JP2003057023A - Angle calibration apparatus using x-ray polyhedral mirror and angle calibration method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an angle calibration apparatus using an X-ray polyhedral mirror, and an angle calibration method using the same. SOLUTION: When the center axis of an X-ray polygon crystal 7 is set to [0, 1, -1] of a silicon single crystal, a surface index enabling geometric reflection becomes xhh and a large number of reflecting surfaces are obtained according to an extinction rule of X-ray diffraction of a diamond structure. Since a 110 axis is twice symmetry, these reflecting surfaces appear on an opposite side and, in this case, 340 reflecting surfaces in total can be utilized. Two orthogonal reflecting surfaces in the X-ray polygon crystal 7 are set so as to be made parallel to two posture adjusting tilt stages 5 and the center is allowed to coincide with the center of a rotary table 8 by an XY stage 5 and the reflection of X-rays is utilized to adjust the center line of the X-ray polygon crystal 7 so as to make the same parallel to the axis of the rotary table 8 so that the center line is almost overlapped with the axis of the rotary table 8. When the X-ray polygon crystal 7 after adjustment is rotated, Bragg reflection is successively generated and the position of a Bragg angle can be determined by a reflection intensity curve caught by an X-ray detector 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angle calibration device using an X-ray polygonal mirror (X-ray polygon) and an angle calibration method using the same.

[0002]

BACKGROUND OF THE INVENTION Visible light polygons as a basis for angle measurements are a very easy tool to use when calibrating the angular position of a device such as a precision index table. JIS
The more it is taken up by the standard B7432, the more important it is in practical use.

[0003]

However, since such a visible light polygon is an optical product, there is a processing error. From the viewpoint of calibrating the angle of the rotary table, a polygon with as many faces as possible is preferable, but due to the limit of precision processing, an optical polygon with an effective reflection mirror area of 10 mm diameter and a compact size of 36 faces or more is recommended. I can't quite hope for it.

Further, when the angular position is calibrated by using the optical polygon, an optical autocollimator is also used, but due to the influence of the fluctuation of the air, the limit of the verification accuracy is about 1 arcsecond. Therefore, the standard angle calibration method using the optical polygon cannot meet the demand of advanced research in terms of both the number of angular positions that can be measured at one time and the accuracy that can be reached.

However, the above situation is completely changed by replacing the reflection of visible light with the diffraction of X-rays and replacing the plane optical mirror with the atomic arrangement of perfect crystals. For example, using a cylindrical X-ray polygon having a silicon single crystal [0,1, -1] as an axis, when the X-ray wavelength is 0.7Å, there are 170 measurable reflecting surfaces {hkk}, From the two-fold symmetry of, 340 clockwise and counterclockwise reflections are observed. That is, far more can be selected than artificial optical polygons, and on average, one angular position can be calibrated every 1.1 degrees. Also, if shorter wavelengths are used, the number of reflective surfaces will increase. Furthermore, there is no influence of air fluctuations, and high measurement accuracy can be obtained even in the atmosphere.

[0006] From the "reckless" measurement such as the time dependence of physical constants to the "common sense" measurement such as the slow strain relaxation process of a material crystal and the impurity diffusion mechanism in the crystal at low temperature To compare two things with space separated by space, you cannot avoid absolute measurement. However, while highly accurate absolute measurement is important for the evaluation of substances, it is a very labor-intensive task and is often avoided.

Accurate and precise measurement of angles is a
It is extremely important for the material evaluation method using line diffraction. The wavelength λ of the X-ray, the crystal lattice parameter d, and the diffraction angle θ are connected by the Bragg formula. If the X-ray wavelength and the angle of diffraction are known during material evaluation, the lattice spacing d related to the physical properties can be known. It is relatively easy to know the absolute value of the X-ray wavelength up to 7 to 8 digits experimentally, but the angle accuracy of a precision index table with a complicated mechanism is always a problem, and it balances with the effective value of the wavelength. Absent. This is because the precision index table usually has a rotary encoder attached to it, but the standard organization guarantees that it is a single encoder, not the entire rotary table incorporating it.

Further, even if the reading of the angular position by the encoder of the device is sufficiently reliable, there is no guarantee that it will be semi-permanently accurate as long as it is a device.
Therefore, for material science research that requires absolute measurement of X-ray diffraction, a highly accurate angular position of the rotary table device (accuracy of about 0.1 arcsecond over the entire circumference, and a relative value of 1)
A calibration method of 0 ^-7 ) is essential.

In view of the above situation, the present invention is compact and can measure the angle accurately and precisely.
An object is to provide an angle calibration device using a line polygon mirror and an angle calibration method using the same.

[0010]

In order to achieve the above-mentioned object, the present invention uses X-rays instead of visible light, and uses a perfect crystal diffraction grating surface instead of an optical reflecting surface. . The angle formed by the diffraction planes of a perfect crystal is highly accurately determined by the symmetry of the crystal and the plane index. For X-rays of a specified wavelength, the angular position and angular width at which the reflection occurs can be completely predicted by the dynamic diffraction theory of X-rays.

First, assuming that the central axis of the X-ray polygon crystal is [0, 1, -1] of the silicon single crystal, the geometrically reflective surface index is xhh, and according to the extinction rule of X-ray diffraction. , A large number of reflective surfaces can be obtained. Since the 110 axis is 2-fold symmetric, these reflections are also seen on the opposite side, so in this case a total of 340 reflecting surfaces are available. The separated monochromatic X-ray beam is spread by the X-ray collimator, and a beam size that allows the X-ray polygon crystal to be fully bathed is obtained, while the divergence angle is suppressed to less than a second. The two orthogonal reflecting surfaces in the X-ray polygon crystal are placed parallel to the two attitude adjustment tilt tables, and the center line of the X-ray polygon crystal is parallel to the axis of the rotary table by using the X-ray reflection. So that the axis of the rotary table is approximately overlapped with the xy stage. If you turn the adjusted X-ray polygon crystal, Bragg reflections will occur one after another,
The position of the Bragg angle can be determined by the reflection intensity curve captured by the X-ray detector. Correcting the temperature difference and refracting the X-ray of the X-ray polygonal crystal gives a correct geometric angle of 340.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of an angle calibrating apparatus using an X-ray polygon mirror showing an embodiment of the present invention, and FIG.

In this figure, 1 is an X-ray light source, 2 is an X-ray spectroscope (constant wavelength high resolution monochromator), 3 is an X-ray collimator, 4 is an X-ray slit, and 5 is a position adjusting XY stage (hereinafter, simply XY stage), 6 is a posture adjustment tilt stage (hereinafter, simply referred to as a tilt stage), 7
Is an X-ray polygon mirror (X-ray polygon crystal), 8 is a rotary table with a rotary encoder (hereinafter, simply referred to as a rotary table), 9 is a wide-angle X-ray detector, 10 is an electronic counter, 11 is a temperature sensor, and 12 is a temperature. The control device, 13 is the X-ray exit.

Here, as the X-ray light source 1, an X-ray tube that produces X-rays, radiant light, or the like is used. X-ray spectrometer 2
An X-ray beam having a specific wavelength is cut out from the linear light source 1. X
The line collimator 3 uses asymmetric reflection of X-rays,
It reduces the divergence of the monochromatic X-ray beam and at the same time widens the X-ray beam size in the scattering plane. The X-ray polygon crystal 7 has a thin cylindrical shape (several meters) in the upper half part cut out from the perfect crystal.
m diameter), with a thicker polyhedral single crystal (about 10 mm square) on the lower half foundation, the total height is 30 mm
It is a degree. The tilt stage 6 is an adjusting mechanism for making the center line of the X-ray polygon crystal 7 parallel to the axis of the rotary table 8. The rotary table 8 is an object to be calibrated , and X
Causes line diffraction. The wide-angle X-ray detector 9 records the X-ray diffraction intensity. The temperature sensor 11 monitors the temperatures of the X-ray spectroscope 2, the X-ray collimator 3, and the X-ray polygon crystal 7, respectively.

The separated monochromatic X-ray beam is spread by the X-ray collimator 3 to obtain a beam size that can be irradiated on the entire X-ray polygon crystal 7, and the divergence angle is suppressed to a second or less, so that the X-ray polygon crystal 7 can be obtained. The two orthogonal reflecting surfaces of the inside are placed parallel to the two tilt stages 6, and the center line of the X-ray polygon crystal 7 is made parallel to the axis of the rotary table 8 by utilizing the reflection of X-rays. The X-ray polygon crystal 7 which has been adjusted and arranged so that the centers thereof are approximately overlapped with each other on the XY stage 5, and Bragg reflection occurs one after another, and the reflection captured by the wide-angle X-ray detector 9 is detected. The strength curve is used to determine the position of the Bragg angle.

When the central axis of the X-ray polygonal crystal 7 is [0,1, -1] of a silicon single crystal, the geometrically reflective surface index becomes xhh, which is in accordance with the extinction rule of X-ray diffraction of a diamond structure. Accordingly, Table 1 (Materials 1 to 30), Table 2 (Materials 31 to 64), Table 3 (Materials 65 to 98), Table 4 (Material 9)
9-132), Table 5 (Materials 133-166), Table 6 (Materials 167-200), Table 7 (Materials 201-234), Table 8 (Materials 235-268), Table 9 (Materials 269-30).
2), Table 10 (Materials 303 to 336), Table 11 (Material 3)
37 to 340), a reflecting surface as shown in each column 1 is obtained.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

[0021]

[Table 4]

[0022]

[Table 5]

[0023]

[Table 6]

[0024]

[Table 7]

[0025]

[Table 8]

[0026]

[Table 9]

[0027]

[Table 10]

[0028]

[Table 11]

Assuming an X-ray wavelength of 0.7 nm, the respective Bragg angles are listed in columns 3 and 4. The geometrical position of each reflecting surface is column 5 and column 6.
Represented by. Since the 110 axis is 2-fold symmetric, these reflections are also seen on the opposite side, so in this example, a total of 340
A reflective surface is available.

The separated monochromatic X-ray beam is spread by the X-ray collimator 3 to obtain a beam size capable of irradiating the entire X-ray polygon crystal, while the divergence angle is suppressed to less than a second. The two orthogonal reflecting surfaces in the X-ray polygon crystal are
The tilt stage 5 is placed so as to be approximately parallel to it, and the center line of the X-ray polygon crystal 7 is adjusted to be parallel to the axis of the rotary table 8 by utilizing the reflection of X-rays so that they are approximately overlapped. By rotating the X-ray polygon crystal 7 that has been adjusted, Bragg reflections occur one after another, and the position of the Bragg angle can be determined by the reflection intensity captured by the X-ray detector 9. Correction of temperature difference and X of X-ray polygon crystal
Refraction corrections to the line yield 340 correct geometrical angular position coordinates.

FIG. 3 is a diagram showing the relationship between the reading angle of the rotary encoder of the rotary table according to the present invention and the accumulated error, and FIG. 4 is a diagram showing the relationship between the reading angle of the encoder according to the present invention and the error.

The method of calibrating the rotary table 8 using the X-ray polygonal mirror 7 is remarkably improved in both the number of calibratable angular positions and the accuracy as compared with the conventional method using a visible light polygon. By calibrating the entire apparatus including the rotary encoder attached to the rotary table 8, the accuracy and reliability of the apparatus can be improved. Since X-rays are used, there is no fluctuation in the refractive index with respect to visible light in the atmosphere, and highly accurate measurement can be performed in the atmosphere.

The mechanical adjustment according to the present invention will be described below.

(1) The separated monochromatic X-ray beam is spread by the X-ray collimator 3 to obtain a beam size that can irradiate the entire X-ray polygon crystal 7, and at the same time the divergence angle of the X-ray beam is less than a second. It can be suppressed.

(2) The rotary table 8 is installed so that its axis is orthogonal to the X-ray beam.

(3) The two orthogonal reflecting surfaces (for example, 100 and 011 directions; see FIG. 5) in the X-ray polygon crystal 7 are placed so as to be approximately parallel to the two tilt stages 5, and the X-ray reflection is used. Then, three or more sets of the tilt stage angular position and the position where X-ray reflection occurs are measured, the optimum tilt stage angular position is determined by quadratic curve fitting, and the center line of the X-ray polygon crystal 7 [0, 1, -1] is adjusted to be parallel to the axis of the rotary table 8 with a rotary encoder.

(4) On the XY stage 5, the center of the X-ray polygon crystal 7 is made to substantially coincide with the center of rotation of the rotary table 8.

(5) The window of the wide-angle X-ray detector 9 is installed at the same height as the X-ray beam.

The numerical processing is 0.06968n
A description will be given by taking a wavelength of m and silicon of 22.5 ° C.

The difference between the geometrical angular position of the reflecting surface (column 1) with respect to the reference surface (column 3) and the physical angular position at which the surface reflects X-rays (column 4) is calculated, and one number sequence is Columns 5 are obtained by rearranging the sequences in order of size. Taking into account the 2-fold symmetry, X
From the 170 reflecting surfaces of the line polygon crystal, 340 reflection angle positions can be obtained. The index and order are listed in column 1 and last column 8.

Obtained Sequence (Column 5) X0-X33
Reference numeral 9 is the order of X-ray reflection that occurs one after another when the crystal polygonal crystal 7 is rotated, and is corrected by refraction and temperature difference, and its angular position is a coordinate (column 6) that serves as a reference of the angle.

When the X-ray reflection occurs, the reading value of the rotary table 8 is Y0-Y339 (column 7).

Zi = Yi-Xi is an error (column 8)
Therefore, the reading of the encoder means the deviation from the true angular position.

An error (column 8) is obtained by subtracting the average offset amount from the data in column 8 from'Zi = Yi-Xi ', and the reading of the encoder means the deviation from the true angular position.

The cumulative error is obtained by Zi integration.

The present invention is not limited to the above embodiments, and various modifications can be made based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention.

[0047]

As described in detail above, according to the present invention, the following effects can be achieved.

Since X-rays are used, there is no fluctuation in the refraction of air, and because dynamic diffraction of X-rays in a perfect crystal is used, the angular positioning accuracy is 10 seconds from 1 second angle. It can be made more than double. Further, since the atomic arrangement of the perfect crystal is used, the X-ray polygon mirror can be obtained with high quality, compactness and low cost without being restricted by processing accuracy and shape. The number of faces that can be used is much larger than that of visible light, and in the case of commonly used 0.07 nm wavelength X-rays, it is possible to use the position of about 300 faces, and if the wavelength is made shorter,
Moreover, the number can be dramatically increased.

[Brief description of drawings]

FIG. 1 is a block diagram of an angle calibration device using an X-ray polygon mirror showing an embodiment of the present invention.

FIG. 2 is a configuration diagram of an angle calibration device using an X-ray polygon mirror showing an embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a reading angle of a rotary encoder of a rotary table according to the present invention and a cumulative error.

FIG. 4 is a diagram showing a relationship between a reading angle and an error of the encoder according to the present invention.

FIG. 5 is a diagram showing a plane position of an X-ray polygon crystal according to the present invention.

[Explanation of symbols]

1 X-ray light source 2 X-ray spectrometer (constant wavelength high resolution monochromator) 3 X-ray collimator 4 X-ray slit 5 Position adjustment XY stage 6 Posture adjustment tilt stage 7 X-ray polygon mirror (X-ray polygon crystal) 8 Rotary table with rotary encoder 9 Wide-angle X-ray detector 10 Electronics counter 11 Temperature sensor 12 Temperature control device 13 X-ray exit

Claims (3)

[Claims] 1. An (a) X-ray light source, (b) an X-ray spectrometer,
(C) X-ray collimator, (d) X-ray polygon mirror, (e)
Two attitude adjusting tilt stages that set up two orthogonal reflecting surfaces in the X-ray polygon mirror so as to be approximately parallel to each other;
(F) A precision rotation index in which the center line of the X-ray polygon mirror is adjusted to be parallel to the axis by using the xy stage for centering and (g) reflection of X-rays and arranged so as to be approximately overlapped. An angle calibration device using an X-ray polygonal mirror, comprising: a table; and (h) a wide-angle X-ray detector that captures the reflection of the X-ray polygonal mirror. 2. The dispersed X-ray beam is expanded by an X-ray collimator to obtain a beam size that can be irradiated by the entire X-ray polygon mirror, and the divergence angle is suppressed to less than a second, so that the X-ray polygon mirror The two orthogonal reflecting surfaces are installed so as to be substantially parallel to the two attitude adjustment tilt stages, and the center line of the X-ray polygon mirror is adjusted to be parallel to the axis of the rotary table by using the reflection of X-rays. Then, by disposing the xy stage so that its center line and the axis of the rotary index table are approximately overlapped with each other and rotating the X-ray polygon mirror that has been adjusted, Bragg reflection occurs one after another to detect wide-angle X-rays. An angle calibration method using an X-ray polygonal mirror, characterized in that the position of the Bragg angle is determined by the reflection intensity curve captured by the instrument. 3. An angle calibration method using an X-ray polygonal mirror according to claim 2, wherein correction of temperature difference and X of the X-ray polygonal mirror are performed.
An angle calibration method using an X-ray polygonal mirror, wherein refraction correction is performed on a line to obtain a large number of correct geometric angles.