JP5338483B2 - X-ray focusing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To irradiate a micro-region on a sample with intense X-rays by improving focus blur at a focusing end of an MCX. <P>SOLUTION: In the MCX2, an X-ray incident edge 2a forms a parallel edge, an X-ray emitting edge 2c forms a parallel edge with the face area smaller than that of the X-ray incident edge 2a, and a bottleneck shape 2b on the way. Thereby, X-rays directed to the X-ray incident edge 2a from an X-ray source with a larger size exit from the X-ray emitting edge 2c as a parallel flux with a higher energy density and are directed to FZP3 arranged to share the same center axis. X rays from the X-ray source are effectively collected by the MCX2 to somewhat reduce the diameter and directed to FZP3 of a smaller diameter, and the convergence diameter of the X- rays is further reduced by the FZP3. Thereby, the X-rays is focused on an extremely narrow region. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an X-ray focusing apparatus used for focusing X-rays in an apparatus using X-rays such as an X-ray fluorescence analyzer, XRD, X-ray CT, and X-ray apparatus.

  In a micro fluorescent X-ray analyzer used for analyzing components in a micro area on a sample, it is necessary to irradiate the sample with X-rays emitted from an X-ray source with a very small diameter. In the micro fluorescent X-ray analyzer described in Non-Patent Document 1, for the above purpose, a multicapillary (referred to as “polycapillary” in this document, X-ray lenses are used (using the term “capillary”).

  A multi-capillary X-ray lens (hereinafter abbreviated as “MCX”) will be briefly described (see Patent Documents 1 and 2, etc.). FIG. 5 is a diagram showing a form example of MCX, and FIG. 6 is a principle diagram of X-ray transmission in MCX. The MCX has a basic structure in which a large number of tubules (capillaries) made of, for example, borosilicate glass having an inner diameter of about 2 to several tens of μm are bundled. As shown in the figure, the X-rays that enter the inside of one capillary 32 travel on the inner peripheral surface of the glass wall while being totally reflected at an angle less than the critical angle. Is an efficient guide. Even if the capillary 32 is linear as shown in FIG. 6 (a) or the capillary 32 is curved as shown in FIG. 6 (b), X-rays can be guided in the same manner.

  There are various forms of MCX, and the one shown in FIG. 5 (a) captures X-rays emitted from an X-ray source that can be regarded as almost a point with a large solid angle at the incident side end face, and the opposite emission side. This is a point / point type MCX 30 that focuses X-rays emitted from the end face to one point. In the same way as shown in FIG. 5 (b), a parallel beam is emitted from the exit-side end face after taking in X-rays emitted from substantially one point on the entrance-side end face with a large solid angle, or vice versa. This is a point / parallel type MCX31.

  As described above, although MCX can collect and guide X-rays with high efficiency, sufficient performance cannot always be obtained in terms of reducing the area to which the collected X-rays are irradiated. This is because, when X-rays are emitted from the end face of one capillary 32, the X-rays spread with a maximum opening angle of the total reflection critical angle. In addition, due to the manufacturing limitations of MCX, it is actually impossible to completely converge all the optical axes of a huge number of capillaries to one point. Thus, due to both theoretical factors and factors due to manufacturing limitations, the minimum focal spot size in the conventional MCX is limited to about 20 to 30 μm at most, and it is difficult to make the focal spot size smaller than this. .

  In order to solve these problems, the applicant of the present application has proposed a new X-ray focusing apparatus using a combination of MCX and a Fresnel zone plate (hereinafter abbreviated as “FZP”) having excellent aperture characteristics in Patent Document 3. FZP is a lens that uses Newton's ring diffraction and interference, and the aperture diameter can be made very small by increasing the processing accuracy, but it is difficult to make the size itself large, and light (X-rays) is captured. It has the characteristic that the solid angle is small. On the other hand, with MCX, it is easy to focus X-rays to an FZP outer diameter size (for example, about 1 mm) or less even if it is difficult to focus X-rays to a very small diameter. For these reasons, it can be said that the combination of MCX and FZP is an excellent combination that makes use of the advantages of both and conversely compensates for the defects.

Japanese Examined Patent Publication No. 7-11600 Japanese Patent Publication No. 7-40080 JP 2007-93316 A

"Energy dispersive micro fluorescent X-ray analyzer μEDX series", [online], Shimadzu Corporation, [Search April 26, 2009], Internet <URL: http://www.shimadzu.co.jp /surface/products/m_edx/index.html>

  However, in FZP that is actually easy to obtain, as shown in FIG. 7A, although X-rays incident parallel to the central axis are efficiently focused on the focal point F, When the light is incident at an angle of a certain degree or more, the light collection efficiency is considerably low. Therefore, no matter how efficiently the X-rays are guided by MCX, the intensity of the X-rays irradiated to the desired focal point F becomes low.

  It is effective to make the FZP thinner in order to increase the allowable incident angle of incident X-rays. However, when the FZP is made thin, X-rays having large energy are transmitted as they are without causing interference in the zonal pattern, so that X-rays are not collected at the focal point F, and a large-sized X-ray spot is formed. (See FIG. 7B). Of course, the use of FZP makes the X-ray intensity at the focal point F larger than the surrounding area. Therefore, the above configuration is useful for applications where there is no problem even if the X-ray is irradiated around the focal point F. However, in applications such as a micro fluorescent X-ray analyzer, it is necessary to prevent the X-ray from hitting the outside of the target micro area, and it is necessary to shield unnecessary X-rays with an aperture or the like. The efficiency of wire use is also poor.

  The present invention has been made to solve the above-described problems, and aims to achieve a high light collection efficiency while reducing the X-ray focal spot size in an X-ray focusing apparatus using MCX and FZP. It is said.

An X-ray focusing apparatus according to the first invention made to solve the above problems is
a) a plurality of bundled X-ray guiding thin tubes having a parallel portion in which each thin tube is arranged in parallel at least at a part between the X-ray incident side end portion and the X-ray emission side end portion; The X-ray emission side end portion is a parallel end in which the thin tubes are arranged in parallel and the area of the end surface is smaller than the cross-sectional area of the parallel portion, and the parallel portion and the X-ray emission side end portion a capillary assembly inner diameter of the capillary is formed so as to reduce gradually between,
b) A Fresnel zone plate disposed outside the X-ray emission side end of the capillary assembly so that the central axis of the capillary assembly coincides with the central axis;
It is characterized by having.

An X-ray focusing apparatus according to the second invention, which has been made to solve the above problems,
a) It is composed of a large number of bundled X-ray guiding thin tubes, and the X-ray emission side end portion is a tube tube assembly that is a focusing end having a focal point at a minute region that can be regarded as one point or a point outside thereof. And an ultra-long focal tube assembly having an angle of 1 ° or less between the axis of the tube located on the outermost periphery at the focusing end and the center axis of the tube assembly;
b) a Fresnel zone plate disposed outside the X-ray emission side end of the capillary tube assembly so that the central axis of the capillary tube assembly coincides with the central axis;
It is characterized by having.

  In the capillary tube assembly (multi-capillary X-ray lens), as described above, the X-ray proceeds on the inner wall surface of one capillary tube (capillary) by repeating total reflection. As long as the angle at which X-rays hit the inner wall of the thin tube is equal to or less than the total reflection critical angle, the thin tube may be bent or the inner diameter thereof may be gradually reduced.

  Therefore, in the X-ray focusing apparatus according to the first aspect of the invention, at least in the middle there is a parallel part and one end is a parallel end, and the area of the end face of the parallel end is smaller than the cross-sectional area of the parallel part, A narrow tube assembly in which the inner diameter of each thin tube at the parallel end is smaller than the inner diameter of each thin tube at the parallel portion is used, and the parallel end having a small cross-sectional area is defined as an X-ray emission end portion. The other end of this capillary tube assembly, that is, the X-ray incident end may be either a focusing end or a parallel end. In particular, when the size of the X-ray source is somewhat large, the X-ray incident side end portion is set as the parallel end where the parallel portion is extended so that X-rays emitted from the X-ray source can be received efficiently. Can do.

  For example, when X-rays emitted from an X-ray source having a certain size are introduced into each capillary tube from an X-ray incident end that is a parallel end, the X-rays are efficiently (with little loss) in each capillary tube. The light is guided and emitted as a substantially parallel X-ray bundle from the end face of the X-ray emission end which is a parallel end. Since the end face area of the X-ray exit end is smaller than the end face area of the X-ray entrance end, the X-ray flux density emitted from the X-ray exit end is greater than the X-ray flux density incident on the X-ray entrance end. Also grows. Since the X-ray flux that is almost parallel and has high luminous flux is incident on the Fresnel zone plate arranged outside the X-ray emission end, X-rays can be efficiently focused on the focal point that depends on the structure of the Fresnel zone plate with little loss. Are focused.

  On the other hand, in the X-ray focusing apparatus according to the second aspect of the invention, a capillary tube assembly whose X-ray emission end is the focusing end is used, but the focal point of the focusing end is at a position very far from the end face. Therefore, the X-rays incident on the Fresnel zone plate disposed outside the X-ray emission end can be regarded as a substantially parallel bundle, and the focal point depends on the structure of the Fresnel zone plate with a small loss, as in the first invention. X-rays are efficiently focused.

  Therefore, according to the X-ray focusing apparatus according to the first and second inventions, for example, X-ray intensity emitted from an X-ray source is efficiently collected to increase the X-ray intensity and concentrated in a very small area. Can be irradiated. Thereby, for example, even if the same X-ray source is used, the X-ray intensity per unit area in the X-ray irradiation region can be considerably increased as compared with the conventional case, and the interaction between the substance existing in the minute region and X-rays can be achieved. Information by (transmission, reflection, absorption, etc.) can be detected with high sensitivity and accuracy.

  Further, since the X-rays incident on the Fresnel zone plate are substantially parallel bundles, the Fresnel zone plate can be made somewhat thick. Therefore, even if the energy of the X-ray is high, it can be prevented from being transmitted through the Fresnel zone plate as it is, and it can be avoided that the X-ray hits outside a desired minute region. Thereby, for example, by using this X-ray focusing apparatus for a micro fluorescent X-ray analyzer, generation of undesired fluorescent X-rays and secondary electrons in parts other than the micro area can be prevented, and the component distribution Improvement of the spatial resolution can be achieved.

The block diagram of the principal part of the X-ray focusing apparatus which is 1st Example of this invention. The schematic block diagram of the X-ray inspection apparatus using the X-ray focusing apparatus of 1st Example. The block diagram of the principal part of the X-ray focusing apparatus which is 2nd Example of this invention. The figure for demonstrating the effect of the X-ray focusing apparatus of 1st and 2nd Example. The figure which shows the example of a form of a general 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 X-ray focusing apparatus.

[First embodiment]
An embodiment (first embodiment) of an X-ray focusing apparatus according to the present invention will be described with reference to FIGS. 1, 2, and 4. FIG.

  FIG. 1 is a configuration diagram of a main part of an X-ray focusing apparatus of the first embodiment, FIG. 2 is a schematic configuration diagram of an X-ray inspection apparatus using the X-ray focusing apparatus of the first embodiment, and FIG. 4 is a first embodiment. It is a figure for demonstrating the effect of the X-ray focusing apparatus of (and 2nd Example mentioned later).

  As shown in FIG. 1, the X-ray focusing apparatus 1 according to the first embodiment includes a parallel / parallel type MCX (capillary tube assembly in the present invention) 2 having both ends 2a and 2c being parallel ends, and an FZP3. Including. The diameter of the end face of MCX2 on the X-ray incident side (first parallel end) 2a is φ1, and the diameter of the end face of the X-ray emission side end (second parallel end) 2c is φ2 smaller than φ1, The bottle neck shape portion 2b has an outer diameter that continuously decreases from the X-ray incident side end portion 2a toward the X-ray emission side end portion 2c. In the bottleneck shape portion 2b, the inner diameter of each capillary is gradually reduced, and the capillary located on the outer peripheral side is gradually bent toward the central axis of the MCX2.

  The outer diameter of FZP3 (strictly speaking, the effective outer diameter capable of focusing X-rays) is larger than the outer diameter of the X-ray emission side end portion 2c of MCX2 (strictly speaking, the outer diameter of the capillary located at the outermost periphery) The FZP 3 is arranged so that the central axis coincides with the central axis of the X-ray emission side end 2c of the MCX 2 (which can be considered as the optical axis of the capillary located at the central part of a bundle of many capillaries).

  As shown in FIG. 2, in the X-ray inspection apparatus using the X-ray focusing apparatus 1 of the first embodiment, between the X-ray source 12 having a large size and the inspection object 11 placed on the sample stage 10. The X-ray focusing apparatus 1 is installed, and the primary X-rays emitted from the X-ray source 12 are efficiently irradiated to the inspection object 11 with a very small diameter by the X-ray focusing apparatus 1. In response to this, secondary X-rays (fluorescence X-rays) emitted from the inspection object 11 are detected by the X-ray detector 13, and information on the X-ray irradiation site on the inspection object 11 according to the detection signal ( For example, an image) is obtained. Of course, an MCX or the like may be provided on the detection side.

  X-rays emitted from the X-ray source 12 are efficiently taken into the capillaries from the X-ray incident side end 2a of MCX2, and are guided to the X-ray emission side end 2c while totally reflecting the inside of each capillary. During this time, the inside diameter of each capillary gradually decreases along the way, and many capillaries gradually bend, but the MCX2 structure is determined so that the angle at which the X-ray hits the inner wall of the capillary is less than the total reflection critical angle. By doing so, the X-ray can be guided to the X-ray emission side end portion 2c with almost no loss. When there is almost no loss, the X-rays introduced into the capillaries at the X-ray incident side end 2a depend on the ratio between the cross-sectional area of the X-ray incident side end 2a and the cross-sectional area of the X-ray emission side end 2c. Increase the density. That is, if the former area is A1 and the latter area is A2, the X-ray beam density emitted from the X-ray emission side end 2c is A1 / A2 times the beam density at the time of incidence.

  Then, almost all of the X-rays emitted from the capillaries at the X-ray emission side end 2c are incident on the small-diameter FZP 3 as a substantially parallel X-ray bundle. As described above, the X-rays incident on the FZP 3 at a high luminous flux density substantially in parallel are diffracted by the FZP 3 and are efficiently focused on the focal point F.

  The above operations and effects can be easily understood with reference to FIG. FIG. 4 is a schematic graph in which the horizontal axis indicates the lateral spread of irradiated X-rays and the vertical axis indicates the X-ray intensity. That is, when the light is emitted from a general MCX focusing end as shown in FIG. 5B, it becomes as shown by A in FIG. Is relatively large (at least about 20-30 μm). On the other hand, in the configuration of the first embodiment, the X-rays collected efficiently can be irradiated while being narrowed down, and therefore, as shown in B in FIG. That is, the irradiation X-rays can be reduced to a smaller size than before, and the total irradiation X-ray energy can be increased, so that both high spatial resolution and high sensitivity can be achieved.

  In the above embodiment, the X-ray incident end of the MCX is a parallel end, but this is useful when the X-ray source has a certain size or more. When the X-ray source has a size that can be regarded as one point, and X-rays are emitted radially from the X-ray source, MCX, which is a converging end having a point focus at the X-ray incident end, is used. May be. That is, the MCX used here is a parallel / parallel type or a point / parallel type, and has a shape in which the outer diameter is continuously reduced to a bottleneck shape in the middle of both ends.

[Second Embodiment]
Another embodiment (second embodiment) of the X-ray focusing apparatus according to the present invention will be described with reference to FIG. FIG. 3 is a configuration diagram of a main part of the X-ray focusing apparatus of the second embodiment.

  The X-ray focusing apparatus of this embodiment differs from the first embodiment in the structure of the MCX 20 that is arranged in front of the FZP 3. That is, the MCX2 in the first embodiment has a parallel end at the X-ray exit end, whereas the MCX20 in this embodiment has the X-ray exit end 20c as the focusing end. However, the focal length of the X-ray emission side end 20c is very long. The angle formed between the central axis of the X-rays emitted from each capillary and the central axis of the MCX 20 itself varies depending on the position of the capillary (distance from the central axis), but at most (that is, X emitted from the capillary located on the outermost periphery) The angle with respect to the central axis of the line is 1 ° or less. Therefore, although the X-ray emission side end portion 20c is a converging end, the X-rays emitted from the end face and entering the FZP 3 can be regarded as a substantially parallel bundle. Thereby, as in the first embodiment, X-rays can be focused on the focal point F with high efficiency by FZP3, and leakage of X-rays hardly occurs around the X-rays.

  That is, according to the X-ray focusing apparatus of the first and second embodiments, the X-rays are efficiently collected by the MCX 2 and 20, and the condensed diameter is reduced to a certain extent to form a substantially parallel bundle into a small-diameter FZP3. It can be introduced without waste, and the X-ray can be further focused by FZP3, for example, to irradiate a very small area on the inspection object 11. In this way, even if the intensity of X-rays generated by the X-ray source 12 is not so high, it is possible to irradiate a very small area with high-intensity X-rays.

  In addition, since the said Example is an example of this invention, even if it changes suitably in the range of the meaning of this invention, correction, or addition, it is natural that it is included in the claim of this application.

DESCRIPTION OF SYMBOLS 1 ... X-ray focusing apparatus 10 ... Sample stand 11 ... Test object 12 ... X-ray source 13 ... X-ray detector 2, 20 ... Multicapillary X-ray lens (MCX)
2a, 20a ... X-ray incident side end 2c, 20c ... X-ray emission side end 2b ... Bottleneck shape part 3 ... Fresnel zone plate (FZP)

Claims (3)

a) a plurality of bundled X-ray guiding thin tubes having a parallel portion in which each thin tube is arranged in parallel at least at a part between the X-ray incident side end portion and the X-ray emission side end portion; The X-ray emission side end portion is a parallel end in which the thin tubes are arranged in parallel and the area of the end surface is smaller than the cross-sectional area of the parallel portion, and the parallel portion and the X-ray emission side end portion a capillary assembly inner diameter of the capillary is formed so as to reduce gradually between,
b) A Fresnel zone plate disposed outside the X-ray emission side end of the capillary assembly so that the central axis of the capillary assembly coincides with the central axis;
An X-ray focusing apparatus comprising: The X-ray focusing apparatus according to claim 1,
The X-ray focusing apparatus is characterized in that the X-ray incident side end portion of the narrow tube assembly is a parallel end obtained by extending the parallel portion. a) It is composed of a large number of bundled X-ray guiding thin tubes, and the X-ray emission side end portion is a tube tube assembly that is a focusing end having a focal point at a minute region that can be regarded as one point or a point outside thereof. And an ultra-long focal tube assembly having an angle of 1 ° or less between the axis of the tube located on the outermost periphery at the focusing end and the center axis of the tube assembly;
b) a Fresnel zone plate disposed outside the X-ray emission side end of the capillary tube assembly so that the central axis of the capillary tube assembly coincides with the central axis;
An X-ray focusing apparatus comprising:

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