object

Claims (6)

A light source that emits light having linearly polarized light;
An output unit that captures reflected light obtained by the magneto-optic Kerr effect when the light source illuminates the observation object; and outputs a signal;
A rotating unit that rotates the direction of the linearly polarized light relative to the observation object;
A grayscale magnetic domain image generation unit that forms a grayscale image that does not include color information as an image of the observation object from the output signal;
A color magnetic domain image that colors the grayscale image by assigning a rotation angle when obtaining the grayscale image to a hue, and converting a gradation value of a pixel of the grayscale image into a saturation or brightness of the pixel A generator,
A magnetic domain observation microscope comprising:   The color magnetic domain image generation unit has data in which a rotation angle and a hue are associated with each other, and when the gradation value of the pixel is equal to or higher than an intermediate gradation value, the rotation angle at that time is assigned to the hue, and the gradation value of the pixel 2. The magnetic domain observation microscope according to claim 1, wherein an angle obtained by adding 180 ° to a rotation angle at that time is assigned to a hue when is smaller than an intermediate gradation value.   The saturation or brightness of the pixel is configured to be proportional to the absolute value of the difference between the intermediate gradation value and the gradation value of the pixel when the non-magnetic region is set to the intermediate gradation value. The magnetic domain observation microscope according to claim 1 or 2.   The magnetic domain observation microscope according to any one of claims 1 to 3, wherein a rotational symmetry angle of the observation object is selected as a rotation angle for acquiring the gray scale image.   A change in gradation value of a plurality of gray scale image pixels acquired while relatively rotating the observation object is examined, and a difference between the maximum value and the minimum value of the gradation values of the same pixel is smaller than a preset threshold value. The magnetic domain observation microscope according to claim 1 or 2, characterized in that the number of rotation angles is sometimes increased. Irradiate light with linearly polarized light on the observation object, capture the reflected light obtained by the magneto-optic Kerr effect, and output a signal,
Rotating the direction of the linearly polarized light relative to the object to be observed;
Forming a grayscale image containing no color information as an image of the observation object from the output signal;
A color magnetic domain image for coloring the grayscale image by assigning a rotation angle when obtaining the grayscale image to a hue and converting a gradation value of a pixel of the grayscale image into a saturation or brightness of the pixel. Magnetic domain observation method characterized by generating.

Images