JP2014085267A - X-ray analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray analyzer capable of performing simple mapping analysis by changing a position on a sample to radiate excitation X-rays with a simple structure and without moving the sample.SOLUTION: A collimator part 3 between an X-ray tube 2 and a sample W is composed of plural collimator plates 31 and 32. Movement mechanisms 41 and 42 are provided for moving the collimator plates 31 and 32 in synchronization with each other so that the center of each open hole 31a and 32a is positioned on a line connecting an X-ray focal point 1a and an arbitrary point on the sample W. This configuration suppresses a shadow of X-rays when the line connecting the X-ray focal point 1a and a point on the sample W and an axis line of the open holes 31a and 32a of the collimator part 3 are oblique.

Description

  The present invention relates to an X-ray analyzer, and more particularly to an X-ray analyzer having a simple mapping function.

  In an X-ray analyzer, generally, fluorescent X-rays (characteristic X-rays) generated by irradiating a sample with excitation X-rays are detected, and energy (wavelength) and intensity (dose) of the fluorescent X-rays are obtained. . Since fluorescent X-rays (characteristic X-rays) emitted from a sample have energy (wavelength) specific to the element, it is possible to identify the elements contained in the sample by obtaining the energy (wavelength) of the fluorescent X-rays. And the concentration of the element can be known from the intensity (dose).

  The X-ray analyzer is classified into an energy dispersion type and a wavelength dispersion type depending on how to analyze the energy (wavelength) of fluorescent X-rays. In an energy dispersive X-ray analyzer, fluorescent X-rays emitted from a sample are directly detected by an X-ray detector such as a semiconductor detector, and the detected output wave height is correlated with the X-ray energy. Utilizing this, the output signal of the X-ray detector is discriminated from the wave height to determine the wave height, and hence the dose for each energy. On the other hand, in a wavelength dispersive X-ray analyzer, fluorescent X-rays emitted from a sample are dispersed for each wavelength using a spectral crystal or the like, and an X-ray dose at each wavelength is detected.

  In the X-ray analysis apparatus as described above, a technique called mapping analysis is known. In the mapping analysis, the X-ray irradiation position on the sample is sequentially changed, the fluorescent X-rays are detected at each X-ray irradiation position, and the analysis as described above is performed, whereby the element concentration distribution at each position of the sample is determined. This is the analysis method to be sought.

  In order to perform such a mapping analysis, a sample is usually fixed on a moving mechanism such as an xy stage, and a certain X-ray irradiation position of X-rays for excitation from an X-ray tube is driven by the moving mechanism. The structure which moves a sample with respect to is employ | adopted.

  An example of an energy dispersive X-ray analysis apparatus is shown in FIG. The sample W is positioned and fixed on the xy stage 101, and X-rays from the X-ray tube 102 are irradiated to the sample W as excitation X-rays 108 through the collimator 103. The fluorescent X-ray 109 emitted from the sample W by this irradiation enters the X-ray detector 106 and is detected. The output of the X-ray detector 106 is taken into a measurement circuit 107 such as a multi-channel analyzer, amplified, and then subjected to wave height analysis and counting of signals at each wave height.

  The xy stage 101 is driven and controlled by the stage controller 110, and moves and positions the sample W so that the irradiation position of the excitation X-ray 108 on the sample W sequentially changes within a preset range ( For example, see Patent Document 1).

  Thus, in order to fix the irradiation position of the excitation X-ray and move the sample W side, an xy stage is required. In particular, in a configuration that can handle a relatively large sample, As a technique for solving this problem, a technique for changing the irradiation position of the excitation X-ray on the sample by moving the collimator has already been proposed (for example, a patent). Reference 2).

  That is, in the technique disclosed in Patent Document 2, the X-ray tube and the sample are fixed, and a collimator having a through hole provided between them is moved to move the sample on the sample. The X-ray irradiation position is changed.

JP-A-11-264806 JP 2003-207467 A

  By the way, the configuration in which mapping is performed by providing an xy stage for moving the sample becomes large as described above, and at the same time, even when simple mapping is desired, the sample is fixed on the xy stage. There is also a problem that quick and simple mapping cannot be performed.

  On the other hand, in the technique described in Patent Document 2 in which the irradiation position of the excitation X-ray is changed by moving the collimator, the X-ray shadow by the collimator is generated depending on the irradiation position of the excitation X-ray. There is a problem that the X-ray irradiation area becomes narrow.

That is, the collimator used in this type of analyzer is a collimator body having a predetermined thickness and having a through-hole formed therein, but the collimator is a member for originally forming a parallel light beam. If the thickness of the main body is thin, the spread of X-rays radiated from the focal point of the X-ray tube cannot be suppressed and not only can not function as a collimator, but also the function of shielding X-rays is reduced. To do.
For this reason, the collimator body must have a certain thickness or more. However, if the irradiation position of the excitation X-ray is changed by moving the collimator in parallel, depending on the irradiation position, the X-ray tube The axis of the collimator through-hole is not parallel to the line connecting the focal point of the sample and the X-ray irradiation position of the sample, and the X-ray from the X-ray focal point is oblique to the through-hole having a length corresponding to the thickness of the collimator As a result, the X-ray is shielded by the inner wall of the through-hole, resulting in a problem that the X-ray irradiation area to the sample becomes narrow.

  Patent Document 2 points out the existence of this problem, and describes a method of moving the collimator in an arc shape around the X-ray focal point as a countermeasure.

  However, in order to move the collimator in an arc around the X-ray focal point, a mechanism for moving the collimator in an arc around the X-ray focal point is required, which is extremely complicated and requires a large apparatus configuration. Rather than adopting a conventional mechanism for moving the sample on the xy stage, the apparatus configuration is rather simple.

  The present invention has been made in view of such circumstances, and can perform simple mapping analysis by changing the irradiation position of the excitation X-ray on the sample with a simple configuration without moving the sample. In addition, an object of the present invention is to provide an X-ray analyzer that can suppress the shadowing of excitation X-rays.

  In order to solve the above problems, an X-ray analyzer of the present invention irradiates a sample with X-rays from an X-ray tube via a collimator unit, and the X-ray detector generates fluorescent X-rays generated by the irradiation. In the X-ray analyzer that detects and obtains information related to the element contained in the sample from the detection result, the collimator unit is composed of a plurality of flat collimator plates each having a through hole in the plate thickness direction, Each of these collimator plates is arranged in parallel to each other, and each collimator plate is configured to be movable on a plane along the spreading direction of each plate by driving an individual moving mechanism. The moving mechanism is interlocked by the control means so that the center of the through hole of each collimator plate is located on a line connecting the focal point of the X-ray tube and an arbitrary point on the sample. It is driven and controlled by the movement of each collimator plate, characterized by being configured to move the irradiation position of the sample of X-rays from the X-ray tube.

  The present invention provides a collimator that is provided between an X-ray tube and a sample to narrow the excitation X-ray to a required irradiation area on the sample and to make the X-ray substantially parallel at the same time. The collimator body is not formed with a through-hole as in the above, but is constituted by a plurality of collimator plates each having a through-hole in the thickness direction, and each of these collimator plates is moved in conjunction with each other. Thus, the problem is to be solved by arranging the through holes of the collimator plates along a line connecting the focal point of the X-ray tube and one point on the sample.

  That is, when each collimator plate in which each through-hole is formed is moved in conjunction with each other so that the center of each through-hole is located on a line connecting the X-ray focal point and an arbitrary point on the sample, A set of through holes of each collimator plate is in a state close to one through hole that exists obliquely toward the X-ray focal point. Thereby, it is possible to suppress the occurrence of X-ray shading as in the prior art in which the irradiation position of the excitation X-ray on the sample is changed by translating one through-hole.

  Therefore, according to the configuration of the present invention, it is possible to suppress the occurrence of X-ray shadowing due to the inner wall of the through-hole of the collimator while changing the irradiation position of the excitation X-ray on the sample by the movement of the collimator. This makes it possible to perform a simple mapping analysis under a simple configuration.

  According to the present invention, a plurality of collimator plates are interlocked with each other, and the center of the through hole of each collimator plate is arranged on the line connecting the X-ray irradiation position on the sample and the X-ray focal point, and excitation on the sample Since the X-ray irradiation position is changed, a simple mapping analysis can be performed without providing an xy stage for moving the sample, and the apparatus configuration can be made compact. Since the mapping analysis can be performed by simply placing the sample on the sample plate without being fixed, the mapping analysis can be performed quickly.

  Moreover, when one collimator having a required thickness is moved on a plane as in the prior art, the line connecting the X-ray focal point and the X-ray irradiation position on the sample and the axis of the collimator through-hole are parallel to each other. It is possible to suppress the shadowing of X-rays that is caused by the fact that it is not. In order to prevent the shadow of X-rays, the effect of suppressing shadows is not perfect, but the device configuration is greatly simplified compared to the countermeasure technology that displaces one collimator in an arc shape around the X-ray focal point. Can be

The principal part block diagram of embodiment of this invention. Action explanatory drawing of embodiment of this invention. FIG. 3 is an operation explanatory diagram as a comparative example of FIG. 2, illustrating the occurrence of X-ray shading when one collimator having a required thickness is moved in a plane. The principal part block diagram of the conventional X-ray-analysis apparatus which has a mapping analysis function which moves a sample by xy stage.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a main part of an embodiment of the present invention, and shows a schematic diagram showing a mechanical configuration and a block diagram showing a system configuration.

  The sample W is used for analysis in a state where it is placed on the sample pan 1. The sample dish 1 is provided with a hollow portion 1a, and the sample W is placed on the sample plate 1 so as to close the hollow portion 1a, and the excitation X-ray 8 passes through the hollow portion 1a. Irradiated toward the bottom surface.

  The excitation X-ray 8 allows the X-ray from the X-ray tube 2 to pass through the collimator unit 3, thereby narrowing the X-ray irradiation area on the surface of the sample W to a required size and substantially parallel. X-rays formed into a simple wire bundle. By irradiating the sample W with the excitation X-ray 8, the fluorescent X-ray 9 emitted from the sample W is detected by the X-ray detector 6 made of a semiconductor detector. The output of the X-ray detector 6 is taken into a measurement circuit 7 mainly composed of a multi-channel analyzer (MCA: Multi-Channel Analyzer), and after discrimination of the wave height, the signal of each wave height (energy) is obtained. And are used for analysis of elements contained in the sample W and their concentrations.

  The feature of this embodiment lies in the configuration of the collimator unit 3, and in this example, two parallel collimator plates 31, each having through holes 31a and 32a extending in the thickness direction, are formed. 32. The collimator plates 31 and 32 are individually displaced on the planes along the spreading direction by the moving mechanisms 41 and 42 provided corresponding to the collimator plates 31 and 32, respectively. That is, each of the moving mechanisms 41 and 42 can support the corresponding collimator plates 31 and 32 and move them in the biaxial directions perpendicular to each other indicated by x and y in the drawing.

  The movement mechanisms 41 and 42 are driven and controlled by a control signal supplied from the drive control unit 5 and give displacement to the collimator plates 31 and 32 in conjunction with each other as described below.

  That is, the collimator plates 31 and 32 are displaced so that the through holes 31a and 32a are positioned on a line connecting the focal point 2a of the X-ray tube 2 and an arbitrary point on the sample W. And by giving the displacement which interlock | cooperated as mentioned above with respect to each of these collimator plates 31 and 32, while changing the irradiation position of the X-ray 8 for excitation on the sample W sequentially, the fluorescence in each irradiation position By detecting the X-ray 9 with the X-ray detector 6, mapping analysis, that is, the element present at each irradiation position and its concentration are obtained.

  In the above-described embodiment, a particularly remarkable point is that the collimator unit 3 is constituted by two collimator plates 31 and 32 that are displaced in conjunction with each other, and the through holes 31a and 32a of the collimator plates 31 and 32 are provided. The collimator plates 31 and 32 are displaced so as to be always located on a line connecting the X-ray focal point 2a and an arbitrary point on the sample W, and thereby irradiation of the excitation X-ray 8 on the sample W is performed. This is a point to change the position, and thereby it is possible to suppress the shadow of the excitation X-ray 8 by moving the collimator unit 3 on a plane. The operation will be described below.

  FIG. 2 is an operation explanatory view of the collimator unit 3 used in the embodiment of the present invention. In FIG. 2, for convenience of explanation, the collimator plates 31 and 32 and the surface of the sample W are made parallel, but the result is the same even if they are non-parallel as shown in FIG. 1.

  As shown in FIG. 2A, the line L1 connecting the point P1 on the sample W to be irradiated with the excitation X-ray 8 and the X-ray focal point 1a is orthogonal to the collimator plates 31 and 32. When moving to a point P2 as shown in FIG. 5B, the centers of the through holes 31a and 32a of the collimator plates 31 and 32 are located on a line L2 connecting the point P2 and the X-ray focal point 1a. The collimator plates 31 and 32 are moved as described above. In this state, the excitation X-ray 8 is slightly shaded because the axis of each through-hole 31a, 32a is not exactly along the line L2, and the X-ray irradiation region B on the sample W is shown in FIG. Although slightly smaller than the irradiation area A in a), the amount of shading is greatly reduced as compared with the case where one collimator having the total thickness of the collimator plates 31 and 32 is used.

  That is, FIG. 3 uses the same collimator 300 having the total thickness of the collimator plates 31 and 32 in FIG. 2 and moves the collimator 300 to move the collimator 300 to the same point P2 as in FIG. It is explanatory drawing in the case of irradiating X-rays 8 for excitation. The through holes 300a of the collimator 300 in FIG. 3 have the same size as the through holes 31a and 32a of the collimator plates 31 and 32 in FIG. As is clear from this figure, the excitation X-ray 8 is irradiated toward the point P2 by positioning the center of the through hole 300a of the collimator 300 on the line L2 connecting the point P2 and the X-ray focal point 1a. However, at this time, the excitation X-ray 8 is shaded due to the through hole 300a being inclined with respect to the line L2, and the X-ray irradiation region C on the sample W is formed. Get smaller. Compared with this irradiation region C and the irradiation region B in FIG. 2B when the excitation X-ray 8 is irradiated toward the same point P2 in the embodiment of the present invention, the irradiation region B becomes the irradiation region C. It can be seen that it is relatively large. That is, the effect of suppressing the shadow of the excitation X-ray 8 according to the embodiment of the present invention is clear.

  In the above embodiment, the example in which the two collimator plates 31 and 32 are used in the collimator unit 3 has been described. However, the collimator plates may be arbitrarily plural.

  In the above-described embodiment, the collimator plates 31 and 32 are arranged with a gap therebetween, but may be arranged in a state where they are in close contact with each other.

  Furthermore, in the above embodiment, an example in which the sample W is placed on the sample dish 1 having the punched portion 1a and the excitation X-ray 8 is irradiated toward the lower surface of the sample W through the punched portion 1a. However, it is needless to say that a configuration in which excitation X-rays are irradiated toward the upper surface of the sample can be adopted.

  Furthermore, in the above-described embodiment, an example in which the present invention is applied to an energy dispersive X-ray analyzer has been shown. However, it goes without saying that the present invention can be equally applied to a wavelength dispersive X-ray analyzer. Yes.

DESCRIPTION OF SYMBOLS 1 Sample pan 1a Drilled-out part 2 X-ray tube 2a X-ray focus 3 Collimator part 31, 32 Collimator plate 31a, 32a Through-hole 41, 42 Movement mechanism 5 Drive control part 6 X-ray detector 7 Measurement circuit 8 Excitation X Line 9 Fluorescent X-ray W Sample

Claims (1)

X-rays from an X-ray tube are irradiated onto a sample via a collimator unit, fluorescent X-rays generated by the irradiation are detected by an X-ray detector, and information relating to elements contained in the sample is obtained from the detection result X In the line analyzer,
The collimator section is composed of a plurality of flat collimator plates each formed with a through-hole in the plate thickness direction. These collimator plates are arranged in parallel to each other, and each collimator plate is an individual moving mechanism. The movement mechanism is configured so that the center of the through-hole of each collimator plate is the focal point of the X-ray tube and the sample. Driven and controlled by the control means so as to be positioned on a line connecting any one point above, the position of X-ray irradiation from the X-ray tube to the sample is moved by the movement of each collimator plate. An X-ray analyzer characterized by being configured as described above.

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