JP4608679B2 - Manufacturing method of phase type diffraction grating and amplitude type diffraction grating used in X-ray Talbot interferometer - Google Patents

Description

  The present invention relates to a method for manufacturing a phase type diffraction grating and an amplitude type diffraction grating used in an X-ray Talbot interferometer.

  X-ray fluoroscopy devices are widely used for medical image diagnostic techniques, for example. However, because of the principle of forming an image contrast by the magnitude of X-ray absorption by a subject, blood, blood vessel walls and surrounding soft tissues There is a problem that X-ray absorption coefficients are almost equal and it is difficult to obtain a sufficient contrast. A certain amount of contrast can be obtained if imaging is performed for a long time, but there is a problem that the dose of X-rays increases and the burden on the patient increases. In addition, for example, a method of injecting a contrast material such as iodine in order to enhance the contrast of blood vessels in the image is conceivable, but this also increases the burden on the patient and increases the examination cost.

  On the other hand, there is also known a phase contrast method that grasps X-rays as a wave and uses a difference in the speed at which the wave is transmitted through a subject for contrast formation, such as a method using an X-ray interferometer. In other words, this is a method for detecting a phase shift of X-rays due to transmission through a subject. This phase contrast method has an advantage that sensitivity can be improved by about 1000 times compared with a method that relies on absorption of X-rays, and the X-ray irradiation dose can be reduced to, for example, 1/100 to 1/1000. In addition, from the viewpoint of improving the spatial resolution, it can be said that the above improvement in sensitivity brings a very favorable effect.

The inventor of the present application has found the usefulness of performing image diagnosis using an X-ray interferometer from an early stage. For example, in Patent Document 1, a Mach-Zehnder type X-ray interferometer is configured, and this X-ray beam path It is proposed that an image showing a phase shift distribution by a subject can be obtained by arranging a region to be inspected and analyzing a moire image of the obtained X-ray interferogram. According to such a configuration, it is assumed that blood vessels and blood distribution can be easily visualized by using X-rays without contrast or by injecting a substance not containing heavy elements.
JP 2001-29340 A

  Here, in recent years, as an environment capable of obtaining coherent and high-intensity X-rays, such as the use of large-scale facilities (for example, SPring 8 in Japan) that can obtain high-intensity X-rays, spatial coherence is achieved. It has been studied to apply a Talbot interferometer configured to detect the gradient of an incident wavefront using a light source and two diffraction gratings in the X-ray field.

  Although this Talbot interferometer can be realized with a simple optical system, various advantages are pointed out. However, the two diffraction gratings that allow this X-ray Talbot interferometer to function well can be manufactured stably.・ As for the supply method, special technology in processing is required, and the actual situation is not established yet.

Means and effects for solving the problems

  The problems to be solved by the present invention are as described above. Next, means for solving the problems and the effects thereof will be described.

According to the viewpoint of the present invention, the following manufacturing method of a phase type diffraction grating and an amplitude type diffraction grating used for an X-ray Talbot interferometer is provided. Both diffraction gratings have a configuration in which X-ray absorption parts made of metal with a width of 2 μm or more and 10 μm or less are arranged at equal intervals of 2 μm or more and 10 μm or less. Same for the grid. The thickness of the phase type diffraction grating is configured to be 1 μm or more and 5 μm or less, and the thickness of the amplitude type diffraction grating is configured to be 25 μm or more and 100 μm or less. The amplitude type diffraction grating is manufactured by forming a deep groove in a resin by X-ray lithography (LIGA method) using an X-ray mask, and forming the X-ray absorption portion by electroforming in the formed groove.

As a result, since the width and interval (grating pattern) of the X-ray absorption part are the same in the phase type diffraction grating and the amplitude type diffraction grating, in the X-ray Talbot interferometer, an accurate moire immediately after the amplitude type diffraction grating. Stripes can be obtained reliably. Further, in the phase type diffraction grating, the phase shift amount when passing through it can be set to a thickness sufficient to make π / 2 (the phase shift amount for obtaining the highest contrast moire fringe), and the amplitude In the type diffraction grating, the thickness can be sufficient to realize a low transmission intensity ratio with good visibility of moire fringes. Therefore, clear moire fringes can be obtained, and an X-ray Talbot interferometer with high reliability and accuracy can be realized. Further, in an amplitude type diffraction grating having a large thickness (requiring processing with a large aspect ratio), processing with sufficient accuracy can be performed using a so-called LIGA process.

Further , according to the aspect of the present invention, there are provided the following method for manufacturing a phase type diffraction grating and an amplitude type diffraction grating used for an X-ray Talbot interferometer. Both diffraction gratings have a configuration in which X-ray absorption parts made of metal with a width of 2 μm or more and 10 μm or less are arranged at equal intervals of 2 μm or more and 10 μm or less. Same for the grid. The thickness of the phase type diffraction grating is configured to be 1 μm or more and 5 μm or less, and the thickness of the amplitude type diffraction grating is configured to be 25 μm or more and 100 μm or less. Amplitude-type diffraction grating, to form a resin layer on the surface of the silicon layer which has been subjected to silicon oxide film, patterning is performed with respect to the resin layer by using a light science lithography mask, selectively the resin layer and the silicon oxide film To remove. A groove is formed in the silicon layer by performing ICP plasma etching on the surface of the silicon layer exposed selectively. The X-ray absorption part is formed in the formed groove by electroforming.

As a result, the width and interval (grating pattern) of the X-ray absorption part are the same for the phase type diffraction grating and the amplitude type diffraction grating, so that in the X-ray Talbot interferometer, an accurate moiré pattern immediately after the amplitude type diffraction grating. Stripes can be obtained reliably. Further, in the phase type diffraction grating, the phase shift amount when passing through it can be set to a thickness sufficient to make π / 2 (the phase shift amount for obtaining the highest contrast moire fringe), and the amplitude In the type diffraction grating, the thickness can be sufficient to realize a low transmission intensity ratio with good visibility of moire fringes. Therefore, clear moire fringes can be obtained, and an X-ray Talbot interferometer with high reliability and accuracy can be realized. Further, (requiring large processing aspect ratio) of thickness greater in the amplitude type diffraction grating, Ru can be performed processing of sufficient accuracy by ICP plasma etching method.

  In addition, in the above-mentioned amplitude type diffraction grating, a mold having the projecting portion as an X-ray absorption portion formed by the above manufacturing method is manufactured, and a groove forming body is formed using this mold. The amplitude type diffraction grating may be obtained by forming the X-ray absorbing portion in the groove formed in the groove forming body by electroforming.

  In this case, since a large number of groove forming bodies having the same shape can be easily manufactured, it suffices to form X-ray absorbers in the grooves of the groove forming body, which is suitable for cost reduction due to mass production.

In the amplitude-type diffraction grating, the above-described manufacturing method may be applied to produce a plurality of divided grating blocks, and the amplitude-type diffraction grating may be obtained by joining them in the thickness direction.

This makes it possible to facilitate the processing of the amplitude type diffraction grating. That is, in the case where a thick one such as an amplitude type diffraction grating is formed as a single body, a deep groove for forming the X-ray absorption portion must be formed, and the width and interval of the X-ray absorption portion are constant. It becomes difficult to form due to processing problems. In this regard, if a method is employed in which a plurality of divided grid blocks each having a small thickness are manufactured and joined together as described above, such accuracy problems are reduced, and the widths and intervals are uniform in the thickness direction. It becomes easy to manufacture a type diffraction grating.

  In the method for manufacturing the phase type diffraction grating and the amplitude type diffraction grating, it is preferable that the X-ray absorption part is made of one or a combination of two or more selected from platinum, gold, silver, and platinum. .

  As a result, the X-ray absorption capability of the X-ray absorption unit is excellent, so that a good Talbot interference image can be obtained even with a diffraction grating having a small thickness, making the diffraction grating easier to manufacture, and making the Talbot interferometer more compact. Can contribute.

  Next, embodiments of the invention will be described. FIG. 1 is a conceptual diagram of an X-ray Talbot interferometer using a diffraction grating according to the manufacturing method of the present invention. 2A is a diagram showing an example of a Talbot interference image obtained by an X-ray Talbot interferometer, FIG. 2B is a diagram showing a differential phase image obtained by a fringe scanning method, and FIG. 2C is an X-ray. It is a figure which shows the example of phase type CT.

  First, an optical system of an X-ray Talbot interferometer using a diffraction grating manufactured by the method of the present invention will be described with reference to FIG. In this X-ray Talbot interferometer, the first diffraction grating (phase-type diffraction grating) 11 and the second diffraction grating (amplitude-type diffraction grating) 12 are arranged in parallel at a specific distance to be observed. The sample 10 is placed in front of the phase type diffraction grating 11. Each of the two diffraction gratings 11 and 12 has a configuration in which X-ray absorbing portions 111 and 121 that are elongated in the y direction that absorb X-rays are periodically arranged in the x direction.

  Here, when the period of the diffraction gratings 11 and 12 is sufficiently larger than the wavelength, the light after passing through the phase-type diffraction grating 11 has a very small diffraction angle, so that a large number of diffracted lights are generated. Overlapping and interfering. Then, the same pattern as that immediately after the transmission through the phase-type diffraction grating 11, that is, the self-image appears as a result of interference (Talbot effect) at a position separated by a distance that satisfies the condition that the phases of the diffracted lights are aligned.

  Next, focusing on the self-image when the sample 10 is placed in front of the phase-type diffraction grating 11, each interfering diffracted light passes through a slightly different optical path inside the sample 10, so that The appearance of interference fringes changes depending on the phase difference. Therefore, a so-called moire fringe image (Talbot interference image) G can be obtained by superimposing the amplitude diffraction grating 12 on the position of the deformed self-image, and in this image G, the differential phase appears as contour lines. (Refer to FIG. 2A). 2A is a Talbot interference image when a plastic sphere having a diameter of 1.2 mm is used as the sample 10. FIG.

  It is difficult to obtain the differential phase quantitatively only by observing the Talbot interference image G. However, by analyzing the change of the interference fringe when the fringe phase is artificially changed, the differential phase is obtained. The phase can be determined (stripe scanning method). For example, by acquiring and analyzing a plurality of Talbot interference images G while changing the phase of moire fringes by shifting the relative positional relationship between the two diffraction gratings 11 and 12 in FIG. A quantitative differential phase image as shown in b) can be obtained. If this image is simply integrated, the phase image itself can be obtained.

  Further, a differential phase image as shown in FIG. 2B is acquired from a large number of projection directions with respect to the sample 10, and this is integrated to obtain a phase image, and a phase image from a large number of projection directions is synthesized. Thus, as shown in FIG. 2C, phase X-ray CT (computer tomography) can be performed. FIG. 2C shows a cross section obtained by virtually cutting the plastic sphere as the sample 10 by 1/8 on the computer, and the internal bubbles 10a that are thought to have been formed when the plastic sphere as the sample 10 was formed. The situation can be clearly observed.

  The X-ray Talbot interferometer is a simple optical system in which only two diffraction gratings 11 and 12 are arranged after the sample 10 as shown in FIG. 1 and does not use delicate optical elements such as crystals. It has the feature that precise optical element adjustment and high stability are not so necessary. In addition, since the intensity is detected as moire fringes, it is advantageous in that a detector with high spatial resolution is not necessarily required. In addition, the Talbot interferometer requires a small light source in principle, but not so much monochromaticity, and divergent light such as spherical waves can be used. The X-ray source can be used, and it is expected that it will contribute to the miniaturization of the apparatus and open the way to practical use in hospitals.

  In addition, although it is an X-ray Talbot interferometer whose usefulness is pointed out as described above, since the X-ray is generally very small in absorption by a substance and the phase change is not so large, the diffraction gratings 11 and 12 are manufacture than that of the Talbot interferometer of the visible light region is difficult. Of course, in order for the Talbot interferometer to function, it is necessary to make the period of each X-ray absorber 111 or 121 of the diffraction grating 11 or 12 smaller than the X-ray coherence distance, and it is 10 μm or less, preferably 5 μm. It needs to be about.

  The self-image due to the so-called fractional Talbot effect has the property that the highest contrast is obtained when the phase shift amount of the phase-type diffraction grating 11 is π / 2. Then, when the inventors of the present application estimated the thickness of the phase type diffraction grating 11 necessary for realizing the phase shift amount of π / 2, the diffraction grating 11 was obtained when the wavelength was 0.7 to 1.1 mm. In the case where gold having a high X-ray absorption capability was used as the material for the X-ray absorption portion 111, the phase diffraction grating 11 had a thickness of 1 μm to 10 μm.

  On the other hand, with respect to the amplitude type diffraction grating 12, it is important to reduce the intensity transmittance of the amplitude type diffraction grating 12 from the viewpoint of improving the visibility of the moire fringes obtained by the Talbot interferometer. % is ideal as long to obtain an X-ray absorption of a degree that can be achieved. In this regard, for example, when the inventors of the present application similarly calculated the thickness of the amplitude type diffraction grating 12 necessary for realizing an intensity transmittance of 1%, even if gold was used as a material, the wavelength was 0.7 mm. The result that the thickness of 10 micrometers-100 micrometers was needed in the case of -1.1 mm was obtained.

  Accordingly, in realizing an X-ray Talbot interferometer, can such two diffraction gratings 11 and 12 be manufactured, in particular, an amplitude type diffraction grating 12 that requires a very large aspect ratio (for example, 5 or more)? No is an important key.

  In order to solve the above problems, the inventor of the present application has made extensive studies and has proposed a method of manufacturing the phase type diffraction grating 11 and the amplitude type diffraction grating 12 as described below. Hereinafter, each will be described in detail.

  First, a specific configuration of the two diffraction gratings 11 and 12 will be described with reference to FIG. The phase type diffraction grating 11 shown on the upper side of FIG. 3 is integrally formed on one surface of the glass substrate B having a thickness of about 150 μm, for example. The phase type diffraction grating 11 is composed of a long and narrow X-ray absorbing portion 111 provided on the glass substrate B in a line at equal intervals. Each of the X-ray absorption parts 111 is made of gold having excellent X-ray absorption ability, and the thickness t1 (corresponding to the thickness of the phase-type diffraction grating 11) protruding from the glass substrate B is any X-ray absorption. The portions 111 are also equal to each other and are 1 μm or more and 5 μm or less. The space between the X-ray absorber 111 and the X-ray absorber 111 is a simple space.

  The widths w1 of the plurality of X-ray absorbers 111 are configured to be equal to each other, and the widths w1 are 2 μm or more and 10 μm or less. Further, the gap g1 between the X-ray absorbing portions 111 is also set to 2 μm or more and 10 μm or less.

  On the other hand, the amplitude type diffraction grating 12 shown in the lower side of FIG. 3 corresponds to the phase type diffraction grating 11 extended in the thickness direction (X-ray optical axis direction). Specifically, each X-ray absorption part 121 of the amplitude type diffraction grating 12 has a shape that is narrow and long and has a large thickness, and a large number of them are arranged in the width direction at equal intervals. Each of the X-ray absorption parts 121 is made of gold having excellent X-ray absorption capability as in the phase type diffraction grating 11, and the thickness t2 (corresponding to the thickness of the amplitude type diffraction grating 12) is 25 μm or more. 100 μm or less. A resin member 122 is sandwiched between the X-ray absorber 121 and the X-ray absorber 121. In other words, the X-ray absorbing portion 121 and the resin member 122 are alternately stacked and joined. Note that a holding member 123 made of silicon oxide may be interposed between the adjacent X-ray absorption parts 121 and 121 instead of the resin member 122.

  The plurality of X-ray absorbers 121 are configured to have the same width w2, and the width is 2 μm or more and 10 μm or less. Further, the gap g2 between the X-ray absorption parts 121 is also set to 2 μm or more and 10 μm or less. Furthermore, the X-ray absorption parts 111 and 121 of both diffraction gratings 11 and 12 have the same width and interval between the diffraction gratings (w1 = w2, g1 = g2).

  With the above configuration, it is ensured that the phase type diffraction grating 11 and the amplitude type diffraction grating 12 are the same, and the position immediately after the amplitude type diffraction grating 12 in the X-ray Talbot interferometer of FIG. Thus, an accurate moire fringe Talbot interference image G can be obtained with certainty. Furthermore, the phase type diffraction grating 11 can have a thickness sufficient to set the phase shift amount when X-rays pass through it to π / 2. Further, the amplitude type diffraction grating 12 can have a thickness sufficient to realize a low transmission intensity rate with good visibility of moire fringes. Therefore, clear moire fringes can be obtained, and an X-ray Talbot interferometer with high reliability and accuracy can be realized.

[Method of manufacturing phase-type diffraction grating]
Next, a method for manufacturing the phase type diffraction grating 11 will be described with reference to FIG. First, as shown in FIG. 4 (p1), a photosensitive resin (for example, polyvinyl alcohol resin) 31 is applied to one surface of the glass substrate B, and an optical lithography mask (optical) for pattern exposure of the photosensitive resin 31 is applied. Mask) 34 is prepared. As this optical mask 34, for example, an appropriate glass substrate 32 having a pattern 33 formed in a thin film shape on one side surface of chromium or chromium oxide can be used.

  Next, as shown in FIG. 4 (p2), ultraviolet rays are used as a light source, and the pattern 33 of the optical mask 34 is accurately transferred to the photosensitive resin 31 on the glass substrate B. Then, the exposed portion of the photosensitive resin 31 is selectively removed in the developing step (p3), and the X-ray absorbing portion 111 is formed in the portion where the photosensitive resin 31 is removed by the gold plating step (p4). . Further, as shown in FIG. 4 (p5), the above-described photosensitive resin 31 is removed. Through the above steps, it is possible to produce a phase-type diffraction grating 11.

[Amplitude diffraction grating manufacturing method 1]
Next, a manufacturing method of the amplitude type diffraction grating 12 will be described with reference to FIG. This method combines X-ray lithography with electroforming and molding, and is sometimes referred to as “LIGA” after the German initials (LIthographie, Galvanoformung, Abformung) of each process. It is known as a suitable method for forming a precise shape having a large aspect ratio such as a groove having a depth of several hundred μm by pattern transfer of an X-ray mask to a photosensitive resin having a large thickness. .

  More specifically, first, as shown in FIG. 5 (p1), a substrate 35 serving as a base for manufacturing a diffraction grating is prepared, and an X-ray photosensitive resin (for example, polymethyl methacrylate resin) 36 is provided on one surface thereof. a, for example, it is applied using a roll coating or spin coating or the like.

  On the other hand, which is prepared an X-ray mask 47 for pattern exposure. This X-ray mask 47 is formed by forming a gold pattern 49 on one surface of a suitable substrate 48 and further covering it with a protective film 50 made of synthetic resin or the like. The gold pattern 49 is patterned using the optical mask 34 used in the method of manufacturing the phase type diffraction grating 11 described with reference to FIG. 4 as it is so as to be the same pattern as the grating pattern of the phase type diffraction grating 11 described above. It is preferable.

  Next, as shown in FIG. 5 (p <b> 2), X-rays are used as a light source, and the gold pattern 49 of the X-ray mask 47 is accurately transferred to the X-ray photosensitive resin 36 on the substrate 35. The portion exposed to X-rays dissolves in the developer because the polymer chain is broken and the molecular weight is reduced, while the gold pattern 49 remains as it is. As a result, the X-ray photosensitive resin 36 other than the portion corresponding to the gold pattern 49 can be selectively removed in the developing step (p3), and the groove 51 can be formed. In other words, the resin member 122 described in the lower diagram of FIG. 3 is formed on the substrate 35. Thereafter, in FIG. 5 (p4), the X-ray absorption part 121 is formed by gold plating between the resin member 122 and the resin member 122 (electroforming), and the substrate 35 is removed in (p5). Through the above steps, it is possible to produce an amplitude type diffraction grating 12.

  As described above, in the phase type diffraction grating 11 which may be small in thickness (a processing with an aspect ratio of, for example, 1 or less), a manufacturing method with a low cost and man-hour as shown in FIG. 4 is adopted. While the manufacturing cost is reduced, the so-called LIGA process is used to sufficiently process such a large aspect ratio in the amplitude type diffraction grating 12 having a large thickness (processing requiring an aspect ratio of, for example, 5 or more). Can be performed with high accuracy. Further, since the X-ray mask 47 of the amplitude type diffraction grating 12 is formed using the optical mask 34 used in the manufacturing process of the phase type diffraction grating 11, the identity of the grating patterns of both diffraction gratings 11 and 12 is good. Can be secured.

[Amplitude diffraction grating manufacturing method 2]
The amplitude type diffraction grating 12 can be manufactured by the method shown in FIG. 6 in addition to the above method. The method of FIG. 6 will be described. First, as shown in FIG. 6 (p1), a plate-like silicon layer 38 having an appropriate thickness (for example, 50 μm) is prepared, and a silicon oxide film (SiO 2) is formed on one surface thereof. ₂ film) 39 and a photosensitive resin layer 40 such as polyvinyl alcohol resin is formed on the silicon oxide film 39. On the other hand, a substrate 37 is provided on the other surface of the silicon layer 38. The substrate 37 may be formed, for example, by depositing titanium on the surface on the other side of the silicon layer 38, but is not limited thereto, and may be formed of silicon, for example.

  On the other hand, an optical mask 34 for pattern exposure of the photosensitive resin layer 40 is prepared. This means that the optical mask 34 used in the manufacturing process of the phase type diffraction grating 11 described in FIG. 4 is used as it is.

  Next, as shown in FIG. 6 (p <b> 2), ultraviolet rays are used as a light source, and the pattern 33 of the optical mask 34 is accurately transferred to the photosensitive resin layer 40 on the silicon oxide film 39. In the developing step (p3), the photosensitive resin layer 40 and the silicon oxide film 39 other than the pattern 33 are selectively removed. Further, as shown in FIG. 6 (p4), the exposed silicon film 38 is now inductively coupled (ICP) by using the selectively left photosensitive resin layer 40 and silicon oxide film 39 as a mask. Selective etching is performed by plasma etching. In this way, the holding member 123 shown in the lower diagram of FIG. 3 can be formed. Thereafter, in the process of FIG. 6 (p5), the X-ray absorbing portion 121 is formed by gold plating between the holding member 123 and the holding member 123 (electroforming method), and the substrate 37 is removed. Thus, it is possible to produce an amplitude type diffraction grating 12.

  As described above, the amplitude type diffraction grating 12 having a large thickness (requiring processing with a large aspect ratio) can be processed with sufficient accuracy by using the ICP plasma etching method. Also in the manufacturing method of FIG. 6, a mask (silicon oxide film 39 and photosensitive resin layer 40 in the case of ICP plasma etching of the amplitude type diffraction grating 12 based on the optical mask 34 used in the manufacturing process of the phase type diffraction grating 11. Therefore, the identity of the grating patterns of both diffraction gratings 11 and 12 can be ensured satisfactorily.

[Method of manufacturing amplitude type diffraction grating by split type]
In addition, by applying the manufacturing method 1 (FIG. 5) or the manufacturing method 2 (FIG. 6), a plurality of divided bodies (divided grating blocks) 12s are manufactured instead of the amplitude type diffraction grating itself, and the plurality of divided gratings are manufactured. By joining the blocks 12s in the thickness direction as shown in FIG. 7 while aligning the blocks, the amplitude type diffraction grating 12 having a large thickness direction as shown in the lower side of FIG. 3 can be easily manufactured. This method is suitable for the case where the amplitude type diffraction grating 12 in which the thickness t2 of the X-ray absorber 121 is extremely large with respect to the width w2 or the interval g2 is formed. That is, when such a large thickness t2 is formed as a single body, an extremely deep groove (depth t2) for forming the X-ray absorbing portions 121 and 121 must be formed. Although it is difficult to form the width w2 and the gap g2 of 121 constant due to processing problems, if a method of manufacturing a plurality of divided grid blocks 12s having a small thickness and joining them is used, such accuracy is increased. It is easy to manufacture the amplitude type diffraction grating 12 in which the width w2 and the interval g2 are uniform in the thickness direction.

  There are various methods for joining the plurality of divided lattice blocks 12s. For example, in addition to molecular bonding by performing OH group treatment on the material surface at the hydrogen terminal, a method of heating to 200 ° C. and pressure welding, an adhesive it can be cited as a typical example of the method using a. In forming the grooves 51 and 52 in the plurality of divided lattice blocks 12s described above, patterning is preferably performed using exactly the same mask, and more specifically, it is preferably manufactured by the completely same method.

[Method of manufacturing amplitude-type diffraction grating by molding die]
Furthermore, a large number of amplitude type diffraction gratings 12 or divided grating blocks 12s can be easily manufactured by using a molding die 43 as shown in FIG. The molding die 43 shown in FIG. 8 (p1) is obtained by dissolving and removing the resin member 122 with a solvent or the like instead of removing the substrate 35 from the state with the substrate 35 in the stage of (p4) shown in FIG. As a result of the resin member 122 being removed in this way, the aforementioned X-ray absorption part 121 becomes the protruding part 42 protruding in a comb-tooth shape from the substrate 35, and the mold 43 can be manufactured.

  In the step (p1) of FIG. 8, an appropriate synthetic resin (for example, polymethylmethacrylate resin) 45 exhibiting a fluid state is filled in an appropriate container 44, and the molding die 43 is placed on the resin 45. , to enter from above the projecting portion 42 in the lower side. Then, as shown in (p2), when the molding die 43 is pulled up just before the resin 45 is cured, the groove forming body 53 in which the groove 51 is formed in the portion corresponding to the protruding portion 42 can be manufactured. After that, as shown in FIG. 8 (p <b> 3), the groove 51 is plated with gold (electroforming method) to form the X-ray absorbing portion 121 between the resin members 122. Thus the amplitude type diffraction grating 12 to divide the grid blocks 12s are formed.

  In this method, once the molding die 43 is made, a large number of groove forming bodies 53 having the same shape can be easily manufactured. Thereafter, only the X-ray absorbing portion 121 is formed in the groove 51 of the groove forming body 53. in well, it is suitable for cost reduction through mass production. Further, even when a large number of divided grid blocks 12s are manufactured by the method of FIG. 8 using the mold 43 and these are joined in the thickness direction as shown in FIG. 7, the dimensions of the divided grid blocks 12s (each groove forming body) 53) can be made exactly the same, so that the dimensional accuracy of the amplitude type diffraction grating 12 after bonding can also be improved.

[Modification]
The preferred examples of the method for manufacturing the diffraction gratings 11 and 12 of the present invention have been described above. However, the above embodiment can be modified as follows, for example.

  In the diffraction gratings 11 and 12 of the present embodiment, the X-ray absorbers 111 and 121 are made of gold, but are not limited to gold, and any material may be used. However, it is preferable to use a material having an excellent X-ray absorption ability, such as platinum, gold, silver, platinum, etc., because the same performance can be realized even with the diffraction gratings 11 and 12 having a small thickness.

  The X-ray Talbot interferometer using the X-ray diffraction gratings 11 and 12 according to the manufacturing method of the present embodiment is not limited to using synchrotron radiation as the X-ray source, but uses other small X-ray sources. Is also possible. In addition, as described above, the X-ray Talbot interferometer is suitable for a medical image diagnostic apparatus. However, this is only an example. In addition, an industrial nondestructive inspection apparatus, a food inspection apparatus, It is useful for various applications such as luggage inspection devices and imaging devices for animal experiments.

The conceptual diagram of the X-ray Talbot interferometer using the diffraction grating which concerns on the manufacturing method of this invention. (A) is a diagram showing an example of a Talbot interference image obtained by an X-ray Talbot interferometer, (b) is a diagram showing a differential phase image obtained by a fringe scanning method, and (c) is an example of an X-ray phase type CT. FIG. Schematic perspective view showing the two X-ray diffraction grating. Explanatory view showing step-by-step example of method of manufacturing a phase-type diffraction grating. Explanatory view showing step-by-step example of the production method of the amplitude type diffraction grating. Explanatory drawing which shows order for other examples of the manufacturing method of an amplitude type diffraction grating later on. Explanatory drawing which shows the example which manufactures an amplitude type diffraction grating with large thickness by joining a division | segmentation grating | lattice block to a thickness direction. Explanatory drawing which shows order for the example which manufactures an amplitude type | mold diffraction grating using a shaping | molding die later on.

Explanation of symbols

10 Sample 11 Phase-type diffraction grating 111 X-ray absorption part w1 Width of X-ray absorption part g1 Interval of X-ray absorption part t1 Thickness of phase-type diffraction grating 12 Amplitude-type diffraction grating 121 X-ray absorption part w2 Width of X-ray absorption part g2 X-ray absorption interval t2 Amplitude type diffraction grating thickness 122 Resin member 123 Holding member 12s Divided grating block

Claims (5)

A method of manufacturing a phase type diffraction grating and an amplitude type diffraction grating used in an X-ray Talbot interferometer,
Both diffraction gratings have a configuration in which X-ray absorption parts made of metal with a width of 2 μm or more and 10 μm or less are arranged at equal intervals of 2 μm or more and 10 μm or less. It is the same as the lattice,
The thickness of the phase type diffraction grating is 1 μm or more and 5 μm or less,
The thickness of the amplitude type diffraction grating is configured to be 25 μm to 100 μm ,
Amplitude diffraction grating
Deep grooves are formed in the resin by X-ray lithography (LIGA method) using an X-ray mask,
A method for producing a phase-type diffraction grating and an amplitude-type diffraction grating, which is produced by forming the X-ray absorption portion in the formed groove by electroforming . A method of manufacturing a phase type diffraction grating and an amplitude type diffraction grating used in an X-ray Talbot interferometer,
Both diffraction gratings have a configuration in which X-ray absorption parts made of metal with a width of 2 μm or more and 10 μm or less are arranged at equal intervals of 2 μm or more and 10 μm or less. It is the same as the lattice,
The thickness of the phase type diffraction grating is configured to be 1 μm or more and 5 μm or less,
The thickness of the amplitude type diffraction grating is configured to be 25 μm or more and 100 μm or less,
Amplitude diffraction grating
The resin layer is formed on the surface of the silicon layer which has been subjected to silicon oxide film, patterning is performed with respect to the resin layer by using a light science lithography mask, selectively removing the resin layer and the silicon oxide film,
A trench is formed in the silicon layer by performing ICP plasma etching on the surface of the silicon layer selectively exposed as described above.
Characterized in that it is produced by a Turkey to form the X-ray absorbing portion to the groove formed by the electroforming method, method of manufacturing a phase type diffraction grating and the amplitude type diffraction grating. A method of manufacturing a phase type diffraction grating and an amplitude type diffraction grating used in an X-ray Talbot interferometer,
The amplitude type diffraction grating is:
A molding die having a projecting portion as an X-ray absorbing portion formed by the amplitude type diffraction grating manufacturing method according to claim 1 or 2 ,
Using this mold, the groove forming body is molded,
It is obtained by forming the X-ray absorption part in the groove formed in the groove forming body by electroforming,
Manufacturing method of phase type diffraction grating and amplitude type diffraction grating. A method of manufacturing a phase type diffraction grating and an amplitude type diffraction grating used in an X-ray Talbot interferometer,
The amplitude type diffraction grating is:
A split grating block is manufactured by a method of manufacturing an amplitude type diffraction grating among the methods according to any one of claims 1 to 3.
A method of manufacturing a phase type diffraction grating and an amplitude type diffraction grating, which is obtained by joining the plurality of manufactured divided grating blocks in the thickness direction. A method of manufacturing a phase type diffraction grating and the amplitude type diffraction grating according to any one of claims 1 to 4, wherein the X-ray absorbing portion, platinum, gold, silver, a selected one of platinum A manufacturing method of a phase type diffraction grating and an amplitude type diffraction grating, characterized by comprising one or a combination of two or more.