JP3582166B2 - Soft X-ray tomography - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tomography (CT: computer tomography) method for nondestructively examining a spatial distribution of impurities, defects, density and the like in industrial materials.
[0002]
[Prior art]
Conventional tomographic methods using X-rays having wavelengths mainly in the range of 0.1 ° to 1 ° include methods using X-rays from an X-ray tube, and SR Science and Technology Information Vol. 4, No. 12 (1994) pp. Some use monochromatic X-rays obtained from synchrotron radiation as introduced in 11-17.
[0003]
[Problems to be solved by the invention]
Conventionally, as described above, as X-ray tomography, X-rays having a relatively short wavelength in the range of 0.1 to 1 mm are used, so that defects in light element materials such as plastic and rubber can be eliminated. I could not shoot with high contrast.
[0004]
In view of such problems in the prior art, the present invention provides an X-ray tomography method capable of non-destructively examining the spatial distribution of impurities, defects, and densities even in light element materials such as rubber and plastic. It is intended to be.
[0005]
[Means for Solving the Problems]
In soft X-ray tomography according to the present invention, beyond 1Å by using (111) plane of the silicon with respect to stored electrons energy emitted from the synchrotron radiation apparatus the following small 1GeV synchrotron radiation It is characterized in that it is monochromaticized into soft X-rays having a wavelength within a range of up to 10 °, and a tomographic image of an object is photographed using the softened X-rays .
[0008]
In the soft X-ray tomography according to the present invention, since tomography is performed using soft X-rays having a wavelength in the range of more than 1 ° to 10 °, impurities in light element materials such as plastics and rubbers, Spatial distribution such as defects and density can be detected non-destructively with high contrast.
[0009]
By using the (111) plane of silicon, soft X-rays having a desired wavelength can be extracted.
[0010]
Since synchrotron radiation is white X-rays including X-rays having various wavelengths, soft X-rays having a desired wavelength can be obtained by using the (111) plane of silicon.
[0011]
Since the radiation from a small synchrotron radiation device having a stored electron energy of 1 GeV or less does not include short-wavelength X-rays, it is necessary to obtain monochromatic soft X-rays using the (111) plane of silicon. In addition, it is possible to prevent higher-order diffracted X-rays having a wavelength that is a fraction of the wavelength of the monochromatic X-ray from being mixed.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a graph showing the influence of the wavelength of X-rays on the material transmittance of X-rays. In the graph of FIG. 1, the horizontal axis represents the density or atomic number of a substance, and the vertical axis represents the transmittance (%) per unit length of X-rays passing through the substance. Curve 1A represents a typical example of the transmittance of X-rays having a wavelength λ in the range of 0.1 ° to 1 °, and curve 1B represents the transmittance of X-rays having a wavelength λ in the range of 1 ° to 10 °. This shows a typical example.
[0014]
The X-ray tomographic image shows the distribution of the X-ray transmittance in the cross section of the transmitting object. That is, the difference in the X-ray transmittance is read as the density of the cross-sectional image.
[0015]
Now, as shown in FIG. 1, if there are two substances A and B made of the same element having slightly different densities, a hard X-ray having a wavelength in the range of 0.1 ° to 1 ° is used. If you were, since almost no difference in the X-ray transmittance per unit length as indicated at T _1, determination of substances a and B it is very difficult. However, the use of soft X-rays having a wavelength in the range of 1A～10A, the difference in X-ray transmittance increases between the two substances A and B as indicated by reference numeral T _2, they Can be easily identified.
[0016]
At this time, by using a soft X-ray monochromatized by utilizing a diffraction phenomenon using a silicon single crystal or the like, a contrast resolution based on a difference in density or atomic number can be increased.
[0017]
In addition, since the synchrotron radiation includes high-intensity white X-rays, a tomographic photograph can be taken in a short time by using monochromatic X-rays from the synchrotron radiation.
[0018]
Incidentally, the synchrotron radiation light has a radiation light spectrum distribution that differs depending on the stored electron energy in the synchrotron radiation device that emits the synchrotron radiation light.
[0019]
FIG. 2 is a graph showing the relationship between the stored electron energy of the synchrotron radiation device and the characteristics of X-rays contained in the synchrotron radiation. In the graph of FIG. 2, the horizontal axis represents the wavelength (Å) of X-rays contained in the synchrotron radiation, and the vertical axis represents the X-ray intensity (relative value) of each wavelength. Curve 2A represents radiation from a medium or large synchrotron radiation device having a stored electron energy exceeding 1 GeV, and curve 2B represents radiation from a small synchrotron radiation device having a stored electron energy of 1 GeV or less. Represents light. On the other hand, when a monochromatic white X-ray as shown in FIG. 2 is performed by a diffraction phenomenon using a crystal, an X-ray having a higher order wavelength such as 1/2, 1/3 of a desired monochromatic wavelength is used. Is necessarily included by higher-order reflection.
[0020]
For example, in the case of obtaining monochromatic X-rays having a wavelength of 4 ° in FIG. 2, X-rays having a wavelength such as Å or Å of 4 ° are included in the radiation from a small synchrotron radiation device. , Which can mainly extract only soft X-rays having a wavelength of 4 °, but may cause higher-order reflections in the radiation from medium- or large-sized synchrotron radiation devices. Since high-intensity short-wave X-rays are included, even after passing through a crystal for monochromatization, hard X-rays having a short wavelength within the range of 0.1 to 1 ° conventionally used are included. Cannot be avoided.
[0021]
Therefore, it is desirable to use a small synchrotron radiation device having a stored electron energy of 1 GeV or less for soft X-ray tomography.
[0022]
In addition, white X-rays from an X-ray tube can be monochromatic and used for soft X-ray tomography. In this case, the intensity of white X-rays from the X-ray tube is lower than the intensity of white X-rays from the synchrotron radiation device, but the X-ray generator is compact, so soft X-ray tomography can be simplified. Can be performed.
[0023]
FIG. 3 shows an embodiment of the soft X-ray tomography according to the present invention. In FIG. 3, synchrotron radiation light is emitted into a beam line 3 by the action of a bending electromagnet 2 provided on an electron orbit of a synchrotron 1. As the synchrotron 1, a superconducting small SR device NIJI-3 installed at the Harima Research Institute, Sumitomo Electric Industries, Ltd. can be used. White X-rays including X-rays of all wavelengths are introduced into the beam line 3 and are made monochromatic by the two-crystal spectroscope 4. The monochromatic soft X-ray is introduced into the sample rotating device 5. In the sample rotation device 5, a sample to be transmitted through X-rays and to be photographed tomographically is installed on a sample rotation mechanism. The X-ray transmitted through the sample in the sample rotating device 5 is guided into the soft X-ray imaging device 6, and a tomographic photograph is taken.
[0024]
Using a soft X-ray tomography system as shown in FIG. 3, a tomographic image of polyethylene was taken and reproduced by soft X-rays having a wavelength of 3 °, and spherical voids having a diameter of 10 μm were observed. We were able to. In the conventional hard X-ray tomography, only large holes having a diameter of about 200 μm can be observed under the same imaging conditions.
[0025]
【The invention's effect】
As described above, when the soft X-ray tomography according to the present invention is used, tomography is performed using soft X-rays having a relatively long wavelength in the range of more than 1 ° to 10 °, so that the contrast resolution is improved. improves. Therefore, by the soft X-ray tomography according to the present invention, it is possible to observe minute defects and non-uniformity in density in pores and fibers in light element materials such as polyethylene or ceramics and rubber products with high accuracy. Become.
[Brief description of the drawings]
FIG. 1 is a graph showing the influence of the wavelength of X-rays on the transmittance per unit length of X-rays penetrating materials having different densities or atomic numbers.
FIG. 2 is a graph showing the effect of a difference in stored electron energy of a synchrotron radiation device on the wavelength and intensity of X-rays contained in radiation.
FIG. 3 is a block diagram schematically showing a soft X-ray tomography system for performing a soft X-ray tomography method according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Synchrotron 2 Bending electromagnet 3 Beam line 4 2 Crystal spectroscope 5 Sample rotation device 6 Soft X-ray imaging device

Claims (1)

By using a silicon (111) plane for synchrotron radiation emitted from a small synchrotron radiation device having a stored electron energy of 1 GeV or less , a soft X having a wavelength in the range of more than 1 ° to 10 ° is used. A soft X-ray tomography method characterized by monochromaticizing a line and taking a tomographic image of an object using the monochromatic soft X-ray.

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