JP2013205400A - Magnetic property measuring device, magnetic property measuring method, and magnetic field measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for providing an image representing a state of magnetization while separating an in-plane magnetization component and a vertical magnetization component.SOLUTION: In a magnetic property measuring device that measures magnetization by using a Kerr effect, a first image is obtained by making incident light incident at a specific angle of incidence, and a second image is obtained by reversing a direction of incidence. A calculation device calculates a difference image between the first image and the second image, and an added image of the first image and the second image. The difference image is an image that represents an in-plane magnetization component at respective parts of a sample, and the added image is an image that represents a vertical magnetization component at respective parts of a sample.

Description

  The present invention relates to a magnetic property measuring apparatus, a magnetic property measuring method, and a magnetic field measuring method, and in particular, for measuring a magnetic property of a substance or a magnetic field at a specific position in space using a magneto-optical effect such as a Kerr effect or a Faraday effect. Regarding technology.

  Measuring the magnetization state of an object is one of the interesting problems in science and technology. For example, scientifically and technically useful knowledge can be obtained by specifying the structure of the magnetic domain of a magnetic material used for an electromagnetic steel plate or a magnetic disk head.

  As one of the methods for measuring the magnetization state of one object, a technique is known in which linearly polarized incident light is incident on a magnetic material and the magnetization state is obtained from rotation of the plane of polarization due to the Kerr effect in the magnetic material (for example, Patent Document 1). Since the rotation angle of the polarization plane is generally proportional to the magnetization magnitude of the sample, the magnetization magnitude can be calculated from the rotation angle of the polarization plane. Further, if an image is obtained in which each pixel has luminance depending on the rotation angle of the polarization plane using the polarizing plate, the image becomes an image representing the state of magnetization at each position of the sample.

  FIG. 1 is a diagram illustrating rotation of a polarization plane when probe light is incident. The in-plane magnetization component (magnetization in the direction parallel to the sample surface) of the sample can be measured by detecting the rotation of the polarization plane due to the longitudinal Kerr effect generated in the reflected light when the probe light is incident obliquely. (Figure 1 left). On the other hand, the perpendicular magnetization component (magnetization in the direction perpendicular to the sample surface) of the sample is measured by detecting the rotation of the polarization plane due to the polar Kerr effect generated in the reflected light when the probe light is incident in the perpendicular direction. (Right figure in FIG. 1).

  However, when the incident light is incident obliquely, the polarization plane of the reflected light is not only rotated by the polarization in the in-plane direction, but actually the vertical magnetization is polarized through the polar Kerr effect. Is included (the central view in FIG. 1). Therefore, the measurement result of the in-plane magnetization obtained by obliquely entering the incident light includes an error due to the perpendicular magnetization.

  For example, Non-Patent Document 1 discloses a technique for avoiding the problem of mixing of perpendicular magnetization components when incident light is incident obliquely. In this non-patent document 1, sampling is performed in which incident light is incident on a sample in the vertical direction and a in-plane magnetization component and a perpendicular magnetization component are separated using a split half-wave plate in which polarizing plates having different optical axis orientations are joined. A Kerr-effect scanning laser microscope is disclosed.

  However, the Kerr effect scanning laser microscope can only measure the in-plane magnetization component and the perpendicular magnetization component at one location of the sample, and cannot obtain an image representing the magnetization state. Specifically, in this technique, the reflected light beam is separated by a polarizing beam splitter, and the light intensity is differentially detected by two detectors, so the in-plane magnetization component and the perpendicular magnetization component at each position of the sample are measured. To do this, the sample must be scanned. In fact, the Kerr effect scanning laser microscope disclosed in Non-Patent Document 1 is provided with a piezoelectric stage for scanning a sample.

  It is desirable to provide a technique that can obtain an image representing the state of magnetization (without scanning the sample) while separating the in-plane magnetization component and the perpendicular magnetization component. It is also desirable to provide a technique that can obtain an image representing a magnetic physical quantity with respect to a magnetic physical quantity (for example, a magnetic field) that contributes to rotation of a polarization plane other than magnetization.

JP 2008-224907 A

Toshiaki Nagai et al., “Measurement of perpendicular and in-plane magnetization components using a broadband Kerr microscope”, 26th Annual Meeting of the Japan Society of Response Magnetics (2002), p. 398

  Therefore, an object of the present invention is to obtain an image representing a magnetic physical quantity while separating an in-plane component and a vertical component with respect to a magnetic physical quantity (for example, magnetization and magnetic field) that contributes to the rotation of the polarization plane. To provide technology.

  Specifically, according to one aspect of the present invention, the magnetic property measuring apparatus includes a light incident mechanism for causing linearly polarized incident light to enter the sample, and reflected light obtained by reflecting the incident light to the sample. , An image pickup device for picking up an image by picking up signal light obtained by passing the reflected light through the analyzer, and a calculation device. The light incident mechanism is configured such that an incident direction in which the incident light is incident on the sample is variable. When the light incident mechanism enters the linearly polarized first incident light into the sample in a first incident direction that is in the plane of the first incident surface and the incident angle is not 0 °, the imaging apparatus The first reflected light obtained by reflecting the first incident light by means of the first signal light obtained by passing through the analyzer, the first corresponding to the rotation angle of the polarization plane at each position of the sample. Get an image. The sample is in a second incident direction such that the light incident mechanism has linearly polarized second incident light in the plane of the first incident surface and the incident angle is the same as the reflection angle of the first reflected light. The imaging device is configured to detect the second reflected light obtained by reflecting the second incident light by the sample and passing through the analyzer based on the second signal light. A second image corresponding to the rotation angle of the polarization plane at each position is acquired. The arithmetic device is an image of a component in a first direction, which is an in-plane direction of the sample, of a magnetic physical quantity contributing to rotation of a polarization plane by calculating the first image and the second image. A one-component image and a second component image that is an image of a component of the magnetic physical quantity in a second direction that is a vertical direction of the sample are generated.

  In the magnetic property measuring apparatus, the light incident mechanism may cause the linearly polarized third incident light to be in the plane of the second incident surface perpendicular to the first incident surface and the incident angle is not 0 °. Third signal light obtained when the imaging device receives third reflected light obtained by reflecting the third incident light by the sample when passing through the analyzer when the sample enters the sample in three incident directions. A third image corresponding to the rotation angle of the polarization plane at each position of the sample is acquired, and the light incident mechanism has a linearly polarized fourth incident light in the plane of the second incident plane; In addition, when the incident light enters the sample in the fourth incident direction so that the incident angle is the same as the reflection angle of the third reflected light, the imaging device obtains the fourth incident light by the sample. The fourth signal obtained by passing the fourth reflected light passing through the analyzer On the basis of the light, it may acquire a fourth image corresponding to the rotation angle of the polarization plane at respective positions of the sample. In this case, the computing device computes the third image and the fourth image, whereby the magnetic physical quantity is in the in-plane direction of the sample and is in a third direction perpendicular to the first direction. A third component image that is an image of the component at is generated. The computing device may generate a fourth component image that is an image of the component of the magnetic physical quantity in the second direction by computing the third image and the fourth image.

  In one embodiment, the magnetic physical quantity is a magnetization at each position of the sample. When a medium exhibiting the Faraday effect is used as a sample, the magnetic physical quantity can be a magnetic field at each position of the medium.

In another aspect of the present invention, a magnetic property measurement method includes:
Linearly polarized first incident light is incident on the sample in a first incident direction such that the first incident light is in the plane of the first incident surface and the incident angle is not 0 °;
Acquiring a first image corresponding to a rotation angle of a polarization plane at each position of the sample based on first reflected light obtained by reflecting the first incident light by the sample;
Entering linearly polarized second incident light into the sample in a second incident direction that is in the plane of the first incident surface and has the same incident angle as the reflection angle of the first reflected light When,
Obtaining a second image corresponding to the rotation angle of the polarization plane at each position of the sample, based on the second reflected light obtained by reflecting the second incident light by the sample;
A first component image that is an image of a component in a first direction that is an in-plane direction of the sample of a magnetic physical quantity that contributes to rotation of a polarization plane by calculating the first image and the second image; Obtaining a second component image that is an image of a component of the magnetic physical quantity in a second direction that is a vertical direction of the sample.

The magnetic property measurement method is
Furthermore,
Linearly polarized third incident light is incident on the sample in a third incident direction that is in the plane of the second incident surface perpendicular to the first incident surface and the incident angle is not 0 °;
Acquiring a third image corresponding to the rotation angle of the polarization plane at each position of the sample, based on the third reflected light obtained by reflecting the third incident light by the sample;
Entering linearly polarized fourth incident light into the sample in a fourth incident direction that is in the plane of the second incident surface and has the same incident angle as the reflection angle of the third reflected light When,
Obtaining a fourth image corresponding to a rotation angle of a polarization plane at each position of the sample, based on fourth reflected light obtained by reflecting the fourth incident light by the sample;
By calculating the third image and the fourth image, a third magnetization that is an image of a component of the magnetic physical quantity in the third direction that is in the in-plane direction of the sample and is perpendicular to the first direction. Obtaining an image.

  In one embodiment of the magnetic property measurement method, the magnetic physical quantity is a magnetization at each position of the sample. When a medium exhibiting the Faraday effect is used as a sample, the magnetic physical quantity can be a magnetic field at each position of the medium.

In still another aspect of the present invention, a magnetic property measurement method includes:
Placing a Faraday medium exhibiting a Faraday effect at a location where a magnetic field is measured;
Linearly polarized first incident light is incident on the Faraday medium in a first incident direction that is in the plane of the first incident surface and whose incident angle is not 0 °;
Acquiring a first image corresponding to a rotation angle of a polarization plane at each position of the Faraday medium based on first reflected light obtained by reflecting the first incident light by the Faraday medium;
The linearly polarized second incident light is incident on the Faraday medium in a second incident direction that is in the plane of the first incident surface and has the same incident angle as the reflection angle of the first reflected light. Steps,
Acquiring a second image corresponding to a rotation angle of a polarization plane at each position of the Faraday medium based on second reflected light obtained by reflecting the second incident light by the Faraday medium;
By calculating the first image and the second image, a first magnetic field component image that is an image of a magnetic field component in a first direction that is an in-plane direction of the Faraday medium, and a first magnetic field component image that is perpendicular to the Faraday medium. Obtaining a second magnetic field component image that is an image of magnetic field components in two directions.

The magnetic field measurement method is
Furthermore,
Linearly polarized third incident light is incident on the Faraday medium in a third incident direction that is in a plane of a second incident surface perpendicular to the first incident surface and whose incident angle is not 0 °; ,
Acquiring a third image corresponding to a rotation angle of a polarization plane at each position of the Faraday medium based on third reflected light obtained by reflecting the third incident light by the Faraday medium;
The linearly polarized fourth incident light is incident on the Faraday medium in a fourth incident direction that is in the plane of the second incident surface and has the same incident angle as that of the third reflected light. Steps,
Obtaining a fourth image corresponding to a rotation angle of a polarization plane at each position of the Faraday medium based on fourth reflected light obtained by reflecting the fourth incident light by the Faraday medium;
By calculating the third image and the fourth image, a third magnetic field component image that is an image of a magnetic field component in a third direction that is in-plane direction of the Faraday medium and perpendicular to the first direction is obtained. Obtaining a step.

  According to the present invention, it is possible to obtain an image representing a magnetic physical quantity while separating an in-plane component and a vertical component with respect to a magnetic physical quantity (for example, magnetization and magnetic field) contributing to the rotation of the polarization plane.

It is a figure explaining the vertical Kerr effect and polar Kerr effect which occur when incident light injects in the diagonal direction. It is a figure explaining the principle of the magnetic characteristic measuring method of this invention. It is a figure which shows the observation procedure of the magnetic domain of the in-plane magnetization sample in one Embodiment of this invention. It is a figure which shows the observation procedure of the magnetic domain of a perpendicular magnetization sample in one Embodiment of this invention. It is a figure which shows the observation result of the NiFe soft-magnetic pattern film obtained with the magnetic characteristic measuring method of this embodiment. It is a figure which shows the observation result of the GdFeCo pattern film obtained with the magnetic characteristic measuring method of this embodiment. It is a figure explaining the method which injects incident light from four directions and detects a three-dimensional magnetization component in one Embodiment of this invention. It is a figure which shows the X direction component image of the grain-oriented electrical steel plate obtained with the magnetic characteristic measuring method of this embodiment. It is a figure which shows the Y direction component image of the grain-oriented electrical steel plate obtained with the magnetic characteristic measuring method of this embodiment. It is a figure which shows the Z direction component image of the grain-oriented electrical steel plate obtained with the magnetic characteristic measuring method of this embodiment. It is a figure which shows the structure of the magnetic characteristic measuring apparatus of one Embodiment of this invention. It is a figure which shows switching of the incident direction of the incident light in the magnetic characteristic measuring apparatus of FIG. It is a figure which shows the rotation of the polarization plane by the vertical Kerr effect and polar Kerr effect when incident light injects in the diagonal direction. FIG. 6 is a diagram illustrating a relationship among a magnetization component Mx in the X-axis direction, a magnetization component My in the Y-axis direction, a magnetization component Mz in the Z-axis direction, and the total magnetization M. It is a flowchart which shows the procedure which calculates the magnetization direction of each position of an X direction component image, a Y direction component image, a Z direction component image, and a sample in one Embodiment of this invention. It is a flowchart which shows the procedure which acquires reference | standard data in calculation of the magnetization direction of each position of the sample in one Embodiment of this invention. It is a flowchart which shows the procedure which obtains observation image data in calculation of the magnetization direction of each position of the sample in one Embodiment of this invention. It is a figure which shows the arithmetic processing which obtains an X direction component image in calculation of the magnetization direction of each position of the sample in one Embodiment of this invention. It is a figure which shows the arithmetic processing which obtains a Y direction component image in calculation of the magnetization direction of each position of the sample in one Embodiment of this invention. It is a figure which shows the arithmetic processing which obtains a Z direction component image from the image obtained by observation of a X-axis direction in calculation of the magnetization direction of each position of the sample in one Embodiment of this invention. It is a figure which shows the arithmetic processing which obtains a Z direction component image from the image obtained by observation of the Y-axis direction in calculation of the magnetization direction of each position of the sample in one Embodiment of this invention. It is a figure explaining the calculation method of X normalization data in the calculation of the magnetization direction of one Embodiment of this invention, and Y normalization data. It is a figure explaining the magnetic field detection by the magnetic transfer in one Embodiment of this invention. It is a figure which shows the structure of the Faraday medium and arrangement | positioning of a magnetic field generation source in one Embodiment. It is a flowchart which shows the procedure which calculates the component of each direction of the magnetic field in one Embodiment of this invention. It is a flowchart which shows the procedure which acquires reference | standard data in calculation of the component of each direction of the magnetic field in one Embodiment of this invention. It is a flowchart which shows the procedure of obtaining observation image data in calculation of the component of each direction of the magnetic field in one Embodiment of this invention. It is a figure which shows the arithmetic processing which obtains an X direction component image in calculation of the component of each direction of the magnetic field in one Embodiment of this invention. It is a figure which shows the arithmetic processing which obtains a Y direction component image in calculation of the component of each direction of the magnetic field in one Embodiment of this invention. It is a figure which shows the arithmetic processing which obtains a Z direction component image from the image obtained by observation of an X-axis direction in calculation of the component of each direction of the magnetic field in one Embodiment of this invention. It is a figure which shows the arithmetic processing which obtains a Z direction component image from the image obtained by observation of a Y-axis direction in calculation of the component of each direction of the magnetic field in one Embodiment of this invention. It is a figure explaining the calculation method of X standardization data and Y standardization data in calculation of the magnetic field direction of one embodiment of the present invention.

(Principle of magnetic property measurement method)
Below, the principle of the magnetic property measuring method of one embodiment of the present invention will be described.
FIG. 2 is a diagram for explaining the principle of the magnetic characteristic measuring method of the present embodiment. The basic principle of the magnetic property measuring apparatus of this embodiment is that an image representing an in-plane magnetization component and an image representing a perpendicular magnetization component are obtained by calculating images obtained by making incident light incident in different directions. Is. In FIG. 2, an XYZ orthogonal coordinate system is defined. The X axis and Y axis are defined in the in-plane direction (direction parallel to the surface) of the sample, and the Z axis is defined in the vertical direction (direction perpendicular to the surface) of the sample.

First, when linearly polarized incident light _IIN1 is incident on a sample in the direction of a specific incident angle θ _i1 , the sample reflects the incident light _IIN1 to obtain reflected light _IR1 . In FIG. 2, the incident light I _IN1 has an incident surface (an incident surface in which both the traveling direction of the incident light I _{IN1 and} the traveling direction of the reflected light I _R1 exist in the plane) parallel to the X-axis direction ( In other words, the light is incident so that the component in the X-axis direction of the traveling direction of the incident light _IIN1 is positive. Here, the incident light I _IN1 is incident on the sample in an oblique direction. In other words, the incident angle θ _i1 is not 0 ° (in this specification, the direction perpendicular to the surface of the sample S is defined as the incident angle is 0 °). When the reflected light _IR1 enters and passes through an analyzer (not shown in FIG. 2), signal light having a light intensity distribution corresponding to the rotation angle of the polarization plane at each position of the sample is obtained. The signal light is converted into an image sensor (for example, a CCD (charge charring device) image sensor or a CMOS (complementary
A first image is obtained by imaging with a metal oxide semiconductor) imaging element). Hereinafter, obtaining an image by entering incident light in a direction in which the component in the X-axis direction is positive in an incident plane parallel to the XZ plane may be referred to as “observation in the positive direction of the X-axis”.

Further, the incident direction is reversed and incident light I _IN2 is incident (that is, within the plane of the incident surface of incident light I _IN1 and having the same incident angle θ _i2 as the reflection angle of reflected light I _R1 ). The second image is obtained by imaging the signal light obtained by making the incident light I _IN2 incident in the direction and passing the reflected light _IR2 through the analyzer. Here, in FIG. 2, the incident light I _IN2 has an incident surface parallel to the X-axis direction (that is, parallel to the XZ plane) and a component in the X-axis direction of the traveling direction of the incident light I _IN2. Incident so as to be negative. Hereinafter, obtaining an image by entering incident light in a direction in which the component in the x-axis direction is negative in an incident plane parallel to the XZ plane may be referred to as “observation in the negative direction of the X-axis”.

  Here, in the magnetic characteristic measuring method of this embodiment, when the incident direction is reversed, the direction of rotation of the polarization plane due to the longitudinal Kerr effect induced by the in-plane magnetization component (the direction of the rotation angle θx in FIG. 2). 2 is reversed, whereas the polarization plane rotation direction (direction of the rotation angle θz in FIG. 2) due to the polar Kerr effect induced by the perpendicular magnetization component is not reversed. The difference image between the first image and the second image is an image representing an in-plane magnetization component (strictly, an in-plane magnetization component parallel to the X-axis direction) at each position of the sample. On the other hand, an image obtained by adding the first image and the second image is an image representing a perpendicular magnetization component at each position of the sample. As described above, by adding or subtracting the first image and the second image, an image in which the in-plane magnetization component and the perpendicular magnetization component are separated can be obtained.

  By using such a method, it is possible to observe the magnetic domain of the in-plane magnetization component and the magnetic domain of the perpendicular magnetization component while separating the influence of the in-plane magnetization component and the perpendicular magnetization component. 3A and 3B are conceptual diagrams showing a procedure for observing magnetic domains in the magnetic property measuring apparatus according to the present embodiment. FIG. 3A is a conceptual diagram of a case where a magnetic domain of a sample having in-plane magnetization (in-plane magnetic anisotropy) is observed, and FIG. 3B is a diagram of a sample having perpendicular magnetization (perpendicular magnetic anisotropy). It is a conceptual diagram about the case where observation of a magnetic domain is performed. In the following, the case where the sample has two magnetic domains having magnetizations in opposite directions will be discussed.

  In the observation of the magnetic domain, it is preferable to exclude information other than the magnetic domain information. Therefore, in this embodiment, as shown in FIGS. 3A and 3B, an image (observation image) of a sample to be observed and a saturation magnetic field (a magnetic field large enough to saturate the magnetization of the sample) are provided. The difference image obtained as the difference between the images of the standard sample in the applied state (saturated image) is acquired while inverting the incident direction, and by calculating the difference image, the image of the magnetic domain of the in-plane magnetization component, and the surface An image of the magnetic domain of the inner magnetization component is obtained. Note that the standard sample may not be a sample prepared separately from the sample to be observed. That is, the saturation image may be an image obtained in a state where a saturation magnetic field is applied to the sample to be observed itself.

Specifically, when “observed in the positive direction of the X axis” (when incident light I _IN1 is incident on the sample in the direction of a specific incident angle θ _i1 ), and when “observed in the negative direction of the X axis” The object to be observed in both cases (when the incident light I _IN2 is incident in the direction of the incident angle θ _i2 that is in the plane of the incident surface of the incident light I _IN1 and is the same as the reflection angle of the reflected light I _R1 ) An observation image which is an image of the sample is obtained. Furthermore, for both the “observation in the positive direction of the X axis” and the “observation in the negative direction of the X axis”, the saturation magnetic field (of sufficient magnitude to direct the magnetization of the entire sample in the same direction). A saturation image which is an image of a standard sample in a state where a magnetic field is applied is obtained. The saturation magnetic field is preferably applied in the in-plane direction of the sample if it is a sample having in-plane magnetization as a whole, and is preferably applied in the vertical direction of the sample if it is a sample having vertical magnetization as a whole.

Further, a difference image between the observed image and the saturated image when “observed in the positive direction of the X axis” is calculated. Hereinafter, this difference image is referred to as an “incident from the left” image (since it is shown in FIG. 2 that the incident light I _IN1 is incident from the left). Further, the incident direction is reversed, and a difference image between the observed image and the saturated image when “observed in the negative direction of the X axis” is calculated. Hereinafter, this difference image is referred to as an “incident from the right” image. Here, it should be noted that “left” and “right” have only a meaning for distinguishing directions.

  The difference image between the “incident from the left” image and the “incident from the right” image is an image of the in-plane magnetization component. As shown in FIG. 3A, for a sample having in-plane magnetization, two magnetic domains are observed as two regions having different luminances in the in-plane magnetization component image, as shown in FIG. 3B. In addition, for the sample having perpendicular magnetic anisotropy, no magnetic domain is observed in the image of the in-plane magnetization component.

  On the other hand, the difference image between the “incident from the left” image and the “incident from the right” image is an image of the perpendicular magnetization component. For example, as shown in FIG. 3A, for a sample having in-plane magnetization, a magnetic domain is observed in the image of the perpendicular magnetization component, and as shown in FIG. 3B, a sample having perpendicular magnetic anisotropy. In the image of the perpendicular magnetization component, two magnetic domains are observed as two regions having different luminances.

  4A and 4B show an “incident from left” image, an “incident from right” image, an in-plane magnetization component image, and a perpendicular magnetization component image of an actual sample. Here, FIG. 4A is an image of a NiFe soft magnetic pattern film (which is a film having in-plane magnetization), and FIG. 4B is an image of a GdFeCo pattern film (which is a film having perpendicular magnetization). As understood from FIGS. 4A and 4B, according to the method of this embodiment, in the NiFe soft magnetic pattern film, each magnetic domain exhibits in-plane magnetization from the in-plane magnetization component image and the perpendicular magnetization component image. You can see that On the other hand, for the GdFeCo pattern film, it can be seen from the image of the in-plane magnetization component and the image of the perpendicular magnetization component that each magnetic domain has substantially perpendicular magnetization.

  In the method in which incident light is incident from two directions as shown in FIG. 2, an in-plane magnetization component parallel to the incident surface and a perpendicular magnetization component can be observed. Extending this method, as shown in FIG. 5, observing a three-dimensional magnetization component by entering incident light from two directions (from a total of four directions) on each of incident surfaces perpendicular to each other. Can do.

  Specifically, an observation image and a saturation image are taken by “observing in the positive direction of the X axis”, and a difference image between these observation images and the saturation image is calculated as an “incident from the left” image. Further, by inverting the incident direction and “observing in the negative direction of the X axis”, an observation image and a saturation image are taken, and a difference image between the observation image and the saturation image is calculated as an “incident from the right” image.

  The difference image between the “incident from left” image and the “incident from right” image is the image of the magnetization component in the X-axis direction, and the added image of the “incident from left” image and the “incident from right” image is Z It is an image of the magnetization component (perpendicular magnetization component) of an axial direction.

Further, on the incident plane parallel to the YZ plane, the linearly polarized incident light I _IN3 is incident on the sample in the direction of a specific incident angle θ _i2 , and an observation image and a saturation image are photographed. Here, in FIG. 5, the incident light I _IN3 has an incident surface parallel to the Y-axis direction (that is, parallel to the YZ plane) and a component in the Y-axis direction of the traveling direction of the incident light I _IN3. Incident to be positive. Hereinafter, obtaining an image by entering incident light in a direction in which the component in the Y-axis direction is positive in an incident plane parallel to the YZ plane may be referred to as “observation in the positive direction of the Y-axis”. Further, the difference image between the observed image and the saturated image obtained by “observing in the positive direction of the Y axis” is calculated as an “incident from the front” image.

Further, the incident direction is reversed in the plane of the incident surface, and linearly polarized incident light _IIN4 is incident on the sample, and an observation image and a saturated image are photographed. Here, in FIG. 5, the incident light I _IN4 has an incident surface parallel to the Y-axis direction (that is, parallel to the YZ plane) and a component in the Y-axis direction of the traveling direction of the incident light I _IN4. Incident so as to be negative. Hereinafter, obtaining an image by entering incident light in a direction in which a component in the Y-axis direction is negative in an incident plane parallel to the YZ plane may be referred to as “observation in the negative Y-axis direction”. Further, a difference image between the observed image and the saturated image obtained by “observing in the negative direction of the Y axis” is calculated as an “incident from behind” image. Here, it should be noted that “front” and “back” have only a meaning for distinguishing directions.

  The difference image between the “incident from the front” image and the “incident from the rear” image is the image of the magnetization component in the Y-axis direction, and the added image of the “incident from the front” image and the “incident from the rear” image is Z It is an image of the magnetization component of an axial direction.

  In this method, there are two images of the magnetization component in the Z-axis direction (an image of the magnetization component in the Z-axis direction obtained by entering incident light on the incident surface parallel to the XZ plane and an incident surface parallel to the YZ plane). An image of a magnetization component in the Z-axis direction obtained by entering incident light) is obtained. An average image of these images may be an image of the magnetization component in the Z-axis direction finally obtained.

  6A to 6C are examples of images of magnetization components in each direction obtained by entering incident light from four directions. A grain-oriented electrical steel sheet is used as the sample. Here, FIG. 6A shows an X axis obtained as a difference image between an “incident from the left” image and an “incident from the right” image obtained by entering incident light from two directions on an incident surface parallel to the XZ plane. It is an image of the magnetization component of a direction. FIG. 6B shows the magnetization in the Y-axis direction obtained as a difference image between an “incident from the front” image and an “incident from the rear” image obtained by entering incident light from two directions on the incident plane parallel to the YZ plane. It is an image of a component. FIG. 6C shows the magnetization in the Z-axis direction obtained as an addition image of an “incident from left” image and an “incident from right” image obtained by entering incident light from two directions on an incident surface parallel to the XZ plane. It is an image of a component.

(Overall configuration of magnetic property measuring device)
FIG. 7 is a perspective view showing an example of the configuration of a magnetic property measuring apparatus for carrying out the magnetic property measuring method described above. 7 schematically includes an incident optical system 1, an incident optical system 2, a detection optical system 3, an arithmetic device 4, a display device 5, and a quadrupole electromagnet device 6. ing.

  The incident optical system 1 has a function of generating linearly polarized incident light 7 incident on the sample S. Specifically, the incident optical system 1 includes a light source 11, a condenser lens 12, an aperture stop 13, a field stop 14, a collimator lens 15, a mirror 16, a movable mirror 17, a relay lens 18, and a polarization. And a child 19. The light generated by the light source 11 is incident on the mirror 16 via the condenser lens 12, the aperture stop 13, the field stop 14, and the collimator lens 15, and further reflected by the mirror 16 and incident on the movable mirror 17. . The movable mirror 17 is configured to be rotatable about the x axis and the z axis. As will be described later, the movable mirror 17 plays an important role in order to allow the incident light 7 to be incident on the sample S in a desired incident direction. The light reflected by the movable mirror 17 enters the polarizer 19 via the relay lens 18, and the light emitted from the polarizer 19 is used as the incident light 7.

  The epi-illumination optical system 2 has a function of causing the incident light 7 to enter the sample S in a desired direction, and further causing the reflected light 8 from the sample S to enter the detection optical system 3. More specifically, the incident optical system 2 includes a Smith mirror 21, a half mirror 22, and an objective lens 23. Incident light 7 incident from the incident optical system 1 is reflected by the Smith mirror 21 and the half mirror 22 and enters the objective lens 23. The objective lens 23 enters the incident light 7 into the sample S, and the reflected light 8 from the sample S enters the detection optical system 3 via the half mirror 22. The positions of the movable mirror 17 and the relay lens 18 described above may be any of the optical path length from the front focal point of the objective lens 23 to the principal point of the relay lens 18 and the optical path length from the principal point of the relay lens 18 to the movable mirror 17. Is also set to coincide with the focal length of the relay lens 18.

  The detection optical system 3 includes an analyzer 31, an imaging lens 32, and an imaging device 33. The reflected light 8 is incident on the imaging device 33 via the analyzer 31 and the imaging lens 32. The imaging device 33 captures a captured image of the incident reflected light 8 with an imaging device (for example, a CCD imaging device or a CMOS imaging device) and sends the captured image to the arithmetic device 4. The luminance of each pixel of the captured image indicates the light intensity at each position of the spot of the reflected light 8.

  The quadrupole electromagnet device 6 is a device that applies a magnetic field to the sample S in a desired direction, and includes quadrupole electromagnets 61 to 64 and bipolar power supplies 65 and 66. The quadrupole electromagnets 61 and 62 have a function of applying a magnetic field to the sample S in the X-axis direction, and are driven by a bipolar power source 65. The quadrupole electromagnets 63 and 64 have a function of applying a magnetic field to the sample S in the Y-axis direction, and are driven by a bipolar power supply 66. The intensity and direction of the magnetic field applied to the sample S are the magnitude of the current that the bipolar power supply 65 supplies to the quadrupole electromagnets 61 and 62 and the magnitude of the current that the bipolar power supply 66 supplies to the quadrupole electromagnets 63 and 64. Controlled by.

The arithmetic device 4 performs arithmetic processing and control processing in the magnetic characteristic measuring device.
First, the arithmetic unit 4 controls the direction of the incident light 7 to the sample S by controlling the direction of the movable mirror 17 of the incident optical system 1. Incident light from the two directions shown in FIG. 2 and incident light from the four directions shown in FIG. 4 are realized by controlling the direction of the movable mirror 17. FIG. 8 is a diagram illustrating the relationship between the control of the direction of the movable mirror 17 and the incident direction of the incident light 7. By rotating the movable mirror 17 around a central axis parallel to the Z axis and directing it in a desired direction, the incident light 7 generated by the light source 11 is as shown in FIG. The light is incident parallel to the optical axis at a position on the body-mounted surface of the objective lens 23 that is shifted in the X-axis direction from the optical axis of the objective lens 23. Thereby, the incident light 7 can be incident on the sample S obliquely with the incident surface parallel to the XZ plane. On the other hand, by rotating the movable mirror 17 around a central axis parallel to the X axis and directing the movable mirror 17 in a desired direction, incident light 7 generated by the light source 11 is reflected by the objective lens on the body surface of the objective lens 23. The light is incident parallel to the optical axis at a position shifted from the optical axis 23 in the Y-axis direction. Thereby, the incident light 7 can be incident on the sample S obliquely with the incident surface parallel to the YZ plane.

  Secondly, the arithmetic device 4 controls the current supplied from the bipolar power supplies 65 and 66 of the quadrupole electromagnet device 6 to the quadrupole electromagnets 61, 62, 63 and 64, and the intensity of the magnetic field applied to the sample S. And control the orientation. In the configuration of the quadrupole electromagnet device 6 in FIG. 7, the magnetic field can be applied in an arbitrary in-plane direction of the sample S (a direction in a plane parallel to the XY plane).

  Third, the arithmetic device 4 performs arithmetic processing of the above-described magnetic characteristic measurement method on the captured image of the reflected light 8 imaged by the imaging device 33, and obtains an in-plane magnetization component image and a perpendicular magnetization component image. Or images of magnetization components in the X-axis direction, the Y-axis direction, and the Z-axis direction are generated. Further, if necessary, the arithmetic device 4 performs the arithmetic processing described later, the magnetization direction and / or the magnetization component in each direction (X-axis direction, Y-axis direction, Z-axis direction) at each position of the sample from the captured image. The size of is calculated.

  In addition, the arithmetic device 4 displays a display image to be displayed on the display device 5 (for example, an in-plane magnetization component image and a perpendicular magnetization component image, or magnetization components in the X-axis direction, the Y-axis direction, and the Z-axis direction). Image). The display device 5 displays the display image sent from the arithmetic device 4.

(Calculation of magnetization direction)
The luminance data of each pixel of the image of the magnetization component in the X-axis direction obtained by the magnetic characteristic measurement method described above corresponds to the magnitude of magnetization in the X-axis direction at the corresponding position of the sample. Similarly, the luminance data of each pixel of the image of the magnetization component in the Y-axis direction corresponds to the magnitude of magnetization in the Y-axis direction at the corresponding position of the sample, and the magnetization component in the Z-axis direction (vertical magnetization component) The luminance data of each pixel in the image corresponds to the magnitude of magnetization in the Z-axis direction at the corresponding position of the sample. Accordingly, the luminance data of each pixel of the image of the magnetization component in the X-axis direction, the Y-axis direction, and the Z-axis direction includes information on the three-dimensional magnetization direction and the magnetization magnitude at each position of the sample S. . Therefore, in principle, from the luminance data of each pixel of the magnetization component image in the X-axis direction, the Y-axis direction, and the Z-axis direction (or the data from which the luminance data is calculated), The magnitude of the magnetization direction in the three-dimensional space at the position can be calculated.

Specifically, as understood from FIG. 9A, the rotation angle θx of the polarization plane due to the longitudinal Kerr effect of the magnetization component Mx in the X-axis direction, and the rotation angle θy of the polarization plane due to the longitudinal Kerr effect of the magnetization component My in the Y-axis direction. , And the rotation angle θz of the polarization plane due to the polar Kerr effect of the perpendicular magnetization component (magnetization component in the Z-axis direction) is expressed as follows:
θx = K _L · Mx · sin θ _i , (1a)
θy = K _L · My · sin θ _i , (1b)
θz = K _P · Mz · cos θ _i , (1c)
Here, K _L is a proportionality constant that depends on the Kerr constant of the longitudinal Kerr effect, K _P is a proportionality constant that depends on the Kerr constant of the polar Kerr effect, the theta _i is the incident angle.

Thus, the following equation holds:
_{Mx = θx / (K L ·} sinθ i), ··· (2a)
My = θy / (K _L · sin θ _i ), (2b)
Mz = θz / (K _P · cos θ _i ), (2c)
Polarization plane rotation angle [theta] x, [theta] y, since θz can be obtained from the luminance data of the image, in principle, the Kerr constant of the material of the sample S, and, knowing the angle of incidence theta _i is represented by the formula (2a) ~ From (2c), the magnetization component Mx in the X-axis direction, the magnetization component My in the Y-axis direction, and the magnetization component Mz in the Z-axis direction at each position of the sample S can be calculated.

One problem is that it may be difficult to measure an accurate value of the incident angle θ _i . Particularly, in the case of using incoherent white illumination as the light source 11 in order to take a large captured image, different incident angle theta _i depending on the position of the sample S, to accurately measure the incident angle theta _i at each position It is difficult. When an accurate value of the incident angle θ _i cannot be obtained, the magnetization component Mx in the X-axis direction, the magnetization component My in the Y-axis direction, and the magnetization component Mz in the Z-axis direction are calculated from the equations (2a) to (2c). It is not possible.

However, as will be discussed below, the magnetization direction at each position of the sample S can be calculated without using the incident angle θ _i . Hereinafter, a method for calculating the magnetization direction at each position of the sample S without using the incident angle θ _i will be discussed.

  As shown in FIG. 9B, in the ferromagnetic sample S, it can be considered that the total magnetization M is directed in a specific direction at each position of the sample. The ratio Mx / M of the magnetization component in the X-axis direction and the total magnetization M at a specific position of the sample S is the luminance data of the observation image of the magnetization component in the X-axis direction of the ferromagnetic sample S and the X-axis direction. It can be calculated from the luminance data of the saturated image when the sample S is saturated. Similarly, the ratio My / M of the magnetization component in the Y-axis direction and the total magnetization M at a specific position of the sample S is the luminance data of the observation image of the magnetization component in the Y-axis direction of the ferromagnetic sample S and the Y-axis direction. The ratio My / M of the magnetization component in the Z-axis direction and the total magnetization M at a specific position of the sample S can be calculated from the luminance data of the saturated image when the sample S is saturated to the sample S. Can be calculated from the luminance data of the observed image of the magnetization component in the Z-axis direction and the luminance data of the saturated image when the sample S is saturated in the Z-axis direction. Since Mx / M, My / M, and Mz / M are direction cosines of the direction vector of the magnetization direction of the sample S, if Mx / M, My / M, and Mz / M can be calculated from the observation image and the saturation image, This means that the magnetization direction at each position of the sample S can be calculated.

  One problem with such a technique is that it may be difficult to saturate the magnetization of the sample S in all of the X-axis direction, the Y-axis direction, and the Z-axis direction. First, a thin plate material has a large demagnetizing field, making it difficult to saturate magnetization in the Z-axis direction. In addition, an electromagnet device capable of generating a large magnetic field in each of the X-axis direction, the Y-axis direction, and the Z-axis direction is actually difficult to manufacture. For example, the quadrupole electromagnet device 6 shown in FIG. 7 can generate a large magnetic field in the direction in the XY plane, but cannot generate a magnetic field in the Z-axis direction. This means that it is difficult to obtain the ratio Mz / M by measurement.

Therefore, in the present embodiment, the following expression (4) is established for the magnetization component Mx in the X-axis direction, the magnetization component My in the Y-axis direction, and the magnetization component Mz in the Z-axis direction:
Paying attention to this, an approach is used in which Mx / M and My / M are obtained from the measurement results, while Mz / M is calculated from Equation (4).

FIG. 10 shows an image of the magnetization component in the X-axis direction, an image of the magnetization component in the Y-axis direction, an image of the magnetization component in the Z-axis direction, and a sample (in a situation where the incident angle θ _i is unknown) in this embodiment. It is a flowchart which shows the procedure which obtains the magnetization direction in each position of S.

Step S01:
First, reference data, that is, an image (saturation magnetic field application image) when a magnetic field (saturation magnetic field) that saturates the sample S is applied is acquired. FIG. 11 is a flowchart showing details of acquisition of the saturation magnetic field application image in step S01.

First, saturation magnetic field application images XF _PS and XF _MS are acquired by observing in the positive direction of the X axis (step S11). Here, as described above, “observation in the positive direction of the X axis” means that incident light is incident in an incident direction that is in a plane parallel to the XZ plane and includes a component in the positive direction of the X axis (see FIG. 2 means that incident light I _IN1 ) is incident to obtain a captured image. Here, the saturation magnetic field application image XF _PS is a captured image acquired in a state in which a magnetic field that saturates the sample S is applied in the positive direction of the X axis by the quadrupole electromagnet apparatus 6, and the saturation magnetic field application image XF _MS is It is the captured image acquired in the state which applied the magnetic field which saturates the sample S by the quadrupole electromagnet apparatus 6 to the negative direction of the X-axis.

Further, saturation magnetic field application images XR _PS and XR _MS are acquired by observing in the negative direction of the X axis (step S12). Here, as described above, “observation in the negative direction of the X axis” means that incident light is incident in an incident direction that is in a plane parallel to the XZ plane and includes a component in the negative direction of the X axis (see FIG. 2 means that incident light I _IN2 ) is incident to obtain a captured image. Here, the saturation magnetic field application image XR _PS is a captured image acquired in a state in which a magnetic field that saturates the sample S is applied in the positive direction of the X axis by the quadrupole electromagnet apparatus 6, and the saturation magnetic field application image XR _MS is It is the captured image acquired in the state which applied the magnetic field which saturates the sample S to the negative direction of the X-axis.

Further, saturation magnetic field application images YF _PS and YF _MS are obtained by observing in the positive direction of the Y axis (step S13). Here, “observation in the positive direction of the Y-axis” means that a captured image is obtained by entering incident light in an incident direction that is in a plane parallel to the YZ plane and includes a component in the positive direction of the Y-axis. Means. Further, the saturation magnetic field application image YF _PS is a captured image obtained in a state where a magnetic field for saturating the sample S is applied in the positive direction of the Y axis by the quadrupole electromagnet device 6, and the saturation magnetic field application image YF _MS is It is the captured image acquired in the state which applied the magnetic field which saturates S to the negative direction of the Y-axis.

Further, saturation magnetic field application images YR _PS and YR _MS are acquired by observing in the negative direction of the Y axis (step S14). Here, “observation in the negative direction of the Y axis” refers to obtaining a captured image by entering incident light in an incident direction that is in a plane parallel to the YZ plane and includes a component in the negative direction of the Y axis. Means. Further, the saturation magnetic field application image YR _PS is a captured image acquired in a state where a magnetic field for saturating the sample S is applied in the positive direction of the Y axis by the quadrupole electromagnet device 6, and the saturation magnetic field application image YR _MS is It is the captured image acquired in the state which applied the magnetic field which saturates S to the negative direction of the Y-axis.

  Note that the order in which steps S11 to S14 are executed is arbitrary.

Step S02:
Referring to FIG. 10 again, after step S01, observation image data, that is, an image when a magnetic field to be observed is applied to the sample S is acquired. FIG. 12 is a flowchart showing details of the observation image data acquisition in step S02. First, an X-direction observation image XF is acquired by observing in the positive direction of the X axis in a state where a magnetic field to be observed is applied (step S21). Furthermore, an X-direction observation image XR is acquired by observing in the negative direction of the X axis in a state where the magnetic field to be observed is applied (step S22). Furthermore, a Y-direction observation image YF is acquired by observing in the positive direction of the Y-axis with the magnetic field to be observed being applied (step S23). Furthermore, a Y-direction observation image YR is acquired by observing in the negative direction of the Y-axis with the magnetic field to be observed applied (step S24). Note that the order in which steps S21 to S24 are executed is arbitrary. In steps S21 to S24, the magnetic field to be observed may be zero.

  In this embodiment, observation image data is acquired (step S02) after acquisition of reference data (step S01), but the order may be reversed.

Step S03:
Referring to FIG. 10 again, after steps S01 and S02, the next four images: X-direction component image X (X-axis direction magnetization component image), Y-direction component image Y (Y-axis direction magnetization component) Image), Z-direction component image Zx (image of magnetization component in Z-axis direction) obtained from observation in the X-axis direction, and Z-direction component image Zy obtained from observation in Y-axis direction are calculated by arithmetic processing. Is done.

  FIG. 13 is a diagram showing an arithmetic process for calculating the X direction component image X, FIG. 14 is a diagram showing an arithmetic process for calculating the Y direction component image Y, and FIG. 15A is obtained from observation in the X direction. FIG. 15B is a diagram illustrating calculation processing for calculating a Z-direction component image from a captured image obtained from observation in the Y direction.

As shown in FIG. 13, the difference image (corresponding to the “incident from the left” image) between the X direction observation image XF and the saturation magnetic field application image XF _PS obtained by “observing in the positive direction of the X axis”. Further, a difference image (corresponding to an “incident from right” image) between the X direction observation image XR obtained by “observing in the negative direction of the X axis” and the saturation magnetic field application image XR _PS is calculated. . Further, a difference image (XF-XF _PS ) − (XR-XR _PS ) of these two difference images XF-XF _PS and XR-XR _PS is calculated as an X-direction component image X.

Similarly, as shown in FIG. 14, a difference image (“incident from the front” image) between the Y direction observation image YF and the saturation magnetic field application image YF _PS obtained by “observing in the positive direction of the Y axis”. Further, a difference image (corresponding to an “incident from behind” image) between the Y direction observation image YR and the saturation magnetic field application image YR _PS obtained by “observing in the negative direction of the Y axis” is calculated. Calculated. Further, a difference image (YF-YF _PS ) − (YR-YR _PS ) of these two difference images YF-YF _PS and YR-YR _PS is calculated as a Y-direction component image Y.

Further, as shown in FIG. 15A, a difference image XF-XF _PS (from the left side) between the X direction observation image XF obtained by “observing in the positive direction of the X axis” and the saturation magnetic field application image XF _PS. Equivalent to an “incident” image) and a difference image XR-XR _PS (“incident from right” image) between an X-direction observation image XR obtained by “observing in the negative X-axis direction” and a saturation magnetic field application image XR _PS (XF−XF _PS ) + (XR−XR _PS ) is calculated as the Z direction component image Zx.

Further, as shown in FIG. 15B, a difference image YF-YF _PS (from the front) between the Y-direction observation image YF obtained by “observing in the positive direction of the Y-axis” and the saturation magnetic field application image YF _PS. Equivalent ”image) and a difference image YR-YR _PS (“ incident from behind ”image) between the Y direction observation image YR obtained by“ observing in the negative Y-axis direction ”and the saturation magnetic field application image YR _PS (YF−YF _PS ) + (YR−YR _PS ) is calculated as the Z-direction component image Zy.

  Further, an average image (Zx + Zy) / 2 of these two Z direction component images Zx and Zy is calculated as an averaged Z direction component image Zavg.

In summary, the X-direction component image X, the Y-direction component image Y, the Z-direction component images Zx and Zy, and the averaged Z-direction component image Zavg are expressed by the following equations:
X = (XF-XF _PS ) − (XR-XR _PS ) (5a)
_{Y = (YF-YF PS)} - (YR-YR PS) ··· (5b)
Zx = (XF−XF _PS ) + (XR−XR _PS ) (5c)
Zy = (YF−YF _PS ) + (YR−YR _PS ) (5d)
Zavg = (Zx + Zy) / 2 (5e)

In the calculation of the X-direction component image X by the above arithmetic processing, the saturation magnetic field application image XF _PS and the saturation magnetic field application obtained as a saturated image in a state in which the sample S is saturated by applying a magnetic field in the positive direction of the X axis. Only the image XR _PS is used, but in addition to this, a saturation magnetic field application image XF _MS and a saturation magnetic field application image XF obtained by applying a magnetic field in the negative direction of the X axis to saturate the sample S. _MS may be used. In this case, the difference image XF− (XF _PS + XF) between the X direction observation image XF obtained by “observing in the positive direction of the X axis” and the average image of the saturation magnetic field application image XF _PS and the saturation magnetic field application image XF _{MS. MS} ) / 2 is calculated. Similarly, the difference image XR− (XR _PS + XR) between the X direction observation image XR obtained by “observing in the negative direction of the X axis” and the average image of the saturation magnetic field application image XR _PS and the saturation magnetic field application image XR _{MS. MS} ) / 2 is calculated. Further, a difference image {XF− (XF _PS + XF _MS ) / 2} − {XR− (XR _PS + XR _MS ) / 2} of these two difference images is calculated as the X direction component image X.

Similarly, in the calculation of the Y-direction component image Y, in addition to the saturation magnetic field application image YF _PS and the saturation magnetic field application image YR _PS obtained by applying a magnetic field in the positive direction of the Y axis and saturating the sample S, A saturated magnetic field application image YF _MS and a saturated magnetic field application image YR _MS obtained in a state where the sample S is saturated by applying a magnetic field in the negative direction of the Y axis may be used. In this case, the difference image YF− (YF _PS + YF) between the Y direction observation image YF obtained by “observing in the positive direction of the Y axis” and the average image of the saturation magnetic field application image YF _PS and the saturation magnetic field application image YF _{MS. MS} ) / 2 is calculated. Similarly, the difference image YR− (YR _PS + YR) between the Y direction observation image YR obtained by “observing in the negative direction of the Y axis” and the average image of the saturation magnetic field application image YR _PS and the saturation magnetic field application image YR _{MS. MS} ) / 2 is calculated. Further, a difference image {YF− (YF _PS + YF _MS ) / 2} − {YR− (YR _PS + YR _MS ) / 2} of these two difference images is calculated as the Y direction component image Y.

In this case, the Z direction component image Zx is calculated as an addition image {XF− (XF _PS + XF _MS ) / 2} + {XR− (XR _PS + XR _MS ) / 2}, and the Z direction component image Zy is an addition image. is calculated as _{{YF- (YF PS + YF MS} ) / 2} + {YR- (YR PS + YR MS) / 2}. Further, an average image (Zx + Zy) / 2 of these two Z direction component images Zx and Zy is calculated as an averaged Z direction component image Zavg.

In summary, the X-direction component image X, the Y-direction component image Y, the Z-direction component images Zx and Zy, and the averaged Z-direction component image Zavg may be calculated by the following equations:
X = {XF- (XF _PS + XF _MS ) / 2}-{XR- (XR _PS + XR _MS ) / 2}
... (6a)
_{Y = {YF- (YF PS +} YF MS) / 2} - {YR- (YR PS + YR MS) / 2}
... (6b)
Zx = {XF- (XF _PS + XF _MS ) / 2} + {XR- (XR _PS + XR _MS ) / 2}
... (6c)
_{Zy = {YF- (YF PS +} YF MS) / 2} + {YR- (YR PS + YR MS) / 2}
... (6d)
Zavg = (Zx + Zy) / 2 (6e)

  The calculated X-direction component image X, Y-direction component image Y, Z-direction component images Zx, Zy, and averaged Z-direction component image Zavg are displayed on the display device 5 so that the magnetization state of the sample S can be visually observed. can do.

Step S04:
Further, as shown in FIG. 10, the magnetization direction at each position of the sample S is calculated. In the calculation of the magnetization direction at each position of the sample S, the X normalized data x _NRM is calculated by normalizing the luminance data of the image of the magnetization component in the X-axis direction with the luminance data when the sample S is saturated. Further, the Y normalized data y _NRM is calculated by normalizing the luminance data of the image of the magnetization component in the Y-axis direction with the luminance data when the sample S is saturated. Specifically, the X normalized data x _NRM and the Y normalized data y _NRM are calculated by the following equations:
Here, ABS indicates an absolute value.

FIG. 16 shows that the X normalized data x _NRM and Y normalized data y _NRM obtained by the equations (7a) and (7b) are values corresponding to Mx / M and My / M in the equation (4). FIG. In the derivation of Equation (7a), an approximation is made that the luminance of the image obtained by “observation in the positive direction of the X axis” and “observation in the negative direction of the X axis” changes linearly with respect to Mx / M. ing. This approximation relies on the fact that the rotation angle of the polarization plane changes approximately linearly with respect to Mx / M, and the luminance data of the image changes approximately linearly with the rotation angle of the polarization plane. The saturation magnetic field application image XF _PS obtained from “observation in the positive direction of the X axis” when applying a magnetic field that saturates the sample in the positive direction of the X axis is an image in the case of Mx / M = 1.0. The saturation magnetic field application image XF _MS obtained from “observation in the positive direction of the X axis” when applying a magnetic field that saturates the sample in the negative direction of the X axis is an image in the case of Mx / M = −1.0. Therefore, the value of Mx / M (Mx / M) _F corresponding to the value of the luminance data of the X direction observation image XF obtained by “observing in the positive direction of the X axis” is expressed by the following formula (7c ) Is given by:

Similarly, the saturation magnetic field application image XR _PS obtained from “observation in the negative X-axis direction” when applying a magnetic field that saturates the sample in the positive X-axis direction is obtained when Mx / M = 1.0. The saturation magnetic field application image XR _MS obtained from “observation in the negative X-axis direction” when applying a magnetic field that saturates the sample in the negative X-axis direction is Mx / M = −1.0. Therefore, the value of Mx / M (Mx / M) _R in the luminance data value of the X direction observation image XR obtained by “observing in the negative direction of the X axis” is represented by the following formula ( Given in 7d):

The X normalized data x _NRM is calculated as an average value of (Mx / M) _F obtained by Expression (7c) and (Mx / M) _R obtained by Expression (7d).

Similarly, the Y normalized data y _NRM approximates that the luminance of the image obtained by “observation in the positive direction of the Y axis” and “observation in the negative direction of the Y axis” changes linearly with respect to My / M. Based on the following average values of (My / M) _F and (My / M) _R obtained by the following formulas (7e) and (7f):

Further, the Z normalized data z _NRM is _expressed by the following equation (8) corresponding to the above equation (4):
Is calculated by Since the X normalized data x _NRM and the Y normalized data y _NRM are values corresponding to Mx / M and My / M in Equation (4), respectively, the Z normalized data z _NRM is equivalent to Mz / M. The value to be Although the Z normalized data z _NRM obtained by Expression (8) has positive / negative indefiniteness, the positive / negative of the Z normalized data z _NRM can be determined from the brightness of the image of the magnetization component in the Z-axis direction.

By the above calculation, the unit vector M _NRM of the magnetization direction at each position of the sample S is _expressed by the following formula:
M _NRM = (x _NRM , y _NRM , z _NRM ) (9)
It will be obtained as.

(Magnetic transfer using Faraday media)
In the calculation of the magnetization direction described above, the rotation of the polarization plane due to the Kerr effect that appears due to the magnetization of the magnetic material is used, but by performing magnetic transfer using a medium (Faraday medium) that exhibits the Faraday effect. Generate images of the X-axis component, Y-axis component, and Z-axis component of the magnetic field at the position of the medium, or calculate the values of the X-, Y-, and Z-axis components, respectively. can do.

  FIG. 17A is a diagram for explaining magnetic transfer using the Faraday medium 71, and FIG. 17B is a perspective view showing an example of the structure of the Faraday medium 71. As illustrated in FIG. 17B, the Faraday medium 71 includes a Faraday glass 72 (for example, FR-5 Faraday glass) that exhibits a Faraday effect, and a reflective film 73 formed on the Faraday glass 72. Instead of the Faraday glass 72, a transparent substrate on which a Bi: YIG thin film is formed may be used. In this case,

  When it is desired to measure a spatial magnetic field generated by a certain magnetic field generation source 80 (for example, a coil), the Faraday medium 71 is arranged in a spatial region where the magnetic field is to be measured. Then, as shown in FIG. 17A, for the Faraday medium 71, the four observations described above: “observation in the positive direction of the X axis” “observation in the negative direction of the X axis” “in the positive direction of the Y axis” “Observation” and “observation in the negative direction of the Y-axis” are performed. Incident light is incident on the surface of the Faraday glass 72 opposite to the surface on which the reflective film 73 is formed. “Observation in the positive direction of the X-axis”, “Observation in the negative direction of the X-axis”, “Observation in the positive direction of the Y-axis” and “Observation in the negative direction of the Y-axis” are, for example, the magnetic characteristics shown in FIG. Performed by the measuring device.

  The difference image XF-XR between the image XF obtained by “observing in the positive direction of the X axis” and the image XR obtained by “observing in the negative direction of the X axis” is an image of the X axis direction component of the magnetic field. Yes, the added image XF + XR of the images XF and XR is an image of the Z-axis direction component of the magnetic field. Similarly, the difference image YF-YR between the image YF obtained by “observing in the positive direction of the Y axis” and the image YR obtained by “observing in the negative direction of the X axis” is the Y-axis direction component of the magnetic field. The added image YF + YR of the images YF and YR is an image of the Z-axis direction component of the magnetic field. In such a method, two images of the Z-axis direction component of the magnetic field are obtained. However, the average image {(XF + XR) + (YF + YR)} / 2 of the addition image XF + XR and the addition image YF + YR may be used as the final image of the Z-axis direction component of the magnetic field.

  The luminance data of each pixel of the X-axis direction component image obtained by the magnetic field measurement method described above corresponds to the magnitude of the magnetic field in the X-axis direction at the corresponding position of the Faraday medium 71. Similarly, the luminance data of each pixel of the Y-axis direction component image corresponds to the magnitude of the magnetic field in the Y-axis direction at the corresponding position of the Faraday medium 71, and the luminance of each pixel of the Z-axis direction component image. The data corresponds to the magnitude of the magnetic field in the Z-axis direction at the corresponding position of the Faraday medium 71. Therefore, in principle, from the brightness data of each pixel of the image of the X-axis direction component, the Y-axis direction component, and the Z-axis direction component (or the data from which the brightness data is calculated), the Faraday medium The magnitudes of the X-axis direction component, the Y-axis direction component, and the Z-axis direction component of the magnetic field at each position 71 can be calculated.

  One problem is the correspondence between the actual magnitude of the Z-axis direction component Hz of the magnetic field and the luminance data of each pixel of the image of the Z-axis direction component Hz, and the X-axis direction components Hx and Y-axis directions of the magnetic field. The correspondence between the actual size of the component Hy and the luminance data of each pixel of the image of the X-axis direction component Hx and the Y-axis direction component Hy is different. For example, even if the value of the luminance data of the specific pixel of the image having the Z-axis direction component Hz of the magnetic field is the same as the value of the luminance data of the specific pixel of the image having the X-axis direction component Hx of the magnetic field, The magnitude of the component Hz and the magnitude of the X-axis direction component Hx are not necessarily the same. Similarly, even if the value of the luminance data of the specific pixel of the image having the Z-axis direction component Hz of the magnetic field and the value of the luminance data of the specific pixel of the image having the Y-axis direction component Hy of the magnetic field are the same, The magnitude of the direction component Hz and the magnitude of the Y-axis direction component Hy are not necessarily the same.

  Therefore, in the present embodiment, using the calibration coefficient k representing the correspondence between the luminance data of the image of the X-axis direction component or the Y-axis direction component with respect to the unit magnetic field and the luminance data of the image of the Z-axis direction component with respect to the unit magnetic field, A component in each direction of the magnetic field at the specific position is calculated. Hereinafter, a method of obtaining the calibration coefficient k and further calculating the X-axis direction component Hx, the Y-axis direction component Hy, and the Z-axis direction component Hz of the magnetic field using the calibration coefficient k will be described.

  FIG. 18 is a flowchart showing a procedure for calculating the X-axis direction component Hx, the Y-axis direction component Hy, and the Z-axis direction component Hz of the magnetic field.

Step S30:
First, the calibration coefficient k is calculated. The calibration coefficient k is calculated in advance using a standard sample formed of a ferromagnetic material. Specifically, first, the image of the magnetization component in the X-axis direction, the magnetization component in the Y-axis direction, and the magnetization component in the Z-axis direction is applied to the standard sample by the procedure described above (steps S01 to S04 in FIG. 10). And the magnetization direction of each position of the standard sample is calculated. As described above, the X normalized data x _NRM and the Y normalized data y _NRM at each position of the standard sample are calculated by the above equations (7a) and (7b), and the Z normalized data z _NRM is Calculated by equation (8). Also, an image Zx of the magnetization component in the Z-axis direction obtained by observing in the X-axis direction (positive direction, negative direction), and the Z-axis direction obtained by observing in the Y-axis direction (positive direction, negative direction). The magnetization component image Zy and the averaged magnetization component image Zavg in the Z-axis direction are expressed by equations (5c) to (5e) or equations (6a) to (6e).

The calibration coefficient k at each position is expressed by the following formula (10) using the Z normalized data z _{NRM at the position} and the luminance data Zavg of the magnetization component image in the Z-axis direction:
k = z _NRM / Zavg (10)
Is calculated by Here, z _NRM is a value obtained from an image of the magnetization component in the X-axis direction and an image of the magnetization component in the Y-axis direction of the standard sample, and Zavg is an image of the magnetization component in the Z-axis direction of the standard sample. Therefore, the correspondence between the luminance data of the X-axis direction component or Y-axis direction component image with respect to the unit magnetic field and the luminance data of the Z-axis direction component image with respect to the unit magnetic field is represented. It should be noted that the above calibration factor k is a device-dependent parameter, and the same calibration factor k can be used for samples placed at the same position even if the materials are different.

Step S31:
Next, the Faraday medium 71 is disposed at a position where the magnetic field is desired to be measured, and further, an image (a prescribed magnetic field application image) is obtained when the prescribed magnetic field H _NRM is applied to the Faraday medium 71. In the present embodiment, description will be made assuming that the prescribed magnetic field H _NRM is 1.0 kOe. Note that the magnitude of the prescribed magnetic field H _NRM can be adjusted as appropriate. FIG. 19 is a flowchart showing details of acquisition of the prescribed magnetic field application image in step S31.

First, defined by observing the positive direction of the X-axis magnetic field applying image _XF + _{1k, XF -1k} is acquired (step S41). Here, as described above, “observation in the positive direction of the X axis” means that incident light is incident in an incident direction that is in a plane parallel to the XZ plane and includes a component in the positive direction of the X axis (see FIG. 2 means that incident light I _IN1 ) is incident to obtain a captured image. Here, the prescribed magnetic field application image XF _{+ 1K} is a captured image obtained by applying the prescribed magnetic field H _NRM to the Faraday medium 71 in the positive direction of the X axis by the quadrupole electromagnet device 6, and the prescribed magnetic field application image XF _{− 1K} is a captured image acquired in a state in which the prescribed magnetic field H _NRM is applied in the negative direction of the X axis.

Furthermore, provisions field applying image _XR + 1K by observing the negative direction of the X _{axis, XR -1K} is acquired (step S42). Here, as described above, “observation in the negative direction of the X axis” means that incident light is incident in an incident direction that is in a plane parallel to the XZ plane and includes a component in the negative direction of the X axis (see FIG. 2 means that incident light I _IN2 ) is incident to obtain a captured image. Here, the prescribed magnetic field application image XR _{+ 1K} is a captured image acquired in a state where the prescribed magnetic field H _NRM is applied in the positive direction of the X axis by the quadrupole electromagnet device 6, and the prescribed magnetic field application image XR- _1K is defined. It is the captured image acquired in the state which applied the magnetic field _HNRM to the negative direction of the X-axis.

Furthermore, provisions field applying image _YF + _{1K, YF -1K} is obtained by observing the positive direction of the Y-axis (step S43). Here, “observation in the positive direction of the Y-axis” means that a captured image is obtained by entering incident light in an incident direction that is in a plane parallel to the YZ plane and includes a component in the positive direction of the Y-axis. Means. The prescribed magnetic field application image YF _{+ 1K} is a captured image acquired in a state where the prescribed magnetic field H _NRM is applied in the positive direction of the Y axis by the quadrupole electromagnet device 6, and the prescribed magnetic field application image YF- _1K is the prescribed magnetic field. It is the captured image acquired in the state which applied _HNRM to the negative direction of the Y-axis.

Furthermore, provisions field applying image _YR + 1K by observing the negative direction of the _{Y-axis, YR -1K} is acquired (step S44). Here, “observation in the negative direction of the Y axis” refers to obtaining a captured image by entering incident light in an incident direction that is in a plane parallel to the YZ plane and includes a component in the negative direction of the Y axis. Means. The prescribed magnetic field application image YR _{+ 1K} is a captured image acquired in a state where the prescribed magnetic field H _NRM is applied in the positive direction of the Y axis by the quadrupole electromagnet device 6, and the prescribed magnetic field application image YR- _1K is the prescribed magnetic field. It is the captured image acquired in the state which applied _HNRM to the negative direction of the Y-axis.

  Note that the order in which steps S41 to S44 are executed is arbitrary.

Step S32:
Referring to FIG. 18 again, after step S31, observation image data, that is, an image when a magnetic field to be observed is applied to the Faraday medium 71 is acquired (step S32). FIG. 20 is a flowchart showing details of the observation image data acquisition in step S32. First, an X-direction observation image XFM is acquired by observing in the positive direction of the X axis in a state where a magnetic field to be observed is applied (step S51). Further, the X direction observation image XRM is acquired by observing in the negative direction of the X axis in a state where the magnetic field to be observed is applied (step S52). Furthermore, a Y-direction observation image YFM is acquired by observing in the positive direction of the Y-axis while applying the observation target magnetic field (step S53). Furthermore, a Y-direction observation image YRM is acquired by observing in the negative direction of the Y-axis with the magnetic field to be observed being applied (step S54). Note that the order in which steps S51 to S54 are executed is arbitrary.

  In this embodiment, observation image data acquisition (step S32) is performed after reference data acquisition (step S31), but the order may be reversed.

Step S33:
Referring to FIG. 18 again, after steps S31 and S32, the next four images: X-direction component image XM (image of X-axis direction component of magnetic field), Y-direction component image YM (X-axis direction component of magnetic field) Image), Z-direction component image ZMx (image of Z-axis direction component of magnetic field) obtained from observation in X-axis direction, and Z-direction component image ZMy obtained from observation in Y-axis direction are calculated by calculation processing (Step S33).

  FIG. 21 is a diagram illustrating an arithmetic process for calculating the X-direction component image XM, FIG. 22 is a diagram illustrating an arithmetic process for calculating the Y-direction component image YM, and FIG. 23A is obtained from observation in the X direction. FIG. 23B is a diagram illustrating a calculation process for calculating the Z direction component image ZMx from the captured image, and FIG. 23B is a diagram illustrating a calculation process for calculating the Z direction component image ZMy from the captured image obtained from the observation in the Y direction.

As shown in FIG. 21, the difference image (corresponding to the “incident from the left” image) between the X direction observation image XFM obtained by “observing in the positive direction of the X axis” and the prescribed magnetic field application image XF _{+ 1K.} Further, a difference image (corresponding to an “incident from right” image) between the X direction observation image XRM obtained by “observing in the negative direction of the X axis” and the prescribed magnetic field application image XR _{+ 1K} is calculated. . Further, a difference image (XFM−XF _{+ 1K} ) − (XRM−XR _{+ 1K} ) of these two difference images is calculated as the X direction component image XM.

Similarly, as shown in FIG. 22, a difference image (“incident from front” image) between the Y direction observation image YFM obtained by “observing in the positive direction of the Y axis” and the prescribed magnetic field application image YF _{+ 1K.} Further, a difference image (corresponding to an “incident from behind” image) between the Y direction observation image YRM obtained by “observing in the negative direction of the Y axis” and the prescribed magnetic field application image YR _{+ 1K} is obtained. Calculated. Further, a difference image (YFM−YF _{+ 1K} ) − (YRM−YR _{+ 1K} ) of these two difference images is calculated as the Y direction component image YM.

Further, as shown in FIG. 23A, a difference image XFM−XF _{+ 1K} (“from left to right” between the X direction observation image XFM obtained by “observing in the positive direction of the X axis” and the prescribed magnetic field application image XF _{+ 1K.} and equivalent) to the incident "image, the" difference image XRM-XR + 1K ₍ "incident from the right and negative to the observation" and X-direction observation image XRM obtained prescribed field applying image XR + _1K of X-axis "images (XFM-XF _{+ 1K} ) + (XRM-XR _{+ 1K} ) is calculated as the Z-direction component image ZMx.

Further, as shown in FIG. 23B, a difference image YFM−YF _{+ 1K} (“from the front” between the Y direction observation image YFM obtained by “observing in the positive direction of the Y axis” and the prescribed magnetic field application image YF _{+ 1K.} and equivalent) to the incident "image, the" incident from the difference image YRM-YR + 1K ₍ "behind the negative direction observation" and Y-direction observation image YRM obtained prescribed field applying image YR + _1K of Y-axis "images Equivalent image) (YFM-YF _{+ 1K} ) + (YRM-YR _{+ 1K} ) is calculated as the Z-direction component image ZMy.

  Further, an average image (ZMx + ZMy) / 2 of these two Z direction component images ZMx and ZMy is calculated as an averaged Z direction component image ZMavg.

In summary, the X-direction component image XM, the Y-direction component image YM, the Z-direction component images ZMx and ZMy, and the averaged Z-direction component image ZMavg are expressed by the following equations:
XM = (XFM-XF _{+ 1K} )-(XRM-XR _{+ 1K} ) (11a)
YM = (YFM-YF _{+ 1K} )-(YRM-YR _{+ 1K} ) (11b)
ZMx = (XFM-XF _{+ 1K} ) + (XRM-XR _{+ 1K} ) (11c)
ZMy = (YFM-YF _{+ 1K} ) + (YRM-YR _{+ 1K} ) (11d)
ZMavg = (ZMx + ZMy) / 2 (11e)

In the calculation of the X-direction component image XM by the above arithmetic processing, only the prescribed magnetic field application image XF _{+ 1K} and the prescribed magnetic field application image XR _{+ 1K} obtained in a state where the prescribed magnetic field is applied in the positive direction of the X axis are used. In addition to these, the prescribed magnetic field application image XF- _1K and the prescribed magnetic field application image XR- _1K obtained in a state where the sample S is saturated by applying a magnetic field in the negative direction of the X axis may be used. In this case, the "X-axis in the positive direction to the observation" obtained was X-direction observation image XFM, difference image XFM- _{(XF + 1K} and the average image of defined magnetic field applying image _{XF + 1K} the prescribed field applying image _{XF -1K} + XF- _1K ) / 2 is calculated. Similarly, the X-direction observation image XRM obtained by "observed in the negative direction of the X axis", the differential image XRM- _{(XR + 1K} of the prescribed field applying image _{XR + 1K} and the average image of defined magnetic field applying image _{XR -1K} + XR- _1K ) / 2 is calculated. Furthermore, these difference images of two difference images _{{XFM- (XF + 1K + XF} -1K) / 2} - are _{{XRM- (XR + 1K + XR} -1K) / 2}, is calculated as the X-direction component image X.

Similarly, in the calculation of the Y-direction component image Y, in addition to the prescribed magnetic field application image YF _{+ 1K} and the prescribed magnetic field application image YF _{+ 1K} obtained with the prescribed magnetic field applied in the positive direction of the Y axis, A prescribed magnetic field application image YF _−1K and a prescribed magnetic field application image YR _−1K obtained in a state where a prescribed magnetic field is applied may be used. In this case, the "Y-axis in the positive direction to the observation" obtained was Y-direction observation image YFM, the difference image YFM- _{(YF + 1K} and the average image of the prescribed field applying image _{YF + 1K} defined field applying image _{YF -1K} + YF- _1K ) / 2 is calculated. Similarly, the Y-direction observation image YRM obtained by "observed in the negative direction of the Y-axis", the differential image YRM- _{(YR + 1K} of the prescribed field applying image _{YR + 1K} and the average image of defined magnetic field applying image _{YR -1K} + YR- _1K ) / 2 is calculated. Furthermore, these difference images of two difference images _{{YFM- (YF + 1K + YF} -1K) / 2} - are _{{YRM- (YR + 1K + YR} -1K) / 2}, is calculated as the Y-direction component image YM.

In this case, Z-direction component image ZMx is calculated as an addition image _{{XFM- (XF + 1K + XF} -1K) / 2} + {XRM- (XR + 1K + XR -1K) / 2}, Z -direction component image ZMy is added is calculated as an image _{{YFM- (YF + 1K + YF} -1K) / 2} + {YRM- (YR + 1K + YR -1K) / 2}. Further, an average image (ZMx + ZMy) / 2 of these two Z direction component images ZMx and ZMy is calculated as an averaged Z direction component image ZMavg.

In summary, the X-direction component image XM, the Y-direction component image YM, the Z-direction component images ZMx and ZMy, and the averaged Z-direction component image ZMavg may be calculated by the following equations:
XM = {XFM- (XF _PS + XF _MS ) / 2}-{XRM- (XR _PS + XR _MS ) / 2}
... (12a)
YM = {YFM- (YF _PS + YF _MS ) / 2}-{YRM- (YR _PS + YR _MS ) / 2}
... (12b)
ZMx = {XFM- (XF _PS + XF _MS ) / 2} + {XRM- (XR _PS + XR _MS ) / 2}
... (12c)
_{ZMy = {YFM- (YF PS +} YF MS) / 2} + {YRM- (YR PS + YR MS) / 2}
... (12d)
ZMavg = (ZMx + ZMy) / 2 (12e)

  By displaying the calculated X-direction component image XM, Y-direction component image YM, Z-direction component images ZMx, ZMy, and averaged Z-direction component image ZMavg on the display device 5, the X-axis direction component of the magnetic field, the Y-axis direction The component and the Z-axis direction component can be visually observed.

Further, as shown in FIG. 18, the X-axis direction component, the Y-axis direction component, and the Z-axis direction component of the magnetic field are calculated (step S34). Specifically, X normalized data X _NRM corresponding to the X-axis direction component of the magnetic field at each position and Y normalized data Y _NRM corresponding to the Y-direction component are calculated by the following equations:
Here, the equation (13a), in (13b), since X normalized data _{X NRM} and Y normalized data _{Y NRM} provisions magnetic field _{H NRM} (in the present embodiment 1 kOe) is standardized, the X standard The normalized data X _NRM and the Y normalized data Y _NRM are calculated as magnetic fields in units of kOe as they are.

FIG. 24 is a diagram for explaining that the X normalized data X _NRM and the Y normalized data Y _NRM obtained by the equations (13a) and (13b) are normalized by the specified magnetic field H _NRM . In the derivation of the expression (13a), an approximation that the luminance of the image obtained by “observation in the positive direction of the X axis” and “observation in the negative direction of the X axis” changes linearly with respect to Hx / H _NRM is an approximation. Has been made. Here, Hx is the X-axis direction component of the magnetic field. This approximation relies on the fact that the rotation angle of the polarization plane changes approximately linearly with respect to Hx / H _NRM , and the luminance data of the image changes approximately linearly with the rotation angle of the polarization plane. The prescribed magnetic field application image XF _{+ 1k} obtained from “observation in the positive direction of the X axis” when the prescribed magnetic field H _NRM is applied in the positive direction of the X axis is an image in the case of Hx / H _NRM = 1.0. The luminance data of the prescribed magnetic field application image XF _−1k obtained from “observation in the positive direction of the X axis” when the prescribed magnetic field H _NRM is applied in the negative direction of the X axis is Hx / H _NRM = −1.0. Therefore, the value of Hx / H _NRM (Hx / H _NRM ) _F corresponding to the luminance data value of the X direction observation image XFM obtained by “observing in the positive direction of the X axis”. Is given by the following equation (13c):

Similarly, the prescribed magnetic field application image XR _{+ 1k} obtained from “observation in the negative X-axis direction” when the prescribed magnetic field H _NRM is applied in the positive direction of the X-axis is obtained when Hx / H _NRM = 1.0. The luminance data of the prescribed magnetic field application image XR _−1k obtained from “observation in the negative direction of the X axis” when the prescribed magnetic field H _NRM is applied in the negative direction of the X axis is Hx / H _NRM = − Since it may be considered that the image is 1.0, the Hy / H _NRM value (Hy / H) corresponding to the luminance data value of the X direction observation image XRM obtained by “observing in the negative direction of the X axis” _NRM ) _R is given by the following formula (13d):

The X normalized data X _NRM is calculated as an average value of (Hx / H _NRM ) _F obtained by the equation (13c) and (Hy / H _NRM ) _R obtained by the equation (13d).

Similarly, the Y normalized data Y _NRM is an approximation that the luminance of the image obtained by “observation in the positive direction of the Y axis” and “observation in the negative direction of the Y axis” changes linearly with respect to Hy / H _NRM . Is calculated as an average value of (Hy / H _NRM ) _F and (Hy / H _NRM ) _R obtained by the following equations (13e) and (13f):

Further, the Z normalized data Z _NRM corresponding to the component in the Z-axis direction of the magnetic field at each position includes the luminance data of the averaged Z direction component image ZMavg calculated by the equation (11e) or the equation (12e), and the above equation. From the calibration coefficient k calculated in (10), the following formula (14) is calculated:
Z _NRM = k · ZMavg (14)
Since the Z normalized data Z _NRM is normalized by multiplying by the calibration coefficient k (= z _NRM / Zavg), the Z-axis direction component Z _NRM is also calculated as a magnetic field in units of kOe.

And more generalized, the provisions magnetic field _{H NRM,} the magnetic field in the X-axis direction component Hx, Y-axis direction component Hy, Z-axis direction component Hz of the formula (13a), (13b), _{X NRM} calculated by (14) , Y _NRM , Z _NRM may be used to calculate the following formula:
Hx = X _NRM · X _NRM (15a)
Hy = X _NRM · Y _NRM (15b)
Hz = X _NRM / Z _NRM (15c)
This completes the calculation processing for calculating the X-axis direction component, the Y-axis direction component, and the Z-axis direction component of the magnetic field.

  Although the embodiments of the present invention are specifically described above, the present invention should not be construed as being limited to the above-described embodiments. The present invention may be implemented with various modifications that will be apparent to those skilled in the art.

1: incident optical system 2: incident optical system 3: detection optical system 4: computing device 5: display device 6: quadrupole electromagnet device 7: incident light 8: reflected light 11: light source 12: condenser lens 15: collimator lens 16: Mirror 17: Movable mirror 18: Relay lens 19: Polarizer 21: Smith mirror 22: Half mirror 23: Objective lens 31: Analyzer 32: Imaging lens 33: Imaging device 61: Quadrupole electromagnet 63: Quadrupole electromagnet 65: Bipolar power supply 66: Bipolar power supply 71: Faraday medium 72: Faraday glass 73: Reflective film 80: Magnetic field generation source Hx: X-axis direction component Hy: Y-axis direction component Hz: Z-axis direction component _IIN1 : Incident light _IIN2 : Incident light _{I IN3:} incident light _{I IN4:} incident light _{I R1:} reflection light _{I R2:} reflection light theta _i: incidence angle theta _i1: incident angle theta _i2: ON Angular [theta] x: rotation angle [theta] y: Rotation angle [theta] z: rotational angle M: total magnetization _{M NRM:} unit vector Mx: magnetization component My: magnetization component Mz: magnetization component S: Sample X: X direction component image XF: X-direction observation image XFM : X direction observation image XF _MS : Saturation magnetic field application image XF _PS : Saturation magnetic field application image XM: X direction component image X _NRM : X axis direction component XR: X direction observation image XRM: X direction observation image XR _MS : Saturation magnetic field application Image XR _PS : Saturation magnetic field application image Y: Y direction component image YF: Y direction observation image YFM: Y direction observation image YF _MS : Saturation magnetic field application image YF _PS : Saturation magnetic field application image YM: Y direction component image Y _NRM : Y Axial direction component YR: Y direction observation image YRM: Y direction observation image YR _MS : Saturation magnetic field application image YR _PS : Saturation magnetic field application image ZMavg: Averaged Z direction Component image ZMx: Z direction component image ZMy: Z direction component image Z _NRM : Z-axis direction component Zavg: Averaged Z direction component image Zx: Z direction component image Zy: Z direction component image k: Calibration coefficient x _NRM : X standard Data Y _NRM : Y normalized data z _NRM : Z normalized data

Claims (20)

A light incident mechanism for making linearly polarized incident light incident on the sample;
An analyzer on which the reflected light obtained by reflecting the incident light on the sample is incident;
An imaging device that captures an image by imaging the signal light obtained by the reflected light passing through the analyzer; and
A magnetic characteristic measuring device comprising an arithmetic device,
The light incident mechanism is configured such that an incident direction in which the incident light is incident on the sample is variable,
When the light incident mechanism enters the linearly polarized first incident light into the sample in a first incident direction that is in the plane of the first incident surface and the incident angle is not 0 °, the imaging apparatus The first reflected light obtained by reflecting the first incident light by means of the first signal light obtained by passing through the analyzer, the first corresponding to the rotation angle of the polarization plane at each position of the sample. Get an image,
The sample is in a second incident direction such that the light incident mechanism has linearly polarized second incident light in the plane of the first incident surface and the incident angle is the same as the reflection angle of the first reflected light. The imaging device is configured to detect the second reflected light obtained by reflecting the second incident light by the sample and passing through the analyzer based on the second signal light. A second image corresponding to the rotation angle of the polarization plane at each position of
The arithmetic device is an image of a component in a first direction, which is an in-plane direction of the sample, of a magnetic physical quantity contributing to rotation of a polarization plane by calculating the first image and the second image. A magnetic characteristic measurement device that generates a one-component image and a second component image that is an image of a component of the magnetic physical quantity in a second direction that is a vertical direction of the sample. The magnetic property measuring apparatus according to claim 1,
The light incident mechanism applies linearly polarized third incident light to the sample in a third incident direction that is in the plane of the second incident surface perpendicular to the first incident surface and the incident angle is not 0 °. Based on the third signal light obtained when the third reflected light obtained when the third incident light is reflected by the sample and passes through the analyzer when the imaging device is incident, Acquiring a third image corresponding to the rotation angle of the polarization plane at each position;
In the fourth incident direction, the light incident mechanism causes the linearly polarized fourth incident light to be in the plane of the second incident surface, and the incident angle is the same as the reflection angle of the third reflected light. Based on the fourth signal light obtained when the fourth reflected light obtained by reflecting the fourth incident light by the sample passes through the analyzer when the imaging device is incident on the sample, Acquiring a fourth image corresponding to the rotation angle of the polarization plane at each position of the sample;
The calculation device calculates the component of the magnetic physical quantity in a third direction that is in the in-plane direction of the sample and is perpendicular to the first direction by calculating the third image and the fourth image. A magnetic characteristic measurement device that generates a third component image that is an image. The magnetic property measuring apparatus according to claim 2,
The arithmetic device generates a fourth component image that is an image of a component of the magnetic physical quantity in the second direction by calculating the third image and the fourth image. Magnetic property measuring device. The magnetic property measuring apparatus according to any one of claims 1 to 3,
The magnetic physical quantity is a magnetization at each position of the sample. The magnetic property measuring apparatus according to any one of claims 1 to 3,
The sample is a medium exhibiting a Faraday effect;
The magnetic physical quantity is a magnetic field at each position of the medium. It is a magnetic characteristic measuring apparatus of Claim 4, Comprising:
A first difference image that is a difference between the first image and a saturated image that is an image in a state where a magnetic field that saturates the sample is applied, and a second difference between the first image and the saturated image. A difference image with the difference image is generated as a first magnetization component image that is an image of the magnetization component in the first direction at each position of the sample,
A magnetic characteristic measurement device that generates an addition image of the first difference image and the second difference image as a second magnetization component image that is an image of a magnetization component in the second direction at each position of the sample. The magnetic property measuring apparatus according to claim 2 or 3,
The magnetic physical quantity is a magnetization at each position of the sample,
When the light incident mechanism applies linearly polarized fifth incident light to the sample in the first incident direction with a magnetic field that saturates the sample applied in the first direction, Corresponding to the rotation angle of the polarization plane at each position of the sample based on the fifth signal light obtained by the fifth reflected light obtained by reflecting the fifth incident light by the sample passing through the analyzer Get the fifth image,
In a state where a magnetic field that saturates the sample is applied in a fourth direction opposite to the first direction, the light incident mechanism enters linearly polarized sixth incident light into the sample in the first incident direction. Polarization planes at the respective positions of the sample based on the sixth signal light obtained when the fifth reflected light obtained when the fifth incident light is reflected by the sample passes through the analyzer. A sixth image corresponding to the rotation angle of
When the light incident mechanism injects linearly polarized seventh incident light into the sample in the second incident direction with a magnetic field that saturates the sample applied in the first direction, The seventh reflected light obtained by reflecting the seventh incident light by the sample corresponds to the rotation angle of the polarization plane at each position of the sample based on the seventh signal light obtained by passing through the analyzer. Acquire the seventh image,
When the light incident mechanism enters linearly polarized eighth incident light into the sample in the second incident direction with a magnetic field that saturates the sample applied in the fourth direction, Based on the eighth signal light obtained by the eighth reflected light obtained by reflecting the eighth incident light by the sample passing through the analyzer, it corresponds to the rotation angle of the polarization plane at each position of the sample. Acquire the 8th image,
The computing device includes a magnetization component in the first direction at each position of the sample from the first image, the second image, the fifth image, the sixth image, the seventh image, and the eighth image. A magnetic characteristic measuring device that calculates first normalized data corresponding to a ratio of total magnetization. The magnetic property measuring apparatus according to claim 7,
When the light incident mechanism applies linearly polarized ninth incident light to the sample in the third incident direction with a magnetic field that saturates the sample applied in the third direction, Corresponding to the rotation angle of the polarization plane at each position of the sample based on the ninth signal light obtained by the ninth reflected light obtained by reflecting the ninth incident light by the sample passing through the analyzer Get the ninth image,
When the light incident mechanism is incident on the sample in the third incident direction in the third incident direction with the magnetic field that saturates the sample applied in the fifth direction opposite to the third direction. Based on the tenth signal light obtained when the imaging device reflects the tenth incident light reflected by the sample and passes through the analyzer, the polarization plane at each position of the sample 10th image corresponding to the rotation angle of
When the light incident mechanism injects linearly polarized eleventh incident light into the sample in the fourth incident direction with a magnetic field that saturates the sample applied in the third direction, The eleventh reflected light obtained by reflecting the eleventh incident light by the sample passes through the analyzer and corresponds to the rotation angle of the polarization plane at each position of the sample. Get the 11th image,
In a state where a magnetic field for saturating the sample is applied in the fifth direction, when the light incident mechanism enters linearly polarized twelfth incident light into the sample in the fourth incident direction, the imaging device includes: Based on the twelfth signal light obtained when the twelfth reflected light obtained by reflecting the twelfth incident light by the sample passes through the analyzer, it corresponds to the rotation angle of the polarization plane at each position of the sample. Acquire the 12th image,
The arithmetic device includes a magnetization component in the third direction at each position of the sample from the third image, the fourth image, the ninth image, the tenth image, the eleventh image, and the twelfth image. A magnetic characteristic measuring device that calculates second normalized data corresponding to the ratio of total magnetization. The magnetic property measuring apparatus according to claim 8,
The arithmetic unit calculates third normalized data corresponding to the ratio of the magnetization component in the second direction and the total magnetization at each position of the sample from the first normalized data and the second normalized data. Magnetic property measuring device. Linearly polarized first incident light is incident on the sample in a first incident direction such that the first incident light is in the plane of the first incident surface and the incident angle is not 0 °;
Acquiring a first image corresponding to a rotation angle of a polarization plane at each position of the sample based on first reflected light obtained by reflecting the first incident light by the sample;
Entering linearly polarized second incident light into the sample in a second incident direction that is in the plane of the first incident surface and has the same incident angle as the reflection angle of the first reflected light When,
Obtaining a second image corresponding to the rotation angle of the polarization plane at each position of the sample, based on the second reflected light obtained by reflecting the second incident light by the sample;
A first component image that is an image of a component in a first direction that is an in-plane direction of the sample of a magnetic physical quantity that contributes to rotation of a polarization plane by calculating the first image and the second image; Obtaining a second component image which is an image of a component of the magnetic physical quantity in a second direction which is a vertical direction of the sample. The magnetic property measuring method according to claim 10,
Furthermore,
Linearly polarized third incident light is incident on the sample in a third incident direction that is in the plane of the second incident surface perpendicular to the first incident surface and the incident angle is not 0 °;
Acquiring a third image corresponding to the rotation angle of the polarization plane at each position of the sample, based on the third reflected light obtained by reflecting the third incident light by the sample;
Entering linearly polarized fourth incident light into the sample in a fourth incident direction that is in the plane of the second incident surface and has the same incident angle as the reflection angle of the third reflected light When,
Obtaining a fourth image corresponding to a rotation angle of a polarization plane at each position of the sample, based on fourth reflected light obtained by reflecting the fourth incident light by the sample;
By calculating the third image and the fourth image, a third magnetization that is an image of a component of the magnetic physical quantity in the third direction that is in the in-plane direction of the sample and is perpendicular to the first direction. A method for measuring magnetic properties, comprising: obtaining an image. The magnetic property measuring method according to claim 11,
Furthermore,
A method for measuring a magnetic characteristic, comprising: calculating a third component image that is an image of a component of the magnetic physical quantity in the second direction by calculating the third image and the fourth image. The magnetic property measuring method according to any one of claims 10 to 12,
The magnetic physical quantity is a magnetization at each position of the sample. The magnetic property measuring method according to any one of claims 10 to 12,
The sample is a medium exhibiting a Faraday effect;
The magnetic physical quantity is a magnetic field at each position of the medium. Placing a Faraday medium exhibiting a Faraday effect at a location where a magnetic field is measured;
Linearly polarized first incident light is incident on the Faraday medium in a first incident direction that is in the plane of the first incident surface and whose incident angle is not 0 °;
Acquiring a first image corresponding to a rotation angle of a polarization plane at each position of the Faraday medium based on first reflected light obtained by reflecting the first incident light by the Faraday medium;
The linearly polarized second incident light is incident on the Faraday medium in a second incident direction that is in the plane of the first incident surface and has the same incident angle as the reflection angle of the first reflected light. Steps,
Acquiring a second image corresponding to a rotation angle of a polarization plane at each position of the Faraday medium based on second reflected light obtained by reflecting the second incident light by the Faraday medium;
By calculating the first image and the second image, a first magnetic field component image that is an image of a magnetic field component in a first direction that is an in-plane direction of the Faraday medium, and a first magnetic field component image that is perpendicular to the Faraday medium. Obtaining a second magnetic field component image that is an image of magnetic field components in two directions. The magnetic field measurement method according to claim 15,
Furthermore,
Linearly polarized third incident light is incident on the Faraday medium in a third incident direction that is in a plane of a second incident surface perpendicular to the first incident surface and whose incident angle is not 0 °; ,
Acquiring a third image corresponding to a rotation angle of a polarization plane at each position of the Faraday medium based on third reflected light obtained by reflecting the third incident light by the Faraday medium;
The linearly polarized fourth incident light is incident on the Faraday medium in a fourth incident direction that is in the plane of the second incident surface and has the same incident angle as that of the third reflected light. Steps,
Obtaining a fourth image corresponding to a rotation angle of a polarization plane at each position of the Faraday medium based on fourth reflected light obtained by reflecting the fourth incident light by the Faraday medium;
By calculating the third image and the fourth image, a third magnetic field component image that is an image of a magnetic field component in a third direction that is in-plane direction of the Faraday medium and perpendicular to the first direction is obtained. A magnetic field measuring method comprising: obtaining a magnetic field. The magnetic field measurement method according to claim 15,
Furthermore,
A magnetic field measurement method comprising: generating a fourth magnetic field component image that is an image of a magnetic field component in the second direction by calculating the third image and the fourth image. The magnetic field measurement method according to claim 17,
Furthermore,
When the linearly polarized fifth incident light is incident on the sample in the first incident direction in a state where a predetermined prescribed magnetic field is applied to the Faraday medium in the first direction, the fifth incident light is reflected by the Faraday medium. Obtaining a fifth image corresponding to the rotation angle of the polarization plane at each position of the Faraday medium, based on the fifth reflected light obtained by reflection;
When linearly polarized sixth incident light is incident on the Faraday medium in the first incident direction with the prescribed magnetic field applied to the Faraday medium in a fourth direction opposite to the first direction, the Faraday medium Obtaining a sixth image corresponding to the rotation angle of the polarization plane at each position of the Faraday medium, based on the sixth reflected light obtained by reflecting the sixth incident light;
When linearly polarized seventh incident light is incident on the Faraday medium in the second incident direction with the prescribed magnetic field applied to the Faraday medium in the first direction, the Faraday medium causes the seventh incident light to be incident on the Faraday medium. Obtaining a seventh image corresponding to the rotation angle of the polarization plane at each position of the Faraday medium based on the seventh reflected light obtained by reflection;
When the linearly polarized eighth incident light is incident on the Faraday medium in the second incident direction with the prescribed magnetic field applied to the Faraday medium in the fourth direction, the Faraday medium causes the eighth incident light to be Obtaining an eighth image corresponding to the rotation angle of the polarization plane at each position of the Faraday medium based on the eighth reflected light obtained by reflection;
From the first image, the second image, the fifth image, the sixth image, the seventh image, and the eighth image, the magnetic field component in the first direction and the prescribed magnetic field at each position of the Faraday medium. Calculating a first normalized data corresponding to the ratio. The magnetic field measurement method according to claim 18,
Furthermore,
When the linearly polarized ninth incident light is incident on the Faraday medium in the third incident direction with the prescribed magnetic field applied to the Faraday medium in the third direction, the Faraday medium causes the ninth incident light to be incident on the Faraday medium. Obtaining a ninth image corresponding to the rotation angle of the polarization plane at each position of the Faraday medium, based on the ninth reflected light obtained by reflection;
When the linearly polarized tenth incident light is incident on the Faraday medium in the third incident direction with the prescribed magnetic field applied to the Faraday medium in the fifth direction opposite to the third direction, the Faraday medium Acquiring a tenth image corresponding to a rotation angle of a polarization plane at each position of the Faraday medium based on the tenth reflected light obtained by reflecting the tenth incident light; Eleventh reflected light obtained by reflecting the eleventh incident light by the Faraday medium when the eleventh incident light of linearly polarized light is incident on the Faraday medium in the fourth incident direction with the third direction applied. Obtaining an eleventh image corresponding to the rotation angle of the polarization plane at each position of the Faraday medium,
When the linearly polarized twelfth incident light is incident on the Faraday medium in the fourth incident direction in a state where a magnetic field for saturating the Faraday medium is applied in the fifth direction, the twelfth incident light is reflected by the Faraday medium. Obtaining a twelfth image corresponding to the rotation angle of the polarization plane at each position of the Faraday medium, based on the twelfth reflected light obtained by reflection;
From the third image, the fourth image, the ninth image, the tenth image, the eleventh image, and the twelfth image, the magnetic field component in the third direction and the prescribed magnetic field at each position of the Faraday medium. Calculating a second normalized data corresponding to the ratio. The magnetic field measurement method according to claim 18 or 19,
Furthermore,
The ratio between the magnetic field component in the second direction and the specified magnetic field at each position of the Faraday medium, based on an average image that is an average of the second magnetic field component image and the fourth magnetic field component image and a calibration coefficient acquired in advance. A magnetic field measurement method comprising the step of calculating third normalized data corresponding to.