JPH0711600B2 - X-ray concentrator - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an apparatus for focusing an X-ray beam on a microscopic area.

(Prior Art) A sample surface is irradiated with a sample using X-rays as excitation rays and a secondary radiation emitted from the sample is detected by an analysis method such as X-ray photoelectron spectroscopy or fluorescent X-ray analysis. When analyzing a very small area (for example, a diameter of 100 μm to 1 mm), there is no simple means for concentrating X-rays, so a method such as a diaphragm or mask is usually used to limit the X-ray irradiation area on the sample surface. Although used, it is difficult to obtain sufficient irradiation intensity because X-rays cannot be converged by this method.

As a means for converging X-rays, in principle, diffraction by a crystal lattice is used, X-ray total reflection that occurs on the material surface when X-rays are incident on the material surface at a low incident angle, or Can utilize diffraction by a Fresnel zone plate, and several proposals have been made.

(Problem to be Solved by the Invention) The above-described method of utilizing X-ray diffraction by a crystal plane has the same configuration as an X-ray spectrometer using a curved crystal, but it is difficult to bend the crystal into a spherical surface, Since the solid angle formed by the crystal plane with respect to the X-ray source cannot be made very large, the utilization efficiency of X-rays is not sufficient. In the method using total reflection, it is necessary to make X-rays incident on the reflecting surface smoothly, so
It is difficult to increase the solid angle formed with respect to the radiation source, the X-ray utilization efficiency is not sufficient, and if the utilization efficiency is to be increased, the reflecting surface becomes very large. The method using the Fresnel zone plate theoretically has an excellent X-ray focusing ability, but there is a technical limit to the diameter of the zone plate that can be produced, the brightness is not sufficient, and the utilization efficiency of the X-ray source is low. Low.

As described above, whichever focusing method is used, the X-rays are well converged, and focused irradiation of minute points is possible, but only a part of the X-rays emitted from the X-ray source is incident on the focusing means. The use efficiency of X-rays is low as much as possible, and it is difficult to obtain a sufficient irradiation X-ray intensity.

In view of such a point, the present invention seeks to obtain a simple and comparatively small means capable of efficiently concentrating X-rays in a minute area.

(Means for Solving the Problem) The extension of the center line of each pipe from one pipe end to the outside intersects at one point, and the extension of the center line at the other end of each pipe to the outside of the pipe end is the above. A large number of tubes are interconnected so that they will meet at a point different from one point, the X-ray source is located at the meeting point of the tube center line extension on one end side of this tube group, and each tube center at the other end side The irradiated point of the sample was positioned at the meeting point of the line extension.

(Operation) In the above-described embodiment, one end of each tube is directed toward the X-ray source, and the solid angle formed by the tube end opening of one tube with respect to the X-ray source is small. The X-rays are incident at a grazing incidence angle, and total internal reflection is performed on the inner surface of the tube.
Therefore, even if the tube is bent, the X-rays can be emitted from the other end by repeating total reflection. Since the total reflection angle of X-rays is small, unlike the optical fiber in visible light, the divergence angle of the X-rays emitted from the tube end is small and it is close to a parallel ray bundle.
Since the extension of the center line of each tube is associated with one point even at the X-ray emission end, all the centers of the X-ray flux emitted from each tube pass through the above-mentioned association point, and Since the spread angle of the emitted X-ray flux is small, X-rays are concentrated. Even if the tube end opening of one tube has a small solid angle with respect to the X-ray source, the total solid angle with respect to the X-ray source can be easily increased by bundling multiple tubes. ,
The efficiency of X-ray concentration is significantly improved as compared with the conventional case.

(Embodiment) FIG. 1 shows an embodiment of the present invention. In the figure, reference numeral 1 is a quartz glass (SiO ₂ ) tube having an inner diameter of 10 μm. The tubes are assembled so that one end side is perpendicular to one spherical surface S1 and the other end side is perpendicular to another spherical surface S2.
An electron irradiation point on the target T of the X-ray tube X is located at O1, and X-rays are concentrated in a minute range around the center O2 of the other spherical surface S2. Each tube 1 is connected and fixed to each other at both ends, but is free in the middle, has a considerable flexibility, and there is some degree of freedom in the mutual positional relationship between the spherical surfaces S1 and S2.

The ends of tube 1 do not have to be spherically aligned. In the embodiment shown in FIG. 2, the ends of the tube 1 are aligned in a plane. Even in this case, the tubes are conically assembled at the tube ends so that the extensions of the tube center lines of the tubes intersect at one point. It suffices that the ends of the respective tubes have their center lines meeting at one point, and they may be formed in any shape within a range in which a part of the tubes does not project to the surroundings so as to be shaded by incident X-rays.

The X-ray utilization efficiency in this configuration is determined by the sum of the solid angles of the tube lumen end faces of the end faces of the tube group facing the X-ray source. Even with the same efficiency, the thinner the wall thickness of the tube, the smaller the outer diameter of the tube assembly can be.
The quartz tube is formed by melt drawing of a thick tube, and in that case the cross-sectional shape shrinks in a similar shape, so the inner diameter is 10 μm and the outer diameter is 12 μm.
A quartz tube of about m can be easily obtained. To bind such a capillary tube as shown in FIG. 1 or FIG. 2, the following is done. In FIG. 3, F is a flexible sheet of plastic, on the surface of which a thermoplastic adhesive such as a vinyl adhesive is applied and placed on a flat plate C, and a bundle of tubes 1 is placed on it. Is made vertical and the lower end thereof is brought into contact with the sheet F, and the tube end is aligned on a flat surface on the sheet F and bonded to the sheet F. When the adhesive is dried, the sheet F is placed on the spherical shell B having many holes as shown in FIG. 4, and when the inside of the spherical shell B is evacuated, the sheet F is adsorbed on the spherical shell surface and spherical. Turn to. Since each tube 1 is bonded vertically to the sheet surface, the center line of the tube end faces the center of the spherical shell B. In this state, a casting resin P such as polyester is injected between the tubes 1 and cured. After the resin P is hardened, it is heated to soften the adhesive between the sheet F and the tube 1 and peel the sheet F from the bundle of tubes 1.
After that, the end surface of the tube 1 is polished into an appropriate shape, and the polished surface is suction-cleaned by a vacuum device. The other end of the tube bundle is similarly bundled and solidified into a certain shape.

The critical angle φ when the X-rays are totally reflected is given by the following equation.

δ = 2.02 (m / z) ρλ ² × 10 ⁶ where z is atomic number, m is atomic weight, ρ is density, and λ is X-ray wavelength. Therefore, the material of the tube to be used must be properly selected according to the wavelength range of X-rays and the required tube inner diameter.
When the material is quartz glass and X-rays are Al Kα rays of 8,339Å, the critical angle φ is about 1,1 °. Inner diameter of tube 1 is 10 μm
At this time, the radius of the spherical surface S1 in FIG. 1 is about 0.6 mm so that the angle of incidence on the inner surface of the tube is about 1,1 °. Actual S
Since the radius of 1 is about several cm, the incident angle of X-rays on the inner surface of the tube 1 is about 1/100 of 1,1 °. Since the spread angle of the X-ray emitted from the tube 1 is about twice the angle of incidence on the inner surface of the tube,
If the divergence angle is also extremely small and is equal to the radius of the radius S1 of the spherical surface S2 in FIG. 1, the X-ray concentration range is about the inner diameter of the tube 1,
That is, it becomes about 10 μm.

(Effects of the Invention) According to the present invention, the solid angle formed by the X-ray incidence side of the X-ray concentrating means with respect to the X-ray source can be easily increased, and the X-ray incidence end face is of the conventional total reflection type. Unlike the concave crystal type, it is perpendicular to the incident X-rays, so the device can be made compact and the utilization efficiency of X-rays is high, despite the large solid angle toward the X-ray source. Since X-rays can be intensively applied to the micro area of the sample, the sensitivity of the micro area analysis of the sample can be easily improved. Also, since the device has some flexibility, X
There is an advantage that the positional relationship between the radiation source and the X-ray irradiation point of the sample can be freely adjusted to some extent.

[Brief description of drawings]

FIG. 1 is a side view of an embodiment of the present invention, FIG. 2 is a side view of another embodiment, and FIG. 3 is a side view showing a first stage of the procedure for binding the pipes 1 in the above embodiment. Similarly, FIG. 4 is a side view showing the second stage. 1 ... Tube, T ... X-ray tube target, O2 ... X-ray concentration point, F ... Flexible sheet, C ... Flat plate, B ... Spherical shell.

Claims (1)

[Claims] 1. A flexible tube has a center line extending outward from one end of the tube at one point, and a center line extending from the other end of the center line of each tube extending outward. A large number of tubes are mutually connected so as to be associated with another point different from the above-mentioned one point, an X-ray source is located at the extension meeting point of each tube center line on one end side of this tube group, and an X-ray is emitted from the other end side. X-ray concentrator designed to emit light.