JP4483754B2 - X-ray focusing device - Google Patents

Description

  The present invention relates to an X-ray analyzer, an XRD, and an X-ray that perform analysis using X-rays, such as an electron probe microanalyzer (EPMA), a scanning electron microscope (SEM), a transmission electron microscope, and a fluorescent X-ray analyzer. The present invention relates to an X-ray focusing apparatus used for focusing or collimating X-rays in a CT, an X-ray apparatus or the like.

  The electron beam probe microanalyzer (EPMA) irradiates a sample with an electron beam with a small diameter having high energy as an excitation ray, and thereby the intrinsic electron emitted to the outside when the inner electrons of the components contained in the sample are excited. By analyzing X-rays (characteristic X-rays), elements are identified and quantified, and the distribution of elements is examined. In addition, the scanning electron microscope (SEM) generally detects secondary electrons and reflected electrons generated from the irradiation position of the electron beam, but recently, an X-ray analysis is performed by adding an energy dispersive X-ray detector. A device that enables this is also being developed.

  In order to collect and collimate X-rays in this type of X-ray analyzer, a kind of X-ray focusing device called a multi-capillary (sometimes called polycapillary) X-ray lens has been known. (See Patent Documents 1 and 2, etc.). FIG. 3 is a diagram showing an example of a form of a multicapillary X-ray lens, FIG. 4 is a schematic diagram showing an example of a use form of a point / parallel type multi-capillary X-ray lens, and FIG. 5 is an X-ray transmission in the multicapillary X-ray lens. FIG.

  A multicapillary X-ray lens has a basic structure in which a large number of capillaries (about several hundred to one million) made of borosilicate glass having a small diameter of, for example, an inner diameter of about 2 to over 10 μm are bundled. As shown in FIG. 5, using the principle that X-rays incident on the inside of one capillary 22 travel while totally reflecting the inner peripheral surface of the glass wall at an angle less than the critical angle, X-rays are guided efficiently. Even if the capillary 22 is linear as shown in FIG. 5 (a) or the capillary 22 is curved as shown in FIG. 5 (b), X-rays can be guided in the same manner.

  There are various types of multicapillary X-ray lenses. For example, the multicapillary X-ray lens 20 shown in FIG. 3A has a large solid angle on the incident side end face for X-rays emitted from an X-ray source that can be regarded as almost a point. Thus, it is a point / point type that focuses and collects X-rays emitted from the opposite emission side end face at one point. Similarly, the multicapillary X-ray lens 21 shown in FIG. 3B emits a parallel beam from the exit side end surface after taking in X-rays emitted from substantially one point on the entrance side end surface with a large solid angle. The reverse path is a point / parallel type. In addition, there is a parallel / parallel type in which both end surfaces receive and emit parallel beams.

  The point / parallel type multi-capillary X-ray lens 21 is used in an X-ray analyzer configured as shown in FIG. 4, for example. That is, the intrinsic X-rays emitted from the sample 5 by the irradiation of the excitation beam such as an electron beam are generated by the point / parallel multicapillary X-ray lens 21 arranged so that the point focal point comes near the irradiation region of the excitation beam. The light is efficiently collected and collimated, and is irradiated onto the flat plate-type spectral crystal 6. X-rays are reflected while being wavelength-dispersed by the spectral crystal 6, and the dispersed light is detected by the X-ray detector 7. In this configuration, when the spectral wavelength is scanned, the spectral crystal 6 is rotationally driven by an angle θ about an axis perpendicular to the paper surface, and the X-ray detector 7 also rotates the rotational angle of the spectral crystal 6 about the same axis. It is rotationally driven so as to maintain an angle 2θ that is twice as large as θ.

  However, strictly speaking, all of the X-rays emitted from the parallel end 21b of the multicapillary X-ray lens 21 are not parallel light, and part of the X-ray is diffusive light in principle. That is, as shown in FIG. 6, X-rays travel while totally reflecting the inner wall surface of one capillary 22, but the maximum reflection angle is the critical angle θ. Therefore, when X-rays are emitted from the end of the capillary 22, the X-rays may spread with an opening angle of the critical angle θ with respect to the optical axis (center line of the capillary 22) C. As a result, as shown in FIG. 7, some X-rays emitted from the end face on the parallel end 21b side of the point / parallel type multicapillary X-ray lens 21 travel as completely parallel light, but some of them are shown in the figure. Therefore, at a position away from the end face of the parallel end 21b by a distance t, for example, irradiation with a size larger than that of the irradiation region B1 with respect to ideal parallel light may occur. The X-ray hits the area B2.

  When the size of the irradiation region increases in this way, as shown in FIG. 4, some X-rays do not hit the spectral crystal 6, and the X-ray intensity toward the X-ray detector 7 decreases and the detection sensitivity and accuracy deteriorate. There is a risk. In particular, in the arrangement of the X-ray optical system in which the distance between the parallel end 21b of the multicapillary X-ray lens 21 and the spectral crystal 6 is long, such a problem becomes more serious.

Japanese Examined Patent Publication No. 7-11600 Japanese Patent Publication No. 7-40080

  The present invention has been made to solve the above-mentioned problems, and the main purpose of the present invention is that the size of the irradiation region of X-rays emitted from the end face on the side where the X-rays converted into parallel light are originally desired to be acquired is It is an object to provide an X-ray focusing apparatus that can suppress the size of the end face from becoming larger than that of the end face, and can make the size of the X-ray irradiation region substantially the same regardless of the distance from the end face.

The present invention was made in order to solve the above-the order to you collimating and focusing the X-rays emitted from one point or small area, capillary collection, each bundled tubules number for guiding the X-rays In an X-ray focusing device consisting of a body,
End on the side of I De parallel X-rays In the said capillary assembly, by an angle which a plurality of capillaries positioned in the outermost periphery in the radial direction corresponds to the total reflection critical angle for X-rays passing through the inner tubular The capillary tube is bent so as to be directed toward the center of the capillary tube assembly, and the capillary tube on the inner peripheral side of the tube assembly is also moved toward the center by a predetermined angle smaller than the angle corresponding to the total reflection critical angle depending on the position. By being bent so as to be oriented, the whole has a narrowed shape.

  In the conventional X-ray focusing apparatus of this type, the end portions of all the thin tubes constituting the thin tube assembly are arranged in parallel with each other on the “end surface on the side where parallel X-rays are incident or emitted”. On the other hand, in the X-ray focusing apparatus according to the present invention, in the “end surface on the side where parallel X-rays are incident or emitted”, the thin tubes are not arranged in parallel to each other but are positioned on the outermost periphery. The narrow tube is inclined or bent by the critical angle of total reflection so as to face the optical axis (substantially the center line of the thin tube) as a whole of the thin tube assembly. It is inclined or bent in the direction approaching the axis. That is, since the X-rays pass through each narrow tube and exit from the end face, the X-rays that may theoretically occur are emitted in the direction approaching the optical axis. The X-ray irradiation range is almost the same as the area of the end face, and the size of the irradiation area does not depend on the distance from the end face.

  Here, the “angle corresponding to the total reflection critical angle” includes not only an angle that completely coincides with the critical angle, but also an angle that roughly corresponds to the critical angle. This is because even if the angle is not completely coincident with the critical angle, if the angle is close to the critical angle, an effect almost equal to that in the case of coincidence is achieved.

As an exemplary embodiment, an X-ray focusing device according to the present invention, each capillary end in the end face on the side of I De parallel X-rays In the said capillary assembly, axially outward from the end surface What is necessary is just to set it as the structure formed so that it may have a point focus.

In this configuration, even one point or focused by collimating be that thin tube assemblies X-rays emitted from the minute area (multicapillary X-ray lens), structurally the point / point type rather than a point / parallel type It is. However, the total reflection critical angle of the X-ray (in FIG. 6 theta) from actually very small (typically 1 ° or less), the focal point of the outer end face that shines out of the parallel X-rays is very from the end face It will be located away.

  As described above, according to the X-ray focusing apparatus of the present invention, it is possible to suppress the expansion of the X-ray irradiation area outside the end face where parallel X-rays are desired to be acquired. X-rays can be introduced, thereby avoiding a decrease in the intensity of the X-rays and contributing to improvement in analysis sensitivity and accuracy.

  An embodiment of the X-ray focusing apparatus according to the present invention will be described below with reference to FIGS.

  FIG. 1 is a detailed configuration diagram of the main part, that is, both ends of the multicapillary X-ray lens according to the present embodiment. In the multicapillary X-ray lens 1 shown in FIG. 1, the left end 1a corresponds to the left end (focusing end) of the point / parallel multicapillary X-ray lens shown in FIG. 3B, and the right end 1b is This corresponds to the right end (parallel end) of the point / parallel multicapillary X-ray lens shown in FIG. The left end 1a is the same as the conventional one, and the end of each capillary is narrowed so that the center line of each capillary passes one point near the outside of the left end 1a.

  On the other hand, the right end portion 1b is different from the conventional one in that the capillaries are not bundled in parallel with each other, but the center line of the outermost capillary is the central axis A of the X-ray lens 1 by an angle corresponding to the critical angle θ. It is bent inward so that it points to The capillaries on the inner peripheral side of the outermost periphery are also bent inward so that the center line is directed to the central axis A by a predetermined angle smaller than the angle corresponding to the critical angle θ, depending on the position. ing.

  That is, the right end portion 1b has a narrowed shape as a whole when viewed in detail. However, since the critical angle θ is generally very small and is usually 1 ° or less (for example, about 0.1 °), the focal point formed by the right end portion 1b is located at a position far away from the end face of the right end portion 1b. Therefore, it is quite different from the conventional point / point type multi-capillary X-ray lens as shown in FIG.

  In the multicapillary X-ray lens 1 of the present embodiment having the above-described configuration, the X-rays that are to spread outward among the X-rays emitted from the capillary located at the outermost periphery of the right end 1b are just parallel to the central axis A. Will go on. Therefore, the irradiation range of X-rays emitted from the entire end face of the right end portion 1b is a range indicated by reference numeral 2 in FIG. 1, and is almost the same as the area of the end face. Therefore, the size of the X-ray irradiation range is kept the same regardless of the distance from the end face. Strictly speaking, for example, X-rays emitted from the end face of the outermost capillary and traveling toward the central axis A will eventually jump out across the central axis A, so that they are very far from the end face. The size of the irradiation range becomes large at a certain position. However, since the critical angle θ is small as described above, this is not a problem at all.

  By using the multicapillary X-ray lens 1 of the present embodiment for an X-ray analyzer, it is possible to irradiate the plate-type spectral crystal 6 without waste as shown in FIG. Therefore, the intensity of X-rays incident on the X-ray detector 7 is increased, and analysis with high sensitivity and high accuracy becomes possible.

  It should be noted that the above embodiment is an example of the present invention, and it is obvious that any modification, correction, or addition as appropriate within the scope of the present invention is included in the scope of the claims of the present application.

The block diagram of the principal part of the X-ray focusing apparatus which is one Example of this invention. The schematic block diagram of the X-ray inspection apparatus which is an application example of the X-ray focusing apparatus of a present Example. The figure which shows the example of a form of the conventionally known multicapillary X-ray lens. The schematic block diagram of the X-ray inspection apparatus using the conventional multicapillary X-ray lens. The principle figure of transmission of X-rays in a multicapillary X-ray lens. The figure for demonstrating the problem of the conventional multicapillary X-ray lens. The figure for demonstrating the problem of the conventional multicapillary X-ray lens.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multicapillary X-ray lens 1a ... Left end part 1b ... Right end part 5 ... Sample 6 ... Spectral crystal 7 ... X-ray detector

Claims (2)

In order to you collimating and focusing the X-rays emitted from one point or small area, in each X-ray focusing device comprising a capillary numerous bundled capillary assembly for guiding the X-rays,
End on the side of I De parallel X-rays In the said capillary assembly, by an angle which a plurality of capillaries positioned in the outermost periphery in the radial direction corresponds to the total reflection critical angle for X-rays passing through the inner tubular The capillary tube is bent so as to be directed toward the center of the capillary tube assembly, and the capillary tube on the inner peripheral side of the tube assembly is also moved toward the center by a predetermined angle smaller than the angle corresponding to the total reflection critical angle depending on the position. An X-ray focusing apparatus characterized by being bent so as to be oriented and having a narrowed shape as a whole. Each tubular end portion at the end face on the side of I De parallel X-rays In the said capillary assemblies claims, characterized in that it is formed so as to have a point focus on the outside in the axial direction from the end surface 2. The X-ray focusing apparatus according to 1.

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