Transmission x-ray inspecting device, and transmission x-ray inspecting method

Abstract

The present invention provides a transmission X-ray inspecting device having improved detection sensitivity with respect to foreign matter in a specimen, the transmission X-ray inspecting device comprising: an X-ray source 2 for emitting X-rays including a plurality of mutually different energy ranges; an optical element 3 for dispersing X-rays in one energy range from the X-rays, and condensing the same toward a specimen W; and a transmitted X-ray detector 4 for detecting transmitted X-rays that have been transmitted through the specimen W.

Description

Transmission X-ray inspection device and transmission X-ray inspection method

[0001] The present invention relates to a transmission X-ray inspection apparatus and a transmission X-ray inspection method.

[0002] Conventionally, a system for inspecting a sample for foreign matter has used a transmission X-ray inspection device, as shown in Patent Document 1. This transmission X-ray inspection device irradiates a sample with X-rays from an X-ray generator and detects the transmitted X-rays that have passed through the sample to inspect for foreign matter.

[0003] However, because the X-rays from the X-ray generator irradiate the sample while spreading, the intensity of the X-rays irradiated onto the sample is weak, and as a result, the intensity of the transmitted X-rays that pass through the sample is also weak. This reduces the detection sensitivity of the transmission X-ray detector. While it is possible to increase the counting time to increase the integrated dose in order to improve the detection sensitivity of the transmission X-ray detector, this would increase the time required to inspect each sample for foreign matter.

[0004] Japanese Patent Application Laid-Open No. 2018-141736

[0005] The present invention has been made in view of the above-mentioned problems, and its main object is to improve the detection sensitivity of foreign matter in a sample in a transmission X-ray inspection apparatus.

[0006] That is, the transmission X-ray inspection device according to the present invention is characterized by comprising an X-ray source that emits X-rays including a plurality of mutually different energy ranges, an optical element that splits the X-rays into X-rays of one energy range and focuses the X-rays toward a sample, and a transmission X-ray detection unit that detects the transmitted X-rays that have passed through the sample.

[0007] With this configuration, X-rays including multiple different energy ranges are split into X-rays of a single energy range and then focused onto the sample, thereby improving the intensity of the X-rays of the single energy range irradiated onto the sample and increasing the contrast of the transmitted X-rays. As a result, the detection sensitivity of foreign matter in the sample in the transmission X-ray inspection device can be improved. Furthermore, by improving the intensity of the X-rays of the single energy range irradiated onto the sample, the time required to inspect each sample for foreign matter can be shortened. Note that, in the present invention, foreign matter in the sample includes foreign matter attached to the surface of the sample and foreign matter contained inside the sample.

[0008] In order to efficiently inspect the sample transported by the transport mechanism, it is desirable that the optical element be a curved spectroscopic element that focuses the X-rays in the one energy range into a line shape.

[0009] The transmitted X-ray detection unit is preferably a line sensor provided corresponding to the linearly focused X-rays. Here, in order to detect all X-rays irradiated onto the sample and improve detection accuracy, it is preferable that the pixel width of the line sensor is approximately the same as the width of the linearly focused X-rays.

[0010] Furthermore, the transmission X-ray inspection apparatus of the present invention is preferably used with a transport mechanism for transporting the sample, and the optical element and the transmission X-ray detection unit are preferably arranged to sandwich the sample transported by the transport mechanism. Here, the longitudinal direction of the linearly focused X-rays and the longitudinal direction of the line sensor are preferably perpendicular to the transport direction of the transport mechanism. This configuration can improve the intensity of X-rays in one energy range irradiated onto the transported sample in a system in which the sample is transported by a transport mechanism. As a result, the integrated dose of the transmission X-ray detection unit can be increased without extending the counting time, and the contrast of the transmitted X-rays can be increased even when the sample is transported at a higher speed than before. As a result, the inspection of samples for foreign matter can be accelerated.

[0011] In order to improve the detection sensitivity of the foreign matter to be detected, it is desirable that the optical element disperse X-rays in a higher energy range than the X-ray absorption edge of the foreign matter to be detected in the sample. Here, the X-ray absorption edge of the foreign matter is a concept that includes, for example, the K absorption edge, L1 absorption edge, L2 absorption edge, or L3 absorption edge, and an X-ray absorption edge is selected depending on the foreign matter, and an optical element is selected accordingly. For example, if the foreign matter is copper, the K absorption edge can be selected.

[0012] In order to improve the intensity of the X-rays irradiated onto the sample, it is desirable to provide two optical elements that split the X-rays into X-rays of the same energy range and focus them onto the sample. With this configuration, the integrated dose of the transmitted X-ray detector can be increased without increasing the counting time, and the contrast of the transmitted X-rays can be increased even when the sample is transported at a higher speed than before. As a result, the precision and speed of sample foreign matter inspection can be improved.

[0013] In order to improve the detection sensitivity for one type of foreign matter or to be able to detect multiple types of foreign matter, it is desirable that the transmission X-ray inspection device of the present invention has multiple types of optical elements, and that the multiple types of optical elements disperse X-rays into X-rays in different energy ranges.

[0014] As a specific embodiment for improving the detection sensitivity of one type of foreign substance, it is desirable to have two types of optical elements, one of which disperses X-rays in an energy range higher than the X-ray absorption edge of the foreign substance to be detected in the sample, and the other of which disperses X-rays in an energy range lower than the X-ray absorption edge.

[0015] Here, it is desirable that the multiple types of optical elements split the X-rays from the single X-ray source into X-rays in different energy ranges. With this configuration, it is not necessary to provide multiple X-ray sources corresponding to the multiple types of optical elements, respectively, and the device can be made smaller.

[0016] In a configuration in which a plurality of types of optical elements are used to separate X-rays into X-rays of mutually different energy ranges, a specific embodiment of the transmission X-ray detection unit is that the transmission X-ray detection unit preferably has a plurality of transmission X-ray detectors for generating a plurality of transmission X-ray images corresponding to the X-rays of the mutually different energy ranges.

[0017] In order to improve the accuracy of detecting foreign matter, it is desirable that the transmission X-ray inspection apparatus of the present invention further includes an image processing unit that processes transmission X-ray images generated using each of the plurality of transmission X-ray detectors, and that the image processing unit perform differential processing using the plurality of transmission X-ray images corresponding to the X-rays in the mutually different energy ranges to detect foreign matter in the sample.

[0018] In order to make it easier for the user to visually recognize detected foreign objects, the transmission X-ray inspection device of the present invention further includes a display control unit that displays the transmission X-ray image on a display, and it is desirable that the display control unit display the foreign objects detected by the image processing unit in color.

[0019] In a specific embodiment for inspecting a first foreign substance and a second foreign substance which are different from each other, the optical element includes a first optical element that disperses the first X-ray into a first X-ray in an energy range lower than the X-ray absorption edge of the first foreign substance, a second optical element that disperses the second X-ray into a second X-ray in an energy range higher than the X-ray absorption edge of the first foreign substance and lower than the X-ray absorption edge of the second foreign substance, and a third optical element that disperses the third X-ray into a third X-ray in an energy range higher than the X-ray absorption edge of the second foreign substance, and it is desirable that the image processing unit detects the first foreign substance and the second foreign substance by performing differential processing using a first transmission X-ray image obtained by irradiating the first X-ray, a second transmission X-ray image obtained by irradiating the second X-ray, and a third transmission X-ray image obtained by irradiating the third X-ray.

[0020] When multiple types of optical elements are arranged, the positional relationship between the X-ray source and the transmission X-ray detection unit differs for each optical element, resulting in different intensities of X-rays irradiated onto the sample. For this reason, it is desirable that the transmission X-ray inspection apparatus of the present invention further include a correction unit that corrects differences in the intensities of X-rays irradiated onto the sample from each of the multiple types of optical elements.

[0021] Furthermore, the transmission X-ray inspection method according to the present invention is characterized in that X-rays emitted from an X-ray source and including a plurality of different energy ranges are dispersed into X-rays of one energy range by an optical element and focused onto a sample, and the transmitted X-rays that have passed through the sample are detected by a transmission X-ray detection unit.

[0022] According to the present invention as described above, it is possible to improve the detection sensitivity of foreign matter in a sample in a transmission X-ray inspection apparatus.

[0023] Fig. 1 is a perspective view schematically showing the overall configuration of a transmission X-ray inspection apparatus according to an embodiment of the present invention; Fig. 2 is a side view schematically showing the overall configuration of the transmission X-ray inspection apparatus in the same embodiment; Fig. 3 is a graph showing the X-ray absorption edge of a foreign object that is a detection target in the same embodiment and the energy of dispersed X-rays; Fig. 4 is a functional block diagram of a signal processing device in the same embodiment; Fig. 5 is a graph showing the X-ray absorption edge of a first foreign object and a second foreign object in a modified embodiment and the energy of dispersed X-rays.

[0024] An embodiment of a transmission X-ray inspection apparatus according to the present invention will be described below with reference to the drawings. Note that, for ease of understanding, all of the drawings shown below are drawn in a schematic manner with appropriate omissions or exaggerations. Identical components are given the same reference numerals, and their descriptions will be omitted where appropriate.

[0025] As shown in FIGS. 1 and 2 , the transmission X-ray inspection apparatus 100 of this embodiment includes an X-ray source 2 that emits primary X-rays, an optical element 3 that disperses the primary X-rays and focuses them onto a sample W, a transmission X-ray detection unit 4 that detects the transmission X-rays that have passed through the sample W, and a signal processing device 5 that processes detection signals from the transmission X-ray detection unit 4.

[0026] The transmission X-ray inspection apparatus 100 of this embodiment also has a transport mechanism 6 that transports the sample W, which is the object of inspection, in a predetermined direction (the left-right direction on the page in FIG. 2 , which is the X direction in this case). The optical element 3 and the transmission X-ray detection unit 4 are arranged to sandwich the sample W transported by the transport mechanism 6 from above and below. With this configuration, the transmission X-ray inspection apparatus 100 of this embodiment can inspect the sample W for foreign matter while transporting the sample W with the transport mechanism 6. The transmission X-ray inspection apparatus 100 can also be an in-line system incorporated into, for example, a film material application apparatus 7 that applies a film material to a substrate. Note that the sample W in this embodiment is, for example, a positive electrode material for a lithium-ion battery, and the foreign matter S to be detected is copper (K-absorption edge energy is 8.98 keV).

[0027] The X-ray source 2 emits primary X-rays (polychromatic X-rays) containing a plurality of different energy ranges (wavelength ranges). Specifically, the X-ray source 2 is an X-ray tube that generates continuous X-rays and characteristic X-rays by colliding electrons generated by heating a filament with a target metal such as tungsten or molybdenum. In this embodiment, the target metal is tungsten.

[0028] The optical element 3 separates the primary X-rays into X-rays in one energy range (one wavelength range) and focuses the X-rays toward the sample W. Here, the one energy range (one wavelength range) is set based on the transmittance of the foreign matter S to be detected, in particular the X-ray absorption edge (here, the K absorption edge of copper).

[0029] Specifically, the optical element 3 is a curved spectroscopic element that disperses (monochromatizes) X-rays into a single energy range and simultaneously focuses them into a line. Here, the longitudinal direction of the X-rays focused into a line by the optical element 3a is perpendicular to the transport direction of the transport mechanism 6 (the Y direction). By using this curved spectroscopic element, the primary X-rays incident with a spread are Bragg-reflected on the curved crystal surface and focused at a predetermined position (here, the upper surface of the sample W), thereby extracting only X-rays in a predetermined energy range. Examples of materials for the curved spectroscopic element include silicon, graphite, and lithium fluoride, which are commonly used as spectroscopic crystals. When the curved spectroscopic element is configured by combining two types of spectroscopic crystals, the wavelength of the X-rays to be dispersed can be changed by changing the curvature of the spectroscopic crystal (the size of the Rowland circle). Furthermore, the wavelength of the X-rays to be dispersed can also be changed by changing the curvature of the spectroscopic crystal (the size of the Rowland circle) and / or the material of the spectroscopic crystal. The optical element 3 of this embodiment is designed to detect the L of fluorescent X-rays of tungsten. β (high energy; 9.67-9.96 keV) and L α (low energy; 8.40 keV) and the resulting light are dispersed and collected.

[0030] 1 and 2, this embodiment has multiple types (two types in this example) of optical elements 3a and 3b that split X-rays into X-rays of different energy ranges. One of the two types, 3a, splits X-rays into X-rays in a high-energy range while focusing them on the sample W. The other of the two types, 3b, splits X-rays into X-rays in a low-energy range while focusing them on the sample W.

[0031] 3, the X-rays dispersed by one optical element 3a are X-rays in a higher energy range than the X-ray absorption edge of the foreign substance S to be detected in the sample W. The X-rays dispersed by the other optical element 3b are X-rays in a lower energy range than the X-ray absorption edge of the foreign substance S to be detected in the sample W.

[0032] The transmission X-ray detection unit 4 detects the transmission X-rays transmitted through the sample W, and as shown in Figures 1 and 2, is configured using transmission X-ray detectors 4a and 4b, each consisting of a line sensor, provided on the underside of the sample W. These transmission X-ray detectors 4a and 4b are provided corresponding to the X-rays focused in a line shape. In other words, the longitudinal direction of the transmission X-ray detectors 4a and 4b is a direction (Y direction) perpendicular to the transport direction of the transport mechanism 6. Furthermore, the pixel width of the transmission X-ray detectors 4a and 4b is approximately the same as the width of the X-rays focused in a line shape.

[0033] The transmission X-ray detection unit 4 of this embodiment has multiple (here, two) transmission X-ray detectors 4a, 4b for generating multiple transmission X-ray images corresponding to X-rays in different energy ranges. One of the transmission X-ray detectors, 4a, is a line sensor provided corresponding to one of the optical elements 3a and detects transmission X-rays from a sample W irradiated with X-rays in the high-energy range. The other transmission X-ray detector, 4b, is a line sensor provided corresponding to the other optical element 3b and detects transmission X-rays from a sample W irradiated with X-rays in the low-energy range. Each line sensor has a linear scintillator and an X-ray filter provided in front of the scintillator on the X-ray entrance side. The X-ray filter transmits the transmission X-rays to be detected while blocking other disturbing X-rays. The line sensor may also be configured using a semiconductor radiation detector (SDD) or a photomultiplier tube.

[0034] The signal processing device 5 processes the detection signal from the transmission X-ray detection unit 4 to generate a transmission X-ray image and detect foreign matter from the transmission X-ray image. Specifically, the signal processing device is a computer having a CPU, memory, an input / output interface, a display 50, input means, etc., and as shown in Fig. 4, has the functions of an image generation unit 5a, an image processing unit 5b, a foreign matter detection unit 5c, a display control unit 5d, etc.

[0035] The image generation unit 5a acquires detection signals from the multiple transmission X-ray detectors 4a, 4b and generates multiple transmission X-ray images. In this embodiment, a transmission X-ray image in a high-energy range is generated using the detection signal from one transmission X-ray detector 4a, and a transmission X-ray image in a low-energy range is generated using the detection signal from the other transmission X-ray detector 4b. The transmission X-ray images generated by the image generation unit 5a are transmitted to the image processing unit 5b and also to the display control unit 5d.

[0036] The image processing unit 5b performs differential processing using the high-energy transmission X-ray image and the low-energy transmission X-ray image generated by the image generation unit 5a to detect foreign matter in the sample W. The image processing unit 5b generates a differential image between the high-energy transmission X-ray image and the low-energy transmission X-ray image to increase the contrast of the transmission X-ray image and make it easier to extract foreign matter S. The differential image generated by the image processing unit 5b is transmitted to the foreign matter detection unit 5c and also to the display control unit 5d.

[0037] The foreign object detection unit 5c detects foreign objects S from the difference image generated by the difference processing of the image processing unit 5b. This foreign object detection unit 5c, for example, calculates the foreign object size from the difference image and detects a foreign object when the foreign object size is, for example, 20 μm or more in area equivalent diameter. Foreign object information indicating the foreign object detected by this foreign object detection unit 5c is transmitted to the display control unit 5d. Note that the foreign object information is image data in which the foreign object is detected, and this image data is also stored in the memory of the signal processing device 5. The foreign object detection unit 5c can also transmit the image data together with error information indicating that a foreign object has been detected to a server (host control device) in the control room, etc.

[0038] The display control unit 5d displays the foreign object S detected by the foreign object detection unit 5c on the display 50. Specifically, the display control unit 5d displays the detected foreign object S superimposed on the difference image generated by the image processing unit 5b on the display 50. Here, the display control unit 5d can display the detected foreign object in a manner that is easy for the user to see, such as by coloring the detected foreign object.

[0039] Additionally, the display control unit 5d can display the X-ray transmission images in each energy range generated by the image generation unit 5a or the difference images generated by the image processing unit 5b on the display 50. Furthermore, the display control unit 5d can also display the X-ray transmission images in each energy range generated by the image generation unit 5a and the detected foreign matter superimposed on each other on the display 50.

[0040] <Effects of this embodiment> According to the transmission X-ray inspection apparatus 100 of this embodiment configured as described above, X-rays including a plurality of different energy ranges are dispersed into X-rays of one energy range and then focused onto the sample W, so that the intensity of the X-rays of one energy range irradiated onto the sample W can be improved and the contrast of the transmitted X-rays can be increased. As a result, the detection sensitivity of the transmission X-ray inspection apparatus 100 for foreign matter S in the sample W can be improved. Furthermore, by improving the intensity of the X-rays of one energy range irradiated onto the sample W, the time required for foreign matter inspection for each sample W can be shortened.

[0041] Furthermore, in a system in which a sample W is transported by a transport mechanism 66, the intensity of X-rays in one energy range irradiated onto the transported sample W can be improved. As a result, the integrated dose of the transmitted X-ray detection unit 4 can be increased without increasing the counting time, and the contrast of the transmitted X-rays can be increased even when the sample W is transported at a higher speed than before. As a result, the speed of foreign matter inspection of the sample W can be increased.

[0042] Other Embodiments For example, while the above embodiment focuses on one type of foreign matter as a detection target, two or more types of foreign matter may also be detected. Specifically, when inspecting for first and second foreign matters of different types, the optical element 3 includes a first optical element that disperses the first X-rays (see FIG. 5 ) in an energy range lower than the X-ray absorption edge of the first foreign matter, a second optical element that disperses the second X-rays (see FIG. 5 ) in an energy range higher than the X-ray absorption edge of the first foreign matter but lower than the X-ray absorption edge of the second foreign matter, and a third optical element that disperses the third X-rays (see FIG. 5 ) in an energy range higher than the X-ray absorption edge of the second foreign matter. Note that the first to third optical elements are curved dispersing elements, as in the above embodiment. Furthermore, the transmission X-ray detection unit 4 includes three transmission X-ray detectors corresponding to these three optical elements.

[0043] The image processing unit 5b then performs differential processing using the first transmission X-ray image obtained by irradiating the first X-ray, the second transmission X-ray image obtained by irradiating the second X-ray, and the third transmission X-ray image obtained by irradiating the third X-ray to detect the first and second foreign objects. Specifically, the first foreign object is detected by differential processing between the second and first X-ray images, and the second foreign object is detected by differential processing between the third and second X-ray images. The display control unit 5d may display the detected first and second foreign objects separately, or may color-code the first and second foreign objects in different colors within a single image. Note that the first foreign object may also be detected by differential processing between the third X-ray image and the first X-ray image.

[0044] The signal processing device 5 may further include a correction unit that corrects differences in the intensities of X-rays irradiated onto the sample W from each of the multiple optical elements 3. This correction unit may correct parameters used when generating a transmission X-ray image in the image generation unit 5a, based on the optical arrangement of the X-ray source 2, the transmission X-ray detection unit 4, and the multiple optical elements 3. The correction unit may also correct the multiple transmission X-ray images, based on the optical arrangement of the X-ray source 2, the transmission X-ray detection unit 4, and the multiple optical elements 3.

[0045] Furthermore, the signal processing device 5 may further include a sensitivity correction unit that corrects the detection sensitivities of the plurality of transmission X-ray detectors 4a, 4b so as to match each other.

[0046] Furthermore, in the above embodiment, X-rays from one X-ray source 2 are split into X-rays in different energy ranges by a plurality of optical elements 3, but a plurality of X-ray sources 2 may be provided. For example, an X-ray source 2 may be provided corresponding to each of the plurality of optical elements 3.

[0047] Although the above embodiment has been described as including a plurality of optical elements and a plurality of transmission X-ray detectors, a configuration having one optical element and one transmission X-ray detector may be used. In this case, the optical element may disperse and collect X-rays having an energy higher than the K-absorption edge of the foreign matter.

[0048] Furthermore, the configuration shown in FIG. 6 may be used as a configuration for splitting X-rays from the X-ray source 2 into X-rays in a single energy range and irradiating the sample W. In the configuration shown in FIG. 6, two identical optical elements 3 are arranged facing each other. Here, the two optical elements 3 are curved spectroscopic elements that split (monochromatize) X-rays into X-rays in the same energy range and simultaneously focus the X-rays into a line. The two optical elements 3 are arranged so that the X-rays focused into a line by each optical element 3 coincide with each other on the sample W. A first collimator 81 is provided between the X-ray source and the optical element 3 to remove X-rays that do not enter the optical element 3, and a second collimator 82 is provided between the optical element 3 and the sample W to remove X-rays other than those in the desired energy range. A third collimator 83 may be provided between the second collimator and the sample W to remove unnecessary X-rays, if necessary. The optical system configuration shown in FIG. 6 can improve the intensity of the X-rays irradiated onto the sample W. As a result, the integrated dose of the transmitted X-ray detector can be increased without increasing the counting time, and the contrast of the transmitted X-rays can be increased even when the sample is transported at a higher speed than before, thereby enabling higher precision and speed in the inspection of samples for foreign matter.

[0049] Furthermore, in addition to the configuration of the above embodiment, a configuration may be provided in which a notification unit notifies the user by issuing an error or the like when the foreign object detection unit detects a foreign object.

[0050] In addition, in the above embodiment, the sample W transported by the transport mechanism 6 is inspected for foreign matter, but the apparatus may be a stand-alone type in which the sample is placed on a fixed inspection table and the foreign matter inspection is performed.

[0051] In addition, various modifications and combinations of the embodiments may be made as long as they do not go against the spirit of the present invention.

[0052] According to the present invention, it is possible to improve the detection sensitivity of foreign matter in a sample in a transmission X-ray inspection apparatus.

[0053] 100: Transmission X-ray inspection apparatus W: Sample 2: X-ray source 3 (3a, 3b): Optical element 4: Transmission X-ray detection unit 4a, 4b: Transmission X-ray detector 5: Signal processing device 51: Image processing unit 52: Display control unit

Claims

1. An X-ray source that emits X-rays including a plurality of different energy regions, an optical element that disperses the X-rays into X-rays of one energy region and condenses them toward a sample, and a transmission X-ray detector that detects the transmitted X-rays that have passed through the sample. A transmission X-ray inspection apparatus.

2. The transmission X-ray inspection apparatus according to claim 1, wherein the optical element is a curved spectroscopic element that condenses the X-rays of the one energy region in a line shape.

3. The transmission X-ray inspection apparatus according to claim 2, wherein the transmission X-ray detector is a line sensor provided corresponding to the X-rays condensed in the line shape.

4. It is used together with a transport mechanism for transporting the sample, The transmission X-ray inspection apparatus according to any one of claims 1 to 3, wherein the optical element and the transmission X-ray detector are arranged with the sample transported by the transport mechanism therebetween.

5. The transmission X-ray inspection apparatus according to any one of claims 1 to 3, wherein the optical element disperses the X-rays into an energy region higher than the X-ray absorption edge of a foreign object to be detected in the sample.

6. The transmission X-ray inspection apparatus according to any one of claims 1 to 3, further comprising two optical elements that disperse the X-rays into X-rays of the same energy region and condense them toward the sample.

7. Having a plurality of types of the optical elements, The transmission X-ray inspection apparatus according to any one of claims 1 to 3, wherein the plurality of types of optical elements disperse the X-rays into X-rays of different energy regions.

8. Having two types of the optical elements, One of the two types of optical elements disperses the X-rays into an energy region higher than the X-ray absorption edge of a foreign object to be detected in the sample, The transmission X-ray inspection apparatus according to claim 7, wherein the other of the two types of optical elements disperses the X-rays into an energy region lower than the X-ray absorption edge.

9. The transmission X-ray inspection apparatus according to claim 7, wherein the plurality of types of optical elements disperse the X-rays from one X-ray source into X-rays of different energy regions.

10. The transmission X-ray inspection apparatus according to claim 7, wherein the transmission X-ray detector has a plurality of transmission X-ray detectors for generating a plurality of transmission X-ray images corresponding to the X-rays of the different energy regions respectively.

11. Further comprising an image processing unit that processes the transmission X-ray images generated using each of the plurality of transmission X-ray detectors, The transmission X-ray inspection apparatus according to claim 10, wherein the image processing unit performs differential processing using a plurality of transmission X-ray images corresponding to X-rays in the mutually different energy regions, and detects foreign matter in the sample.

12. The transmission X-ray inspection apparatus further comprising a display control unit that causes the transmission X-ray image to be displayed on a display, The display control unit causes the foreign matter detected by the image processing unit to be displayed with a color, the transmission X-ray inspection apparatus according to claim 11.

13. It inspects first foreign matter and second foreign matter of different types from each other, The optical element includes a first optical element that disperses into first X-rays in an energy region lower than the X-ray absorption edge of the first foreign matter, an energy region higher than the X-ray absorption edge of the first foreign matter, and also lower than the X-ray absorption edge of the second foreign matter. a second optical element that disperses into second X-rays in an energy region, and a third optical element that disperses into third X-rays in an energy region higher than the X-ray absorption edge of the second foreign matter, The image processing unit performs differential processing using a first transmission X-ray image obtained by irradiating the first X-ray, a second transmission X-ray image obtained by irradiating the second X-ray, and a third transmission X-ray image obtained by irradiating the third X-ray, and the first foreign matter and the second foreign matter are detected, the transmission X-ray inspection apparatus according to claim 9.

14. The transmission X-ray inspection apparatus according to claim 7, further comprising a correction unit that corrects differences in X-ray intensities irradiated on the sample from each of the plurality of types of optical elements.

15. X-rays including a plurality of mutually different energy regions emitted from an X-ray source are dispersed by an optical element into X-rays in one energy region and condensed toward a sample, A transmission X-ray inspection method, wherein the transmission X-rays transmitted through the sample are detected by a transmission X-ray detector.