JPH0527840B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an X-ray divergence angle limiter. More specifically, in X-ray generators, various scientific measurement instruments using X-rays, and medical and industrial X-ray irradiation/inspection equipment, a single or multiple X-ray generator is installed to obtain an X-ray flux that is parallel or below a specific divergence angle. The present invention relates to an X-ray divergence angle limiter using small holes or slits (hereinafter abbreviated as slits).

Prior Art Conventional X-ray generators collide electrons accelerated at a predetermined voltage in a vacuum with a metal anticathode (or anode), and emit the resulting bremsstrahlung radiation or characteristic X-rays into the atmosphere through a beryllium window. It has become a method to take it out.

Here, X-rays are emitted in all directions from the position where individual electrons lose their kinetic energy after collision. Therefore, as long as the part where the electrons collide has a finite area on the anticathode, a point in space away from the X-ray generation position can be reached in a direction within the range from which the finite area where the X-rays are generated is expected. X-rays will be incident from there. Therefore, for various types of equipment that require parallel or nearly parallel X-ray flux,
There is no choice but to use an X-ray generating device with a limited upper limit of the ray generating area. In addition, in order to limit the divergence angle of X-rays, either one or both of the X-ray generator and the It is necessary to use an X-ray divergence angle limiter to extract only the rays.

Therefore, it is not possible to simultaneously irradiate a large area of the sample with parallel or nearly parallel X-rays, and if the distance between the X-ray generator and the sample is increased in order to improve parallelism, the distance will increase. There was a problem that the X-ray intensity attenuated in inverse proportion to the square.

Purpose of the Invention The present invention aims to solve the above-mentioned conventional problems, and its purpose is to use parallel or nearly parallel X-rays (collectively referred to simply as parallel X-rays) to
It prevents X-ray intensity and attenuation due to the distance between the X-ray source and the sample, makes it possible to irradiate a wide sample area with X-rays, and at the same time, when the sample area is extremely small, it is possible to reduce the The object of the present invention is to provide an X-ray divergence angle limiter that can obtain an X-ray intensity several tens of times higher than that of a conventional one by modifying the X-ray divergence angle limiter.

Structure of the Invention As a result of intensive research to achieve the above object, the present inventors found that the inner cross section is circular, elliptical, or polygonal, and the inner wall surface is a smooth surface capable of total X-ray reflection. It has been found that the above object can be achieved by using an X-ray divergence angle limiter consisting of one or more thin hollow tubes bundled in parallel. The present invention was completed based on this knowledge.

The gist of the present invention is to use one or two thin hollow tubes each having a circular, elliptical or polygonal inner cross section and a smooth inner wall surface capable of causing total X-ray reflection.
There is an X-ray divergence angle limiter made of books or more bundled in parallel.

To explain the X-ray divergence angle limiter of the present invention based on the drawings, FIGS. 1 and 2 are cross-sectional views of an embodiment of the X-ray divergence angle limiter (hereinafter simply abbreviated as limiter) of the present invention. be. Figure 1 shows the case of a multi-tube bundle, and Figure 2 shows the case of a single tube. The broken line shown in Figure 1 is the conventional
This figure shows the window in the radiation generating device from which X-rays are taken out. 13 is the wall of the device, 12 is the beryllium window, and the left side of this window is the vacuum. Reference numeral 11 indicates an X-ray generating section on the anticathode. Although there are various forms of conventional X-ray generators, the X-ray extraction section is generally as shown in this drawing, and the restrictor of the present invention can be connected to any form of the X-ray generator side. It is possible.

1 is a cover for shielding divergent X-rays when the restrictor of the present invention is joined to an X-ray generator, 2 is an outer cylinder, 3 is a hollow tube, and 4 is a fixing for attaching the controller to the X-ray generator. 5 is an X-ray entrance port, 6 is an X-ray exit port, 7 is a screw, and 8 is a screw receiver. The X-rays generated in the X-ray generator 11 enter through the entrance port 5 and exit through the exit port 6 while undergoing total reflection within the hollow tube 3 . The hollow tube 3 has an inner cross section of a circle, an ellipse, or a polygon, and its inner wall surface is smooth enough to allow total reflection of X-rays. The thinner the wall thickness is, the more efficiently the generated X-rays can be utilized.

The inner diameter φ _i of the hollow tube 3 is determined by the distance l ₁ from the X-ray generator 11 to the entrance port 5 and the critical angle of total reflection of the X-rays used.
The following conditions are satisfied between Q and _c . (See Figure 3) φ _i ≦2Q _c・l _1However , Q _c is in radian, and φ _i and l ₁ are in mm. The inner diameter φ _x of the outer cylinder 2 is equal to or larger than the practical X-ray generation area. The X-ray generation region refers to the region on the anticathode where electrons collide, but in conventional X-ray generation devices, the region is viewed at a low angle (6 to 10 degrees to the anticathode surface). Since there are cases where X-rays are extracted, in that case, it means an X-ray generation area viewed from the direction from which X-rays are extracted.

Next, the action of this restrictor will be explained with reference to FIG.

Figure 3-a is a schematic diagram of the conventional method in which a narrow limiter is provided in front of the sample in order to limit the divergence angle of the X-rays incident on the sample, and Figure 3-b is a schematic diagram of the restrictor of the present invention. FIG. 3 is a schematic diagram showing the divergence angle of X-rays when used. Note that the drawings will be explained assuming that the hollow tube is circular.

In the figure, φ _x is the X-ray generation area, l ₁ is the distance from the X-ray generation position to the entrance port of the restrictor, and l ₂ is the length of the restrictor, which connects the restrictor to the beryllium window for X-ray extraction. In the normal case of installation, it is also the distance from the window to the sample. φ _i represents the inner diameter of the hollow tube, which satisfies the relationship with the critical angle of total reflection of X-rays described above.

In Figure 3-a, ∠A=2φ _x /(l ₁ +l ₂ )
In Fig. 3-b, ∠B=2φ _i /l ₁
From the condition of hollow tube diameter φ _i , this is ≦2Q _c , which depends on the wavelength of the X-ray and the density of the material used for the tube. In the case of ordinary glass or metal tubes,
For X-rays with a wavelength of about 1.5 Å, 7 to 3 × 10 ^-3
It is about radian.

As is clear from the comparison between Fig. 3-a and Fig. 3-b, the method of Fig. 3-a using the thin wire can be used in Fig. 3-b.
In order to obtain the same parallel X-ray flux as in Figure 3--, the sample must be moved extremely far away from the X-ray source, or the area of the X-ray generation region and the irradiation area of the sample must be
It has to be made as small as φ _i of b. This is why the X-ray generation area of conventional X-ray generators is generally several tens of mm ² or less.

In the case of FIG. 3-b using the restrictor of the present invention,
The smaller the diameter of the hollow tube, the more parallel the X-ray flux is obtained, and the X-ray intensity at the entrance is not attenuated up to an arbitrary distance _l2 due to total reflection of the X-rays by the inner wall of the hollow tube. can lead to. l ₂ is 800mm
In this example, even if a normal glass tube is used,
The X-ray intensity ratio at the entrance and exit ports is 2:1,
This is about 40 times the conventional ratio of about 80:1 using thin film.

For example, in the X-ray lithography method, which uses X-rays to image a fine mask pattern on a crystal sample with a diameter of several centimeters or tens of centimeters, parallel beams with a wide cross-sectional area are required. The purpose of the restrictor of the present invention can be easily achieved by attaching or incorporating an X-ray generating device having an X-ray generating area as wide as or larger than that of the sample.

On the other hand, when the sample or analysis area is extremely small in various scientific experimental equipment that uses X-rays, for example, in an X-ray diffractometer, if the sample diameter is 0.03 mm or less, the intensity of the diffracted X-rays is extremely weak. , measurement is not easy with an X-ray diffractometer using a conventional X-ray generator and X-ray divergence angle limiter. This is equivalent to the case where the narrowness is set to 0.03 mm or less in Fig. 3-a. In such cases, among the conventional X-ray generators, especially the microfocus type
If you use an X-ray generator with a particularly small (≦0.1φ) X-ray generating area called a ray generator, and use it with a restrictor as shown in Figure 2 of the present invention, the X-ray generator and the sample will be separated. There is no distance limit, and since the X-ray source is a fine focus X-ray source, X-rays with higher brightness can be used. Therefore, it becomes possible to analyze minute samples or minute regions, which was previously impossible.

Effects of the Invention When the restrictor of the present invention is used, as described above,
Since it is possible to prevent a decrease in intensity that is inversely proportional to the square of the distance from the ray generating part, it is not necessary to extract X-rays at a low angle with respect to the anticathode surface. Therefore, the area of the sample that is irradiated with parallel or nearly parallel X-rays becomes larger. For example, for applications such as lithography,
By using an X-ray generator that has a wide X-ray generation area equal to the sample surface and extracting X-rays by attaching the restrictor of the present invention at an arbitrary angle to the anticathode surface, it can simultaneously generate parallel X-rays over a wide area. or nearly parallel X
A beam of radiation can be irradiated.

In addition, in the opposite case to the above, that is, parallel or nearly parallel X-ray fluxes can be
The restrictor of the present invention is extremely effective even when irradiating the target area (mm or less). In that case, _the inner diameter φ _i of the hollow tube and the _diameter of the X-ray _generation region _φ If a reduced number of X-rays are used, the sample can be irradiated with high-intensity X-rays very easily.

We believe that the above-mentioned excellent effects can be achieved and that the present invention will contribute to various science, medical, and industrial X-ray equipment.

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of an embodiment of the X-ray divergence angle limiter of the present invention, in which FIG. 1 shows a multi-tube bundle, a second
The figure shows the case of a single tube. Fig. 3 is a schematic diagram showing the divergence angle of X-rays, Fig. 3-a shows the case when a narrow limit is provided in front of the sample in the conventional method, and Fig. 3-b shows the case in the restrictor of the present invention. . 1... Sheath that shields divergent X-rays, 2... Outer cylinder,
3...Hollow thin tube, 4...Jig, 5...X-ray entrance port, 6...X-ray exit port, 7...screw, 8...screw holder, 11...X-ray generation section, 12... Beryllium window, 13...wall.

Claims (1)

[Claims] 1 An X-ray divergence angle limiter consisting of one or more bundles of thin hollow tubules whose inner cross section is circular, elliptical, or polygonal, and whose inner wall surfaces are smooth enough to cause total X-ray reflection. vessel.