JPH0390877A - Vector physical quantity distribution measuring device and its measuring method - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic field distribution measurement device, and particularly to a three-dimensional magnetic field measurement device that rapidly changes in a minute region of the order of 1 micron, such as the leakage magnetic field of a magnetic head. The present invention relates to a device Vt suitable for measuring distribution and a method of measurement.

[Conventional technology]

Magnetic disk devices for computers, magnetic tape devices and VT
There has been a remarkable progress in increasing the density of magnetic recording devices such as R, and there is a demand for higher performance magnetic heads used in these devices. In order to achieve high density magnetic recording, a narrow track magnetic head with a steep recording magnetic field distribution is required. As the track width decreases, writing on adjacent tracks due to leakage magnetic field in the track width direction of the magnetic head becomes a problem, and there is a need to develop a head with a small leakage magnetic field in the track width direction. In order to develop a head suitable for such high-density recording, it is important to develop an apparatus that can precisely measure the distribution of the recording magnetic field generated from the head.

A method of measuring the distribution of the recording magnetic field of a magnetic head is to make an electron beam incident near the gap of the magnetic head, and to measure the magnetic field distribution by utilizing the fact that the electron beam is bent by the Lorentz force caused by the magnetic field. It has been known.

In order to measure the three-dimensional distribution of a magnetic field, an electron beam is scanned while rotating a sample that generates a magnetic field, the amount of deflection of the electron beam by the magnetic field is stored in a computer, etc., and this data is calculated. A method is used to reconstruct the original magnetic field distribution. An example of attempting to measure such a three-dimensional magnetic field distribution is No. 491! ! l Japan Society of Applied Physics Academic Lecture Proceedings p55
9 (October 1988), and I.E.
E-Transaction On Magnetics, M
N.G. 21, (1985) pp. 1593-1
595 pages (It<OH, 1°rans.

Magnetiass, MAG21. (1985)
pp 1593-1595).

[Problem to be solved by the invention]

However, the above example does not describe a specific method for reconstructing the magnetic field distribution based on measured data.

In particular, in the above-mentioned measurements, it is difficult to configure the magnetic field component in the direction perpendicular to the rotational axis of the sample by ++f using conventional methods, and a method has been established to reconstruct the three-dimensional distribution of the magnetic field from the measurement data. , and the development of an actual device for magnetic field distribution 81 equipped with such means has been rare.

[Means to solve the problem]

In the present invention, in order to reconstruct a three-dimensional magnetic field distribution from ill'l constant data, the magnetic field component is divided into a magnetic field component parallel to the rotating shelf of the sample and a magnetic field component perpendicular to the rotating axis, and the magnetic field perpendicular to the rotating axis is To reconstruct the components, a pin with rotation angle information added to the measurement data is used. This makes it possible to three-dimensionally reconstruct the magnetic field distribution for both components parallel to and on the axis of rotation. The magnetic field distribution measuring device f't used in the present invention will be described below.
We will describe the specific configuration and magnetic field distribution reconstruction method.

The first part shows the configuration of a magnetic field distribution measuring device used in the present invention. Installed in vacuum chamber 6? An electron beam 1 is generated from an electron gun 2 which is
Make it incident near . The electron beam deflected by the magnetic field generated by the sample reaches an electron beam position detector, and the amount of deflection of the electron beam according to the magnetic field is measured. 1l11
The constant data is stored in the data storage section. itl! During the I measurement, the electron beam scans the vicinity of the sample under the control of the electron beam scanning control section 5, and the sample stage equipped with a rotation/movement mechanism is rotated under the control of the sample movement and rotation control section. After completing the IJ4 determination, the reconstruction calculation section calculates the measurement data, and the reconstruction calculation results are displayed on the reconstruction result display section.The overall measurement and calculation of 0 or more is controlled by the overall control section. The overall control section, data storage section, reconstruction calculation section, and reconstruction result display section are constituted by one or more computers.

Figure 2 shows the principle of measurement. Magnetic head 7 as a sample
An electronic beat t11 is passed near the surface 9 facing the recording medium. The electron beam is deflected by a leakage magnetic field 10 generated near the gap 8, and the deflection ft d t and dl of the electron beam are measured by an electron beam position detector. Magnetic head facing recording medium 1 "2 perpendicular to n9"
The X axis is the direction facing the recording medium, and the y axis is the direction of the track width, and the sample is rotated around the two axes during lI4\, 1lIII. ! One turn.

In addition, the electron beam is scanned in the x-y plane direction to
Deflection amounts dt and dz are measured with respect to the 111 rotation angle U and the distance ig between the 101 rotation axis of the sample and the electron beam.

As described above, the measurement data is recorded in the data recorder, and after reconstruction calculation is performed in the reconstruction calculation section, the calculation result is displayed on the reconstruction result display section.

Next, a specific reconstruction method will be described. A magnetic field component Bx in the direction of the curve of the magnetic head facing the recording medium, that is, in the X direction, a magnetic field component By in the track width direction, that is, the
The electron beam is subjected to a Lorentz force by the magnetic field component perpendicular to the beam, and is deflected in a direction perpendicular to both the beam traveling direction and the magnetic field direction. , electron beam deflection amount X-ym
The directional component dt is expressed as a function of B2 as follows.

dl (s, θ) = e/(2mV)J' Bld
Q - (1) Here, e is the electron's waiting time, 1 m is the electron's length, and ■ is the electron's accelerating voltage. Breath is a traveling electron beam F
Equation (1) indicates that the beam deflection Md1 is proportional to the line integral along the electron beam at the position Bz through which the electron beam passes. On the other hand, the component d2 of the electron beam deflection amount in two directions is a function of 13X, B, and the angle θ formed between the
ysinlj)dff...(2)

In the present invention, in order to reconstruct the Hz magnetic field distribution from these measurement data, we utilize a computerized abortion imaging method (Computer + IOGR) developed in the field of medical equipment.
aphy; hereinafter abbreviated as C'r) is used.

Next, a method of reconstructing the Hz distribution using the C'1' method will be explained. As shown in FIG. 3, the electron beam e is incident in the 2=constant direction in which B2 is distributed. Let S be the distance between the origin of the sample and the electron beam, and θ be the angle between the X axis of the sample and the direction perpendicular to the electron beam. The measurement reconnaissance is Bz(xl
Since it is given by the integral of y), it can be expressed as follows.

...(3) [RHz] F+ θ) means 1 MM of Hz on the straight line specified by (s,,0), and is called Radon transformation of Bz.

The 2-dimensional Fourier transform is d2-
1 from the inversion formula of Fourier transform.

k3 z = F'! −” t° zBz

-(4)Xexp(2yc i 14(xc
osθ+y sinθ))lR1dRdθ...(5) On the other hand, if the -dimensional Fourier transform is expressed as FA.

[? '1RBZ](t# θ)"[h'zBzko(t, cosθ, t gin
θ)...(6) XIR161P(2ye i R・(xcosθ−y
sinθ))dRdθ...('I) (7) Leaving the equation aside, ×1 shaku1exp(2tc i R・(xcosO+ys
irl))d RXIRlexp(2tc i R(x
cos&+ysitl))d s d R...(11
) As mentioned above, instead of calculating the Fourier transform of equation (9), we use the weighting function g of equation (I2) calculated in advance and the measured value [
K B z] (s p 13 ) Q) M(:I
The method of integrating the Bz (convolution) is called the convolution method.Finally, the distribution of Bz is obtained by the inverse projective transformation of equation (8).

To actually perform reconstruction calculations using the above algorithm, each calculation formula is digitized. If the electron beam is scanned at intervals of d 1llJ and the scan number is m, then s =
It is expressed as m d. Further, if the sample is rotated by Δθ and the rotation number is n, then 0=nΔ0. Therefore, the constant value of 2111 is d](m, n).

1'( of equation (12) expressed as d dm , n )
Then, the function is found.

or to prevent ringing noise during reconfiguration.

(13) by modifying equation Use.

− next.

Convolution calculation corresponding to equation (11) is performed from the measured value [RBzl(md*nΔθ) and the weighting function 11 or gz.

Hz’ (kd, nΔO) m=-(M-1)/2 ...(15) Here, M is the number of electron beam scans.

Next, as shown in Fig. 4, the coordinates of x - y + r11 to be reconstructed are discretized at intervals of ε, and 0 is expressed as x=p and y=qε.
The value of Bz at point (p+q) when the rotation angle is nΔθ is determined as follows. As shown in Figure 4, (p*q
) from the point and find the distance #ls between this point of intersection and the origin. The value of Bz' at a position 5llll from the origin is determined by interpolation calculation from the value of 82 at the grid point of k adjacent to the intersection and +1.
'(pε.

From qε; nΔθ), the inverse projective transformation corresponding to equation (8)...
・(16) The distribution of B2 is obtained by calculating. Here, N is the number of rotation steps, and operations of 0 or more are collectively shown in FIG.

As described above, in a three-dimensional magnetic field distribution measuring device that uses an electron beam as a magnetic field detection means, the magnetic field component B2 parallel to the rotation of the sample can be reconstructed by using the C'r method algorithm described above. Realization uJ Noh. but,
As shown in equation (2), one measurement data is expressed as the sum of two independent unknown quantities Bx and By, so it is impossible to reconstruct Bx and By using the same algorithm as above.
It is Noh.

The inventors discovered that the magnetic field components Bx, By perpendicular to the axis of rotation of the sample
As a result of intensive study on the method for reconstructing the three-dimensional distribution of
By multiplying by og (j and calculating this using the above-mentioned CT method, Bx can be reconstructed, and s
It has been found that By can be reconstructed by multiplying in (+) and calculating.

The principle of the cow is shown below.

When determining the leakage magnetic field in space as in the magnetic field distribution measurement device Ft used in the present invention, the magnetomotive force of the coil, magnet, etc. that causes the magnetic field does not exist in the measurement area, and the second In the figure, it exists in the area of z and O. Therefore, the magnetic field distribution in the region Z>O, which is the measurement chamber Nil, is determined by the magnetomotive force existing in the region Z<O. As shown in Fig. 6, the position of contempt 0 (xo* y(l
Assuming that there is a unit magnetic pole at zo), the magnetic field at point p(X+y*z) where Z>O due to this magnetic pole is expressed as follows. Since the distribution of magnetomotive force in the region of Z<0 is represented by the distribution of positive and negative magnetic poles, the magnetic field distribution in the space of Z>0 is also represented by the superposition of the above magnetic fields. For the above magnetic field distribution, if we calculate the same Radon transformation as if we filled out equation (3).

[R,BxE(S.

θ) ...(19) l L< B y] (s e U) ...(20) becomes.

Here, C is C=ξ2+2ξ (sinxo-eos&yo)+s2-2 s (cosθxo+5inByo)+xo”+
yo”+(z+zo)” (21).

(19).

(20) are respectively [Bx] (s + U) [RHy] (SL - θ) where L) = s'' + 2s (xocos θ + yasirl)
+(xocosθ−yosin & )”+ x o”
10y o"+(Z + z o)"...(24) On the other hand, as shown in equation (2), the pipe that can actually be measured is
Since (B xcos B +B ysinθ),
The value obtained by multiplying this Radon conversion by CO8θ and sinθ is:
[K(Bxcosθ+Hysin&)](s, &)X
cosθ...(25) [E(Bxcos&+8ysirl)](s, θ)Xs
j, n.

...(26) As above, x−y+(ri magnetic field strength ?1llI
The value obtained by multiplying the constant state d2 by cos B is equal to the value of 'mIf&' of the magnetic field of the X component, and the value obtained by multiplying da by sin θ
The value multiplied by
By performing reconstruction calculations using the ' method, the three freezing distributions of Bx and By can be reconstructed by M or uj.

Although the two series of explanations have described the measurement of magnetic field distribution using an electron beam, the physical quantity to be measured does not necessarily have to be a magnetic field, and the means of measurement does not necessarily have to be an electron beam. With this method, it is possible to measure a three-dimensional distribution of vector quantities, which was previously impossible to measure.

The measuring device b't of the present invention includes a mechanism for measuring the sum of vector physical quantities along a straight line passing through at least an 81 constant area, and a mechanism for rotating the sample about an axis perpendicular to the +A'kA. a mechanism, a mechanism in which the straight line scans within the measurement area in a direction perpendicular to the rotation axis, and i! III. A mechanism is required to reconstruct the distribution of the original vector object β11 amount using all the data.

lI of the sample? In order to reconstruct the distribution of the vector physical quantities of the components parallel to the rotation axis, the mechanism for measuring the sum of the vector physical quantities described above must be used at least before Ke I! Fl It is necessary to have a function that determines the sum of vector physical quantities parallel to the k-axis as a+11. From this measured value, the three-dimensional distribution of the vector physical quantity of the component parallel to the axis of rotation is reconstructed by performing the calculation procedure of the computer section lambda reflection method described above in the mechanism for reconstructing the distribution of the vector physical quantity. It can be configured.

Reconstruction of the distribution of the vector physical quantity of the component perpendicular to the axis of rotation is not possible for any vector physical quantity.The magnetic scalar voluntarine U of space satisfies the following three-dimensional Laplace equation.

δ”LJ a”v a”u-++-=0
...(Z7)Bx2 δy'' a
The z2 magnetic field can be expressed as the gradient of the 1i11 scalar voluncial. Therefore, for the vector physical quantity expressed by the gradient of the scalar physical quantity that satisfies the cubic 1G Laplace square equation, the tree 9. Using the QIJ device and method, it is possible to measure the vector physical quantity VH3 of the component that is perpendicular to the rotation axis.

For this measurement, it is necessary that the measurement mechanism described above has a function that can add the sum of vector physical quantities of components perpendicular to the rotation axis by ft1l. Furthermore, if the measuring mechanism has a function of measuring a component perpendicular to a straight line, the mechanism for reconstructing the distribution of the vector physical quantity can be used to measure the component at right angles to the straight line.

Based on the value multiplied by the cosine cosθ of the angle 0 formed by 1llllx identified on the sample at right angles to the axis of rotation and the direction perpendicular to the straight line,
By performing the calculation procedure of the computer abrasion imaging method described above, it is possible to reconstruct the distribution of the vector physical quantity of the one-do row component in X#4. In addition, it is possible to reconstruct the distribution of vector physical quantities parallel to the axis y perpendicular to both the rotation axis and the If the mechanism has the function of measuring the vector physical quantity of the component parallel to the above-mentioned 1 line maintenance, the above-mentioned gun θ and cos & will have an inverse relationship, and the value obtained by multiplying the measured value by gin 13 will also be Based on the weight multiplied by cos B in the X-axis direction, y
It is possible to reconstruct the distribution of vector physical quantities of axial components.

(Example) In order to demonstrate that the method of the present invention can reconstruct the three-dimensional distribution of Bx=By, Bz with ease.

Theoretical magnetic field distribution generated by the magnetic head BxseBys
Regarding g Bzs, reconstruction calculations were performed using the method of the present invention, and the reconstructed magnetic field distributions Bxr, Byr+ Bzr were compared with the original theoretical magnetic field distribution. Theoretical magnetic field distribution is gap length 1.2 μm, h rack width 6 μm, gap depth 10
This is calculated for a μm magnetic head. First, set the gap center of the magnetic head having the above-mentioned theoretical magnetic field distribution to x=0. T-rack width center y=0. With the surface facing the recording medium as z=0 and the two axes as rotation axes, the interval Δθ=
The sample was rotated by IF5 in the range of -90° to 90° at 1° intervals, and the quotient of the distance Mz = 0.1 itm from the surface facing the recording medium was calculated by using an electron beam at intervals of d = 0, 2 p m and -1
Measured value d1 (m, n
), dz(m, n) is calculated based on equations (1) and (2) to the zeroth order.In addition, as shown in Figure 5, the measured value of dx is Using the CT method as it is, the measured value of dz is calculated by eos fJ and sin θ multiplied by the c'r method, and Bz and B, respectively.
The distribution of x and By was determined. The spacing of the grid points used for reconstruction is 0.2 μm, and the reconstruction range is x = −10
˜10 μm, y=−10 to 10 μm. In Figure 7 I
3, Figure 8 shows a comparison of the theoretical 6J & rise distribution of By, and Figure 9 shows a comparison of the A configuration magnetic field distribution of Bz. In each episode (
a) is the theoretical magnetic field distribution within the x-y curve of z = 0.1 μm, (b) is the reconstructed magnetic field distribution, (c) is (a), (b)
This figure shows a comparison between the theoretical magnetic field distribution and lIJ, and the constituent magnetic field distribution at y=constant order 1d. In Figures 7 and 9, the value of y in (C) is O, and in Figure 8, y = 3.0 μm.
It shows the distribution according to the tendency of

As shown in Figures 7 to 9, although there are some calculation errors in the reconstruction 6j & field distribution at the ends of the reconstruction range IJti and the peak values of By and Hz, overall it reproduces the theoretical magnetic field distribution very well. are doing.

In this example, the convolution method was used as the reconstruction calculation method, but reconstruction can be easily performed using other CT methods other than the convolution method. For example, (It
) of the equation x+
To! , l to perform inverse Fourier transform to obtain the result of equation (9), and then perform inverse projective transform using equation (8) as before to reconstruct the original distribution.

〔Effect of the invention〕

As described above, the present invention uses an electron beam to easily and accurately generate the three-dimensional distribution of the x, y, and z components of the leakage magnetic field generated by the magnetic core of a magnetic head, etc., or by a permanent magnet. It is clear that it can be measured.

4. Figure 1 of the explanation sheet on page 114 shows the magnetic field distribution measuring device used in the present invention h'/(1)
2 is a diagram showing the principle of measurement of the magnetic field distribution 8IQ determination device used in the present invention, and Figures 3 to 6 are conceptual diagrams explaining the method of reconstructing the magnetic field distribution of the present invention, Figure 7~
FIG. 9 is a graph comparing the magnetic field distribution constructed by 4++ according to the present invention and the original theoretical magnetic field distribution.

Top...electron beam, 2...electron gun, 3...objective lens, 4...sample stage, 5...sample, 6...
Vacuum chamber, 7... Magnetic head, 8... Gap, 9.
...Face the recording medium.

Engineering 0... Transmission magnetic elevation, 11... Electron beam displacement detector.

No. Cause eye ■ Taku figure ≠ figure Na 5 eye Bacteria 6 diagram Engraving of drawings (no changes to content) Engraving of drawings (changed in content t1) Engraving of drawings (no changes in content) B engineering (Ding Engraving of drawings (content = no changes) Clean IF of the drawing (no change in content) Engraving of drawings (no changes to content) By(T) Engraving of drawings (no changes to content) 8 engravings (contents have changed) Bottom of the drawing + w (no fourth part in the content) β2 (T)

Claims (1)

[Scope of Claims] 1. An apparatus for measuring a three-dimensional distribution of vector physical quantities generated by a sample, including a mechanism for measuring the sum of vector physical quantities along a straight line that passes through at least a measurement area, and a mechanism that measures the sum of vector physical quantities along a straight line that passes through a measurement area, and a mechanism that measures the sum of vector physical quantities along a straight line that passes through a measurement area, and a mechanism that measures the sum of vector physical quantities along a straight line that passes through a measurement area; It has a mechanism for rotating around an axis of rotation, a mechanism for causing the straight line to scan within the measurement area in a direction perpendicular to the axis of rotation, and a mechanism for calculating the measured data and reconstructing the original distribution of vector physical quantities. , the mechanism for reconstructing the vector physical quantities has at least a means for realizing a calculation procedure of computer tomography, and the mechanism for measuring the sum of the vector physical quantities along the straight line has at least:
A mechanism having a function of measuring the sum along a straight line of components of vector physical quantities parallel to the rotation axis and reconstructing the distribution of the vector physical quantities calculates the vector parallel to the rotation axis from the measured values. 1. An apparatus for measuring components of a vector physical quantity, comprising means for reconstructing the distribution of components of the physical quantity. 2. An apparatus for measuring the three-dimensional distribution of vector physical quantities generated by a sample, which includes a mechanism for measuring the sum of vector physical quantities along at least a straight line passing through the measurement area, and a mechanism for rotating the sample around an axis perpendicular to the straight line. It has a mechanism for rotating, a mechanism for causing the straight line to scan the area to be measured in a direction perpendicular to the axis of rotation, and a mechanism for calculating the measured data and reconstructing the distribution of the original vector physical quantity. The constituting mechanism has at least a means for realizing a calculation procedure of computerized tomography, and the vector physical quantity is a quantity expressed by a gradient of a scalar physical quantity satisfying a three-dimensional Laplace equation, and The mechanism for measuring the sum of the vector physical quantities along the straight line has a function of measuring the sum of the components of the vector physical quantities along the straight line perpendicular to the straight line and perpendicular to the rotation axis, and a mechanism for reconstructing at least a means for multiplying the measured value by a cosine cos θ of an angle θ formed by an axis x fixed to the sample perpendicular to the rotation axis and a direction perpendicular to the straight line;
and means for multiplying the measured value by the sine sin θ of the angle θ, reconstructing the distribution of the vector physical quantity of the component parallel to the x-axis from the value multiplied by the cos θ, and
A vector physical quantity distribution measuring device comprising means for reconstructing a vector physical quantity distribution of a component parallel to an axis y perpendicular to both the rotation axis and the axis x from a value multiplied by . 3. In an apparatus that uses the principle that an electron beam is deflected by the presence of a magnetic field to measure the three-dimensional distribution of the magnetic field generated by a magnetic core or magnet, at least the sample is rotated about an axis perpendicular to the electron beam. It has a mechanism that allows the electron beam to scan within the measurement area in a direction perpendicular to the rotation axis, a mechanism that measures the amount of deflection of the electron beam, and a mechanism that reconstructs the magnetic field distribution even after calculating the measurement data. , the mechanism for reconstructing the magnetic field distribution has at least means capable of realizing a calculation procedure of computer tomography, and
A magnetic field distribution measuring device comprising means for reconstructing a magnetic field distribution of a component parallel to the rotation axis of the sample from a measured value of the deflection amount of the electron beam of the component perpendicular to the rotation axis of the sample. 4. In an apparatus that uses the principle that an electron beam is deflected by the presence of a magnetic field to measure the three-dimensional distribution of the magnetic field generated by a magnetic core or permanent magnet, at least the sample is rotated about an axis perpendicular to the electron beam. a mechanism in which the electron beam scans the area to be measured in a direction perpendicular to the axis of rotation, a mechanism in which the amount of deflection of the electron beam is measured, and a mechanism in which the measured data is calculated to reconstruct the original magnetic field distribution. , and the mechanism for reconstructing the magnetic field distribution has at least means capable of realizing a calculation procedure of computer tomography, and has a mechanism for reconstructing the magnetic field distribution, and has a means for realizing at least a calculation procedure of computer tomographic imaging, and has a mechanism for reconstructing the magnetic field distribution, and has a means for realizing a calculation procedure of at least a computerized tomography method, and has a mechanism for reconstructing the magnetic field distribution, and has a means for realizing a calculation procedure of at least a computerized tomography method, and has a mechanism for reconstructing the magnetic field distribution. , a means for multiplying the angle θ formed by an axis x fixed to the sample at right angles to the rotation axis and a cosine cos θ of the angle θ, and a means for multiplying the deflection amount measurement value by the sine s
comprises means for multiplying by nθ, reconstructs the magnetic field distribution of the component parallel to the axis x from the value multiplied by the cosθ, and
A magnetic field distribution measuring device comprising means for reconstructing a magnetic field distribution of a component parallel to an axis y perpendicular to both the rotation axis and the axis x from a value multiplied by inθ. 5. A method of measuring the three-dimensional distribution of the magnetic field generated by a magnetic core or magnet using the principle that an electron beam is deflected by the presence of a magnetic field, which includes at least rotating the sample and moving the electron beam within the area to be measured. an operation of scanning in a direction perpendicular to the rotation axis, an operation of measuring the amount of deflection of the electron beam, and an operation of calculating the measured data to reconstruct the original magnetic field distribution, and an operation of reconstructing the magnetic field distribution. includes at least a calculation operation of computer tomography imaging, and the calculation operation reconstructs the magnetic field distribution of the component parallel to the rotation axis of the sample from the measured value of the deflection amount of the electron beam of the component perpendicular to the rotation axis of the sample. A method for measuring magnetic field distribution characterized by: 6. A method of measuring the three-dimensional distribution of the magnetic field generated by a magnetic core or magnet by utilizing the principle that an electron beam is deflected by the presence of a magnetic field, which involves at least rotating the sample and moving the electron beam within the area to be measured. an operation of scanning in a direction perpendicular to the rotation axis, an operation of measuring the amount of deflection of the electron beam, and an operation of calculating the measured data to reconstruct the original magnetic field distribution, and an operation of reconstructing the magnetic field distribution. includes at least a calculation operation of computerized tomography imaging, and includes a measurement value of the deflection amount of the electron beam of a component parallel to the rotation axis of the sample, and a direction perpendicular to an axis x fixed to the sample at right angles to the rotation axis and the direction of the electron beam. the axis x
A magnetic field distribution characterized in that the magnetic field distribution of the component parallel to is reconstructed, and the magnetic field distribution of the component parallel to the axis y perpendicular to both the rotation axis and the axis x is reconstructed from the value multiplied by the sin θ. Measuring method.