X-ray spectrometer

Abstract

A first diffraction grating (11) is installed at a first position (P1) and diffracts and spectrally resolves X-rays from an X-ray source (3). A second diffraction grating (12) is installed at a second position (P2) and diffracts and spectrally resolves X-rays from the X-ray source (3). Blocking parts (41, 42) are configured so as to be able to block both a first optical path (71) of the X-rays from the X-ray source (3) diffracted by the first diffraction grating (11) and incident on a detector and a second optical path (72) of the X-rays from the X-ray source (3) diffracted by the second diffraction grating (12) and incident on the detector (2). A control device (91) controls the blocking parts (41, 42) so as to selectively block one of the first optical path (71) and the second optical path (72).

Description

X-ray spectrometer

[0001] The present disclosure relates to X-ray spectroscopy.

[0002] In the spectroscopy of light in the X-ray region, it is difficult to disperse a wide wavelength range using a single diffraction grating from the standpoint of resolution, diffraction efficiency, etc., and therefore multiple diffraction gratings are generally used.

[0003] Japanese Patent No. 5948558 (Patent Document 1) discloses a method of mechanically switching the positions of a plurality of diffraction gratings.

[0004] Patent No. 5948558

[0005] However, mechanically switching the position of the diffraction grating requires interrupting the measurement, which reduces measurement throughput. Furthermore, the mechanical structure required for switching the position of the diffraction grating is complex, requiring high-precision design and manufacturing techniques, which also imposes a significant burden in terms of cost. In response to these issues, there has been a demand for technology that can improve measurement throughput by using multiple diffraction gratings for measurement without mechanically switching the positions of the multiple diffraction gratings.

[0006] The present disclosure has been made to solve such problems, and its purpose is to perform spectroscopic measurement using multiple diffraction gratings without mechanically switching the positions of the multiple diffraction gratings.

[0007] A first aspect of the present invention relates to an X-ray spectrometer including a first diffraction grating, a second diffraction grating, a detector, a blocking unit, and a control device. The first diffraction grating is installed at a first position and diffracts and disperses X-rays from an X-ray source. The second diffraction grating is installed at a second position and diffracts and disperses X-rays from the X-ray source. The detector detects the X-rays diffracted and dispersed by the first diffraction grating and the second diffraction grating. The blocking unit is configured to block a first optical path of X-rays diffracted from the X-ray source by the first diffraction grating and incident on the detector, and a second optical path of X-rays diffracted from the X-ray source by the second diffraction grating and incident on the detector. The control device controls the blocking unit to selectively block one of the first optical path and the second optical path.

[0008] According to the present disclosure, spectroscopic measurements can be performed using multiple diffraction gratings without mechanically switching the positions of the multiple diffraction gratings.

[0009] FIG. 1 is a schematic diagram showing the configuration of an X-ray spectrometer according to embodiment 1. FIG. 2 is a diagram for explaining a first state. FIG. 3 is a diagram for explaining a second state. FIG. 4 is a schematic diagram showing the configuration of an X-ray spectrometer according to embodiment 2. FIG. 5 is a schematic diagram showing the configuration of an X-ray spectrometer according to modified example 1. FIG. 6 is a schematic diagram showing the configuration of an X-ray spectrometer according to modified example 2.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and description thereof will not be repeated.

[0011] [X-ray Spectrometer According to First Embodiment] The X-ray spectrometer 100 according to the first embodiment includes a plurality of diffraction gratings, a detector 2, and a blocking unit. The X-ray spectrometer 100 may be used as part of an X-ray analysis device including an X-ray spectrometer, such as a scanning electron microscope (SEM) or an electron probe micro analyzer (EPMA).

[0012] In one embodiment, the plurality of diffraction gratings includes a first diffraction grating 11 and a second diffraction grating 12. In other embodiments, the plurality of diffraction gratings may include three or more diffraction gratings.

[0013] In the example of FIG. 1 , for convenience of explanation, the position of the X-ray source 3 is taken as the origin, the direction parallel to the line 6 connecting the X-ray source 3 to the detector 2 is taken as the positive X-axis direction, and the plane on which the X-ray source 3, the detector 2, the first diffraction grating 11, and the second diffraction grating 12 exist is taken as the XY plane. The direction perpendicular to the XY plane is taken as the Z-axis direction. The positional relationship between the XY plane and the direction of gravity is not particularly limited. For example, the first diffraction grating 11 and the second diffraction grating 12 may be arranged vertically along the direction of gravity, horizontally perpendicular to the direction of gravity, or in any other positional relationship. Furthermore, the plane on which the X-ray source 3, the detector 2, and the first diffraction grating 11 exist may be the same as or different from the plane on which the X-ray source 3, the detector 2, and the second diffraction grating 12 exist.

[0014] The first diffraction grating 11 is installed at a first position P1 and diffracts and disperses the X-rays from the X-ray source 3. More specifically, the first diffraction grating 11 is configured to diffract and disperse the X-rays from the X-ray source 3 at a first diffraction angle A1. The first diffraction grating 11 has a grating surface 111 for diffracting and dispersing the X-rays. More specifically, the first diffraction grating 11 is fixed to the first position P1, which is a specific coordinate position within the X-ray spectrometer 100 that satisfies the condition "X-rays from the X-ray source 3 are diffracted and disperse at the first diffraction angle A1," and the angle of the grating surface 111 with respect to the line 6 is also fixed to an angle that satisfies this condition.

[0015] The second diffraction grating 12 is installed at a second position P2 and diffracts and disperses the X-rays from the X-ray source 3. More specifically, the second diffraction grating 12 is configured to diffract and disperse the X-rays from the X-ray source 3 at a second diffraction angle A2. The second diffraction grating 12 has a grating surface 121 for diffracting and dispersing the X-rays. More specifically, the second diffraction grating 12 is fixed to the second position P2, which is a specific coordinate position within the X-ray spectrometer 100 that satisfies the condition "X-rays from the X-ray source 3 are diffracted and disperse at the second diffraction angle A2," and the angle of the grating surface 121 with respect to the line 6 is also fixed to an angle that satisfies this condition.

[0016] In this specification, the "diffraction angle" refers to the angle between X-rays incident on the grating surfaces 111 and 121 (incident X-rays) and X-rays diffracted by the grating surfaces 111 and 121 (diffracted X-rays). Those skilled in the art also refer to this diffraction angle as the "deflection angle."

[0017] The second diffraction angle A2 is an angle different from the first diffraction angle A1. In other words, the first diffraction grating 11 and the second diffraction grating 12 have diffraction angles suitable for separating X-rays in different energy ranges (different wavelength regions). Therefore, by selectively using the first diffraction grating 11 and the second diffraction grating 12 depending on the energy range of the X-rays incident from the X-ray source 3, X-rays with higher output and higher resolution can be incident on the detector 2 than when using only one of the diffraction gratings.

[0018] Each of the diffraction gratings 11 and 12 is preferably a non-uniformly spaced groove diffraction grating. The grating surfaces 111 and 121 of the diffraction gratings 11 and 12 may be concave or flat. The grating surfaces 111 and 121 do not necessarily have to lie on the Rowland circle. The characteristics and arrangement of the grating surfaces 111 and 121 are described in more detail below.

[0019] The unevenly spaced groove indirect grating is a diffraction grating in which the grating surfaces 111 and 121 are formed with uneven spacing. More specifically, the unevenly spaced groove indirect grating is a diffraction grating in which the grating surfaces 111 and 121 are arranged in a pattern such that X-rays from the X-ray source 3 can be appropriately dispersed and detected on the detection surface 21 of the detector 2 regardless of the position on the grating surfaces 111 and 121 at which the X-rays are incident. As described above, by using unevenly spaced groove gratings as the diffraction gratings 11 and 12, X-rays from the X-ray source 3 can be appropriately dispersed regardless of the position on each of the grating surfaces 111 and 121 at which the X-rays are incident. Therefore, accurate measurement is possible.

[0020] When variable-groove gratings are used as the diffraction gratings 11 and 12, sufficient resolution can be obtained even if the X-rays from the X-ray source 3 do not form an image on the Rowland circle that passes through the X-ray source 3 and the detector 2. Therefore, the grating surfaces 111 and 121 may be flat and do not have to be located on the Rowland circle. However, since the grating surfaces 111 and 121 only need to be located at positions where the X-rays from the X-ray source 3 are diffracted and dispersed at diffraction angles A1 and A2, respectively, and are incident on the detector 2, the grating surfaces 111 and 121 may be located on or near the Rowland circle as a result of being located at those positions.

[0021] When using diffraction gratings with equally spaced gratings, which have been widely used in the past, as diffraction gratings 11 and 12, it is preferable that the grating surfaces 111 and 121 are concave surfaces, and that the concave surfaces are arranged so as to align with the Rowland circle.

[0022] The X-ray source 3 is a source of X-rays that enter the X-ray spectrometer 100. The X-ray source 3 is disposed at a position where the X-rays emitted from the X-ray source 3 are diffracted and dispersed by the diffraction gratings 11 and 12 and enter the detection surface 21 of the detector 2. The X-ray source may be a point light source or a surface light source.

[0023] Detector 2 detects X-rays diffracted and dispersed by each of first diffraction grating 11 and second diffraction grating 12. Detector 2 has a detection surface 21 that detects incident X-rays. Detection surface 21 detects the X-rays dispersed by diffraction gratings 11 and 12 according to their energy values ​​at positions according to the energy values.

[0024] In one embodiment, the X-ray source 3 is a sample containing the element to be measured. When the sample is irradiated with primary X-rays from an X-ray tube (not shown), characteristic X-rays of the element are emitted from the sample. The characteristic X-rays are diffracted and dispersed by the diffraction gratings 11 and 12, and are imaged on the detection surface 21 at positions corresponding to the energy values ​​of the characteristic X-rays. An X-ray image that appears as stripes on the detection surface 21 at positions corresponding to the energy values, as in this embodiment, is also referred to as a spectrum by those skilled in the art.

[0025] In another embodiment, the X-ray source 3 is an X-ray tube that generates primary X-rays. The primary X-rays are diffracted and dispersed by the diffraction gratings 11 and 12 and detected at positions on the detection surface 21 according to their energy values.

[0026] To summarize the above, in X-ray spectrometer 100, the positional relationship between first diffraction grating 11, detector 2, and X-ray source 3 is determined based on first diffraction angle A1. Furthermore, the positional relationship between second diffraction grating 12, detector 2, and X-ray source 3 is determined based on second diffraction angle A2. In other words, first diffraction grating 11, second diffraction grating 12, detector 2, and X-ray source 3 are arranged so that first diffraction grating 11 and second diffraction grating 12 can diffract and disperse X-rays from X-ray source 3 at first diffraction angle A1 and second diffraction angle A2, respectively, and the X-rays can be incident on detector 2.

[0027] Hereinafter, the optical path of X-rays that are emitted from the X-ray source 3, diffracted by the first diffraction grating 11, and incident on the detector 2 will be referred to as a first optical path 71. The first optical path 71 includes an optical path 711 from the X-ray source 3 to the first diffraction grating 11, and an optical path 712 from the first diffraction grating 11 to the detector 2. The optical path of X-rays that are emitted from the X-ray source 3, diffracted by the second diffraction grating 12, and incident on the detector 2 will be referred to as a second optical path 72. The second optical path 72 includes an optical path 721 from the X-ray source 3 to the second diffraction grating 12, and an optical path 722 from the second diffraction grating 12 to the detector 2.

[0028] The blocking unit is configured to block the first optical path 71 and the second optical path 72. The blocking unit may be configured with one member or multiple members. In one embodiment, the blocking unit generates a first state ( FIG. 2 ) in which the second optical path 72 is blocked and the first optical path 71 is not blocked, and a second state ( FIG. 3 ) in which the first optical path 71 is blocked and the second optical path 72 is not blocked. The blocking unit may block optical path 711 or optical path 712 to block the first optical path 71. The blocking unit may block optical path 721 or optical path 722 to block the second optical path 72.

[0029] In one embodiment, the blocking unit includes a first blocking plate 41 and a second blocking plate 42. In other words, the first blocking plate 41 and the second blocking plate 42 correspond to one embodiment of a "blocking unit." The first blocking plate 41 is, for example, a plate-shaped member made of a material that does not transmit (blocks) X-rays, and can be positioned at a position P411 where it does not block the first optical path 71 and a position P412 where it blocks the first optical path 71. The first blocking plate 41 moves between the positions P411 and P412 by, for example, sliding on a rail (not shown).

[0030] The second shielding plate 42 is, for example, a plate-like member made of a material that does not transmit (blocks) X-rays, and can be positioned at a position P421 where it blocks the second optical path 72 and a position P422 where it does not block the second optical path 72. The second shielding plate 42 moves between the position P421 and the position P422 by, for example, sliding on a rail (not shown).

[0031] 2, the first shielding plate 41 is located at a position P411, and the second shielding plate 42 is located at a position P421. Therefore, a first state is generated in which the second optical path 72 is blocked and the first optical path 71 is not blocked.

[0032] 3, the first shielding plate 41 is located at a position P412, and the second shielding plate 42 is located at a position P422. Therefore, a second state is generated in which the first optical path 71 is blocked and the second optical path 72 is not blocked.

[0033] In one embodiment, the first state and the second state are switched by a control device 91. Note that the illustration of the control device 91 is omitted from Fig. 2 and subsequent figures. The control device 91 controls the blocking unit to selectively block one of the first optical path 71 and the second optical path 72. The control device 91 includes a processor 911 and a memory 912.

[0034] The processor 911 includes, for example, a CPU (Central Processing Unit). The processor 911 reads and executes a program stored in the memory 912 to control the operation of each part of the X-ray spectrometer 100. In one embodiment, the processor 911 controls a moving mechanism (not shown) for the first shielding plate 41 and the second shielding plate 42 to switch between the first state and the second state.

[0035] The memory 912 is realized by a non-volatile storage device such as a read only memory (ROM) or a hard disk. The memory 912 stores programs executed by the processor 911, data used by the processor 911, etc. The programs may be stored in a non-transitory computer-readable medium.

[0036] In another embodiment, the user may manually switch between the first state and the second state. For example, the user may switch the positions of the shielding plates 41, 42 using an input device such as a lever that is linked to the shielding plates 41, 42. For example, a mechanical mechanism that combines the lever with gears, rails, etc. is configured so that the shielding plates 41, 42 move when the lever is moved. However, a configuration in which the processor 911 controls the movement mechanism of the shielding plates 41, 42 to switch between the first state and the second state is preferable because it requires less effort from the user.

[0037] In the X-ray spectrometer 100, a first diffraction grating 11 is used in which the first diffraction angle A1 is preferably 170° or more and less than 180°, and more preferably 170° or more and 179° or less. Also, a second diffraction grating 12 is used in which the second diffraction angle A2 is preferably 170° or more and less than 180°, and more preferably 170° or more and 179° or less.

[0038] By using diffraction gratings with a diffraction angle of 170° or more and less than 180° as the diffraction gratings 11 and 12, X-rays with wavelengths known as soft X-rays can be spectroscoped with high power and high resolution. More specifically, X-rays with energies of 50 eV or more and 5 keV or less can be spectroscoped with high power and high resolution. This makes it possible to efficiently detect X-rays with energies of 4 keV or more and 5 keV or less, which could not be efficiently detected by conventional X-ray spectrometers using diffraction gratings with low reflection efficiency for X-rays of 4 keV or more. Note that X-rays with energies of 50 eV or more and 5 keV or less are, in other words, X-rays with wavelengths of 0.25 nm or more and 25 nm or less.

[0039] Furthermore, by using diffraction gratings with a diffraction angle of 170° or more and less than 180° as the diffraction gratings 11 and 12, X-rays can be detected with sufficient wavelength resolution in the first and second states without changing the orientation of the detection surface 21 of the detector 2 in the X-ray spectrometer 100. This point will be described in more detail below.

[0040] When the first diffraction angle is equal to or greater than 170° and less than 180°, the incident angle B1 (the angle between the line 6 and the optical path 712) of the X-rays on the detector 2 in the first state is approximately 5 degrees or less. Therefore, even if the detector 2 is positioned so that the line 6 and the detection surface 21 are perpendicular, as shown in FIGS. 1 to 3 , the spectral broadening on the detection surface 21 due to the incident angle B1 is slight and does not affect the wavelength resolution. Specifically, if the spectral width when the detector 2 is positioned so that the incident angle is 0° (the optical path 712 and the detection surface 21 are perpendicular) is 1, the spectral width when the incident angle is 5° is 1 / cosB = 1 / cos(5°) = 1.00382. Therefore, when the incident angle is approximately 5° or less, the spectral broadening due to the non-zero incident angle is only approximately 1.00382 times or less. Therefore, in the first state, X-rays can be detected with sufficient wavelength resolution without changing the orientation of the detection surface 21 of the detector 2 so that the optical path 712 and the detection surface 21 are perpendicular to each other.

[0041] Similarly, when the second diffraction angle is greater than or equal to 170° and less than or equal to 179°, in the second state, X-rays can be detected with sufficient wavelength resolution without changing the orientation of the detection surface 21 of the detector 2 so that the optical path 722 and the detection surface 21 are perpendicular to each other.

[0042] As described above, in both the first state and the second state, X-rays can be detected with sufficient resolution even if the detector 2 is positioned so that the line 6 shown in FIG. 2 is perpendicular to the detection surface 21. Therefore, by fixing the angle of the detection surface 21 with respect to the line 6 connecting the X-ray source 3 and the detector 2 throughout the first and second states, it is possible to omit a mechanism for changing the angle of the detection surface 21 while maintaining sufficient resolution. This prevents the configuration of the X-ray spectrometer 100 from becoming complicated.

[0043] As described above, in the X-ray spectrometer 100 according to this embodiment, X-rays diffracted and dispersed by each of the plurality of diffraction gratings fixed at a plurality of predetermined positions can be selectively incident on the detector 2. Therefore, spectroscopic measurement can be performed using the plurality of diffraction gratings without mechanically switching the positions of the plurality of diffraction gratings.

[0044] [Comparison with Conventional X-ray Spectrometers] Conventional X-ray spectrometers, as disclosed in Patent Document 1, have been configured to mechanically switch the positions of multiple diffraction gratings. However, mechanically switching the position of the diffraction gratings requires interrupting the measurement. Furthermore, if the diffraction grating is positioned off-center for diffraction and spectroscopy when switching its position, the diffraction grating and / or detector must be repositioned. As shown in FIG. 1 , the position and angle of each diffraction grating relative to the light source and detector in the X-ray spectrometer must be adjusted to satisfy the diffraction angle specific to that diffraction grating. Therefore, for accurate spectroscopic measurements, the position and angle of the diffraction grating must be precisely set. Furthermore, if the position and angle deviate from the set position and angle, precise alignment is required, which is time-consuming and labor-intensive. As described above, conventional configurations can reduce the throughput of spectroscopic measurements.

[0045] Furthermore, in conventional configurations, the mechanical structure for switching the position of the diffraction grating is complex, which requires high-precision design and manufacturing techniques, which increases the manufacturing costs of the X-ray spectrometer.

[0046] Therefore, in the X-ray spectrometer 100 according to this embodiment, each of the multiple diffraction gratings is fixed at a predetermined position within the X-ray spectrometer 100, and the diffraction grating used for measurement is switched using the blocking section, thereby making it possible to perform X-ray measurement using the multiple diffraction gratings without mechanically switching the positions of the multiple diffraction gratings. Therefore, highly accurate spectroscopic measurement can be achieved in an X-ray spectrometer with a simple structure.

[0047] As shown in FIGS. 1 to 3 , the X-ray spectrometer 100 according to this embodiment also requires switching the position of the blocking sections (shielding plates 41, 42). However, switching the position of the blocking sections only requires consideration of whether or not to block the X-ray optical path, and does not require precise position adjustment. Therefore, the X-ray spectrometer 100 according to this embodiment does not suffer from a decrease in throughput due to detailed position adjustment of the blocking sections, nor does it require high-precision design and manufacturing techniques. Furthermore, when switching between the use of the diffraction gratings 11 and 12, light from the X-ray source 3 does not leak to areas other than the diffraction gratings 11 and 12, so there is no need to stop the emission of X-rays from the X-ray source 3 and interrupt the measurement. As described above, a decrease in throughput can be suppressed while maintaining measurement accuracy.

[0048] 4 is a schematic diagram showing the configuration of an X-ray spectrometer 100A according to embodiment 2. The X-ray spectrometer 100A includes a chopper 49 as a blocking unit, instead of the shielding plates 41 and 42 in the X-ray spectrometer 100 according to embodiment 1. In other words, the chopper 49 corresponds to one example of a "blocking unit."

[0049] In one embodiment, the chopper 49 is a disk-shaped member made of a material that is opaque to X-rays. The chopper 49 rotates around a central axis 491. In the chopper 49, grooves 492 are formed on the side of the disk in a direction from the circumference toward the central axis 491, and the grooves 492 are used as slits that allow X-rays to pass intermittently. As a more specific example, the chopper 49 has a general gear shape.

[0050] In this embodiment, the chopper 49 is positioned to rotate to successively block the first optical path 71 and the second optical path 72. Specifically, the chopper 49 rotates to repeatedly switch between a first state in which the second optical path 72 is blocked by the chopper 49 and the first optical path 71 passes through the slit, and a second state in which the first optical path 71 is blocked by the chopper 49 and the second optical path 72 passes through the slit.

[0051] However, the shape of the chopper 49 only needs to be such that it can generate a first state in which the second optical path 72 is blocked and the first optical path 71 is not blocked, and a second state in which the first optical path 71 is blocked and the second optical path 72 is not blocked, and any shape that is used as a chopper by those skilled in the art will suffice.

[0052] According to the X-ray spectrometer 100A of the second embodiment, by rotating the chopper 49 at a predetermined speed, it is possible to continuously and rapidly switch between measurements using the first diffraction grating 11 and measurements using the second diffraction grating 12. In other words, measurements using the first diffraction grating 11 and measurements using the second diffraction grating 12 can be alternately repeated for very short periods of time. Therefore, measurements using the first diffraction grating 11 and measurements using the second diffraction grating 12 can be performed almost simultaneously with almost no time lag. Furthermore, there is no need to control the individual movements of the first shielding plate 41 and the second shielding plate 42 as in the first embodiment; it is sufficient to simply rotate the chopper at a predetermined speed. On the other hand, in the X-ray spectrometer 100A, the groove 492 of the chopper 49 needs to be positioned so that the first optical path 71 and the second optical path 72 pass through alternately, whereas in the X-ray spectrometer 100, the positioning of the first shielding plate 41 and the second shielding plate 42 is more approximate, and it is sufficient that the first optical path 71 and the second optical path 72 are blocked by any part of the first shielding plate 41 and any part of the second shielding plate, respectively. As described above, the X-ray spectrometer 100 has the advantage that the positioning of the blocking parts can be more approximate.

[0053] 5 is a schematic diagram showing the configuration of an X-ray spectrometer 100B according to Modification 1. The X-ray spectrometer 100B includes a first slit 51 and a second slit 52 in addition to the configuration of the X-ray spectrometer 100 according to the first embodiment.

[0054] In one embodiment, the slits 51 and 52 are Soller slits, which are made of a number of thin plates made of a material that is opaque to X-rays and arranged in parallel at predetermined intervals. By passing X-rays through the Soller slits, it is possible to limit the divergence of the X-rays in a direction perpendicular to the thin plates. Therefore, the use of Soller slits makes it possible to limit the angle of incidence of X-rays on the grating surfaces 111 and 121. In other words, only X-rays that are incident on the grating surfaces 111 and 121 at a predetermined angle that passes through the Soller slits can be allowed to pass through. Furthermore, only X-rays emitted from predetermined positions on the X-ray source 3 corresponding to the Soller slits are incident on the grating surfaces 111 and 121.

[0055] In another embodiment, the slits 51 and 52 are slits formed in a plate-like member made of a material that does not transmit X-rays, with holes formed therein that allow X-rays to pass through. When the holes are circular and have a relatively small diameter, they are also called pinhole slits. Using a pinhole slit allows only X-rays emitted from a predetermined position on the X-ray source 3 corresponding to the hole to pass through, while blocking X-rays generated outside the predetermined range. This allows only X-rays emitted from the predetermined position on the X-ray source 3 at a predetermined angle that passes through the pinhole slit hole to be incident on the grating surfaces 111 and 121.

[0056] As described above, by using the slits 51 and 52, only X-rays emitted at a predetermined angle from a predetermined position of the X-ray source 3 can be incident on the grating surfaces 111 and 121. Therefore, the X-rays can be dispersed accurately according to their wavelengths on the grating surfaces 111 and 121. This improves the measurement accuracy of the X-ray spectrometer 100B.

[0057] In particular, when the X-ray source 3 is a surface light source, the provision of the slits 51 and 52 is advantageous in that it can prevent X-rays generated from various positions on the surface light source from being incident on the grating surfaces 111 and 121 at various angles.

[0058] [X-ray Spectrometer According to Modification 2] As described above, the plurality of diffraction gratings may include three or more diffraction gratings. Below, as Modification 2, an example including three diffraction gratings will be shown.

[0059] 6 is a schematic diagram showing the configuration of an X-ray spectrometer according to Modification 2. The X-ray spectrometer 100C includes a third diffraction grating 13 and a third shielding plate 43 in addition to the configuration of the X-ray spectrometer 100 according to Embodiment 1.

[0060] The third diffraction grating 13 is installed at a third position P3 and diffracts and disperses the X-rays from the X-ray source 3. More specifically, the third diffraction grating 13 is configured to diffract and disperse the X-rays from the X-ray source 3 at a third diffraction angle A3. The third diffraction grating 13 has a grating surface 131 for diffracting and dispersing the X-rays. More specifically, the third diffraction grating 13 is fixed to the third position P3, which is a specific coordinate position within the X-ray spectrometer 100 that satisfies the condition "X-rays from the X-ray source 3 are diffracted and disperse at the third diffraction angle A3," and the angle of the grating surface 131 with respect to the line 6 is also fixed to an angle that satisfies this condition. Preferably, the third diffraction angle A3 is equal to or greater than 170° and less than 180°, and more preferably, a third diffraction grating 13 whose third diffraction angle A3 is equal to or greater than 170° and less than 179° is used.

[0061] In the second modification, the blocking unit includes a third blocking plate 43 in addition to the first blocking plate 41 and the second blocking plate 42. The third blocking plate 43 is, for example, a plate-shaped member formed of a material that does not transmit (blocks) X-rays, and can be positioned at a position P433 where it does not block the third optical path 73, and a position P434 where it blocks the third optical path 73. The third blocking plate 43 moves between positions P433 and P434 by, for example, sliding on a rail (not shown). Note that the third blocking plate 43 may block either optical path 731 or optical path 732 in order to block the third optical path 73.

[0062] The control device 91 controls the blocking unit to selectively block the first optical path 71, the second optical path 72, and the third optical path 73. For example, in Fig. 6, the blocking unit blocks each of the first optical path 71 and the second optical path 72, but does not block the third optical path 73.

[0063] The third diffraction angle A3 is different from the first diffraction angle A1 and the second diffraction angle A2. In other words, the first diffraction grating 11, the second diffraction grating 12, and the third diffraction grating 13 have diffraction angles suitable for separating X-rays in different energy ranges (different wavelength regions). Therefore, by using three diffraction gratings depending on the energy range of the X-rays incident from the X-ray source 3, X-rays with higher output and resolution can be incident on the detector 2 than when using two diffraction gratings. As described above, by increasing the number of diffraction gratings with different diffraction angles, the measurement accuracy can be further improved.

[0064] Aspects It will be understood by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0065] (Item 1) An X-ray spectrometer according to one aspect includes a first diffraction grating, a second diffraction grating, a detector, a blocking unit, and a control device. The first diffraction grating is installed at a first position and diffracts and disperses X-rays from an X-ray source. The second diffraction grating is installed at a second position and diffracts and disperses X-rays from the X-ray source. The detector detects X-rays diffracted and dispersed by the first diffraction grating and the second diffraction grating. The blocking unit is configured to block a first optical path of X-rays diffracted from the X-ray source by the first diffraction grating and incident on the detector, and a second optical path of X-rays diffracted from the X-ray source by the second diffraction grating and incident on the detector. The control device controls the blocking unit to selectively block one of the first optical path and the second optical path.

[0066] According to the X-ray spectrometer described in paragraph 1, X-rays diffracted and dispersed by each of a plurality of diffraction gratings fixed at a plurality of predetermined positions can be selectively incident on a detector, thereby making it possible to perform spectroscopic measurement using a plurality of diffraction gratings without mechanically switching the positions of the plurality of diffraction gratings.

[0067] (Item 2) In the X-ray spectrometer described in item 1, the first diffraction grating diffracts and disperses the X-rays from the X-ray source at a first diffraction angle. The second diffraction grating diffracts and disperses the X-rays from the X-ray source at a second diffraction angle. Each of the first diffraction angle and the second diffraction angle is equal to or greater than 170° and less than 180°.

[0068] According to the X-ray spectrometer described in paragraph 2, X-rays with an energy of 50 eV or more and 5 keV or less can be spectroscoped with high output and high resolution.

[0069] (Item 3) In the X-ray spectrometer described in item 2, the detector has a detection surface that detects incident X-rays. The angle of the detection surface with respect to a line connecting the X-ray source and the detector is fixed.

[0070] According to the X-ray spectrometer described in the third aspect, it is possible to omit the mechanism for changing the angle of the detection surface.

[0071] (4) In the X-ray spectrometer according to any one of the first to third aspects, the blocking section includes a chopper.

[0072] According to the X-ray spectrometer described in item 4, the measurement using the first diffraction grating and the measurement using the second diffraction grating can be carried out almost simultaneously with almost no time lag.

[0073] (Item 5) In the X-ray spectrometer described in any one of items 1 to 4, the blocking section includes a first blocking plate and a second blocking plate.

[0074] According to the X-ray spectrometer described in item 5, the positioning of the blocking portion may be more roughly determined. (Item 6) The X-ray spectrometer described in any one of items 1 to 5 further includes a first slit in the first optical path and a second slit in the second optical path.

[0075] According to the X-ray spectrometer described in paragraph 6, only X-rays emitted from a predetermined position of the X-ray source at a predetermined angle can be incident on the grating surface, thereby enabling the X-rays to be separated on the grating surface with high precision according to their wavelengths.

[0076] (Item 7) In the X-ray spectrometer described in any one of Items 1 to 6, each of the first diffraction grating and the second diffraction grating is an irregularly spaced groove diffraction grating.

[0077] According to the X-ray spectrometer described in item 7, X-rays from the X-ray source can be dispersed appropriately regardless of the position on each grating surface where the X-rays are incident, and therefore measurements can be made with high accuracy.

[0078] (Item 8) The X-ray spectrometer according to any one of Items 1 to 7 further includes a third diffraction grating disposed at a third position for diffracting and dispersing X-rays from the X-ray source. The blocking unit is further configured to block a third optical path of X-rays diffracted by the third diffraction grating from the X-ray source and incident on the detector. The control device controls the blocking unit to selectively block the first optical path, the second optical path, and the third optical path.

[0079] According to the X-ray spectrometer described in item 8, the measurement accuracy can be further improved compared to the case where two diffraction gratings are used.

[0080] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0081] 2 Detector, 3 X-ray source, 6 Line, 11 First diffraction grating, 12 Second diffraction grating, 13 Third diffraction grating, 21 Detection surface, 41 First shielding plate, 42 Second shielding plate, 49 Chopper, 51 First slit, 52 Second slit, 71 First optical path, 72 Second optical path, 73 Third optical path, 91 Control device, 100, 100A, 100B, 100C X-ray spectrometer, 111, 121, 131 Grating surface, 491 Central axis, 492 Groove, 711, 712, 721, 722, 731, 732 Optical path, 911 Processor, 912 Memory, A1 First diffraction angle, A2 Second diffraction angle, A3 Third diffraction angle, B1 Incident angle, P1 First position, P2 Second position, P3 3rd position, P411, P412, P421, P422, P433, P434 position.

Claims

1. An X-ray spectrometer comprising: a first diffraction grating installed at a first position for diffracting and dispersing X-rays from an X-ray source; a second diffraction grating installed at a second position for diffracting and dispersing X-rays from the X-ray source; a detector for detecting X-rays diffracted and dispersed by each of the first diffraction grating and the second diffraction grating; a blocking portion configured to be able to block a first optical path of X-rays diffracted by the first diffraction grating from the X-ray source and incident on the detector, and a second optical path of X-rays diffracted by the second diffraction grating from the X-ray source and incident on the detector; and a control device for controlling the blocking portion to selectively block one of the first optical path and the second optical path.

2. The X-ray spectrometer according to claim 1, wherein the first diffraction grating diffracts and disperses X-rays from the X-ray source at a first diffraction angle, the second diffraction grating diffracts and disperses X-rays from the X-ray source at a second diffraction angle, and each of the first diffraction angle and the second diffraction angle is 170° or more and less than 180°.

3. The X-ray spectrometer according to claim 2, wherein the detector has a detection surface for detecting incident X-rays, and an angle of the detection surface with respect to a straight line connecting the X-ray source and the detector is fixed.

4. The X-ray spectrometer according to claim 1, wherein the blocking portion includes a chopper.

5. The X-ray spectrometer according to claim 1, wherein the blocking portion includes a first shielding plate and a second shielding plate.

6. The X-ray spectrometer according to claim 1, further comprising a first slit in the first optical path and a second slit in the second optical path.

7. The X-ray spectrometer according to claim 1, wherein each of the first diffraction grating and the second diffraction grating is an unequal pitch groove diffraction grating.

8. The X-ray spectrometer according to claim 1, further comprising a third diffraction grating installed at a third position for diffracting and dispersing X-rays from the X-ray source, wherein the blocking portion is further configured to be able to block a third optical path of X-rays diffracted by the third diffraction grating from the X-ray source and incident on the detector, and the control device controls the blocking portion to selectively block the first optical path, the second optical path, and the third optical path.

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