Micropore optical system and associated production methods and x-ray imaging system

Abstract

The invention relates to a micropore optical system (MPO) for focusing X-rays onto an image plane positioned at a predetermined distance, or for creating a parallel beam of X-rays. The micropore optical system (MPO), which comprises a matrix array (23), incorporates: • a plurality of channels (10) through which the X-rays can be transmitted and reflected; and • a blocking area in which the matrix array (23) is opaque to X-rays, the blocking area being arranged at least in a central area of the micropore optical system (MPO).

Description

[0001] MICRO-PORE OPTICS, MANUFACTURING PROCESSES AND SYSTEM

[0002] X-RAY IMAGING ASSOCIATED WITH

[0003] FIELD OF INVENTION

[0004] The invention relates to the field of X-ray imaging and more particularly to micro-pore optics for focusing X-rays or for creating a parallel X-ray beam, also known as MPOs (micro-pore optics) in the English-language literature. Furthermore, the invention also relates to methods for manufacturing an MPO.

[0005] While MPOs are classically used in X-ray telescopes, the invention finds applications not only in the field of space imaging, but also in X-ray imaging and analysis applications, such as X-ray diffraction (XRD for "x-ray diffractometer" or "x-ray diffraction" in the Anglo-Saxon literature) or X-ray fluorescence spectroscopy (XRF for "x-ray fluorescence" in the Anglo-Saxon literature).

[0006] This invention therefore presents a multitude of potential applications.

[0007] STATE OF THE ART

[0008] In the field of space imaging, the goal is to observe the universe across the entire electromagnetic spectrum. To do this, astronomers record electromagnetic waves emanating from the universe using telescopes, parabolic antennas, microwave antennas, and other instruments.

[0009] Observing X-rays is a major challenge, however, because these electromagnetic waves are strongly absorbed by Earth's atmosphere and do not reach the surface. Furthermore, creating optics to capture and focus X-rays is particularly complex, as they are difficult to manipulate with conventional optical techniques due to their very high energy. To address these technical problems, satellites have been designed to observe X-rays using grazing incidence optics. Unlike optical telescopes and binoculars, which use refraction to bend and focus light, grazing incidence optics use reflection.

[0010] Indeed, X-rays tend to penetrate matter rather than be refracted. However, if they strike a surface at a very small angle, almost parallel to it, they can be reflected. This angle is so small that it is often measured in arcminutes or arcseconds, reflecting the requirement that the rays be nearly parallel to the reflecting surface.

[0011] To capture and focus X-rays in grazing incidence optics, micropore optics (MPOs) were developed. These MPOs are also known as "lobster-eye" optics in English-language literature due to their similarity to the structure of a lobster's eye.

[0012] MPOs are typically composed of an array formed by thousands of straight, narrow, parallel channels, usually with a square structure. This configuration allows X-rays from different directions to be reflected and focused onto a detector or focal point, thus increasing the efficiency of X-ray capture.

[0013] Figure 1 of the prior art illustrates a MPO with square-section channels (10). Each channel (10) has sides of 20 micrometers and is arranged in a similarly square pattern with walls (11) 6 micrometers thick between each channel (10). The length of each channel (10) is, for example, approximately 1 millimeter.

[0014] MPOs are generally manufactured from glass blocks that are drawn. More specifically, primary fibers are produced with a core soluble in an acid, for example, pure glass, and a sheath surrounding the core insoluble in the same acid, for example, lead glass resistant to multiple acids. These primary fibers are obtained by drawing them to a desired initial diameter and then assembled to form a preform composed of a large number of primary fibers.

[0015] Secondary fibers, derived from the first base material, are then obtained by stretching the preform to a second desired diameter to create a second elongated base material. This second elongated base material is then cut transversely along a specific cutting plane. This cutting step produces multiple base wafers. These base wafers are then soaked in acid to dissolve the core, exposing the microchannels. Thus, after the core is dissolved, the base wafers form microchannel wafers whose core is formed by the fusion of the sheaths of each fiber involved in the manufacturing process.

[0016] A MPO can be flat, but it is also possible to create non-planar MPOs, that is, curved along a radius of curvature, which can also be elliptical or cylindrical. The channels can then be slightly deformed, while retaining their square appearance.

[0017] To achieve focusing with a MPO, the goal is for photons to be reflected twice, in two perpendicular directions. At the image plane, photons coming from the same source point, or photons coming from the same direction at infinity, then concentrate around a point, called the spot, which produces the focusing phenomenon.

[0018] As illustrated in Figure 3 of the prior art, photons arriving from the same source enter the channel's entrance section (10) at different points: these are zones 0, 1, and 2 in Figure 3. These differences in entry points induce variations in the number of reflections within the channel (10). The squares 0, 1, and 2 of the image plane Pi, positioned at a distance F from the center of the channel's length L, illustrate the parts of the image plane Pi that are affected after zero, one, or two reflections. These reflection numbers depend on the photon's point of entry into the channel's entrance section Se and the channel's width d. The intensity captured on the image plane Pi also depends on the distance F from the image plane Pi to the channel (10).

[0019] However, it is impossible to guarantee exactly two reflections for each photon entering a channel (10) because photons can enter zones 0 and 1 at the entrance section Se of the channel (10), which will induce zero or only one reflection. Besides the cases illustrated in Figure 3, triple, quadruple, etc., reflections can also be observed.

[0020] Rays that pass directly through the channels (10) without being reflected or focused in any way arrive at the image plane Pi with a diffuse distribution. As illustrated in Figure 2, some rays graze the upper surface of the channels (10) and are reflected downwards onto the detector (12). Similarly, some rays graze the lower surface of the channels (10) and are reflected upwards onto the detector (12). The rays from these two mirrors converge at the same height on the detector (12), but if they have not been focused laterally, they are spread horizontally. This type of ray therefore appears on the detector (12) as a horizontal bar of moderate intensity. Likewise, some rays are reflected only by a vertical surface and no horizontal surface, forming a vertical bar on the image plane Pi.

[0021] Finally, some rays arrive in the corner to be reflected by a vertical and then horizontal face, or vice versa. These doubly reflected rays pass diagonally towards the center of the detector, forming a very intense central focal point.

[0022] More precisely, as illustrated in Figure 4, photons from a point source (13) passing through a channel (10) of a point-source image (PSI) can impact the image plane Pi with no reflection (according to the impact R0), with a single reflection (according to the impacts RI forming the cross), or with two reflections (so as to contribute to the spot R2). The scaling ratio between the point source (13), the PSI, and the image plane Pi is preserved. Thus, there exists a ratio M that corresponds to the distance L between the point source (13) and the image plane (Pi), divided by the distance Ls between the point source (13) and the PSI. This ratio M is applicable to the spatial difference between the PSI and the image plane Pi, so that, in Figure 4, X = M*x and Y = M*y, with X and Y being the coordinate systems of the image plane Pi, and x and y being the coordinate systems of the PSI.

[0023] Thus, rays that do not concentrate towards the focal point contribute to cross-shaped noise and a diffuse background at the image plane, as illustrated in Figure 5.

[0024] This problem of noise in the form of a cross is widely discussed in the state of the art and it is a problem that has not really been solved for many years.

[0025] In the publication HN Chapman, KA Nugent, SW Wilkins; “X-ray focusing using square channel-capillary arrays”, Rev. Sci. Instrum. (1 June 1991); 62 (6): 1542-1561, the authors suggest optimizing the MPO design by adjusting parameters such as channel aspect ratio, surface reflectivity, and geometry to limit the effect of cross-shaped noise. Circular arrangements have also been proposed, as described in the publication GJ Price, AN Brunton, MW Beijersbergen, GW Fraser, M. Bavdaz, J.-P. Boutot, R. Fairbend, S.-O. Flyckt, A. Peacock, E. Tomaselli,

[0026] In this type of arrangement, a single reflection off a wall of a channel forming a circular element is desired. However, some photons can pass through such a MPO without undergoing any reflection. These photons then contribute to a diffuse background at the image plane.

[0027] Even though it is less intense than in the case of a square configuration, this diffuse background remains too intense for most optical applications.

[0028] In the publication R. Willingale, GW Fraser, and JF Pearson "Optimization of square pore optics for the x-ray spectrometer on Bepi-Columbo", Proc. SPIE 5900, Optics for EUV, X-Ray, and Gamma-Ray Astronomy II, 590012 (8 September 2005), several channel arrangement structures are proposed to limit the effect of cross-shaped noise.

[0029] The publication R. Willingale, JF Pearson, A. Martindale, CH Feldman, R. Fairbend, E. Schyns, S. Petit, JP Osborne, PT O'Brien, "Aberrations in square pore micro-channel optics used for x-ray lobster eye telescopes", Proc. SPIE 9905, Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray, 99051Y (18 July 2016) describes the use of a software model to manage the notions of noise or blur on the detector.

[0030] The publication by M. Gailhanou, P. Sarrazin, and D. Blake, "Modeling of x-ray fluorescence full field imaging using planar square pore micro-channel plate optics," Appl. Opt. 57, 6795-6807 (2018), proposes two original solutions to limit the effect of cross-shaped noise. These solutions involve capturing X-rays while rotating the channels at a random angle, or taking successive images while rotating the MPO to smooth the cross, that is, to transform it into uniform noise. These solutions do not modify the total noise intensity, nor, more importantly, do they eliminate it in the vicinity of the spot. The publication by Songwu Peng, Yizhong Ye, Fei Wei, Zuhua Yang, Yihong Guo, and Tianran Sun, "Numerical model built for the simulation of the earth magnetopause by lobster-eye-type soft X-ray imager onboard SMILE satellite," Opt.Express 26, 15138-15152 (2018) describes a simulation method that includes channel manufacturing errors to more accurately characterize image quality.

[0031] The publication Songwu Peng, Fei Wei, Yihong Guo, Yizhong Ye, “Preliminary geometric parameters optimization of lobster-eye-type wide field of view soft x-ray imager,” Opt. Eng. 58(9), 093101 (2019) analyzes the channel curvature radius errors to limit the effect of cross-shaped noise.

[0032] The publication Jin Li, Takanori Sakamoto, Motoko Serino, Daisuke Yonetoku, Tatsuya Sawano, Ikuyuki Mitsuish, Tatehiro Mihara, "X-ray performance and simulation study of lobster eye optics", Proc. SPIE 11444, Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray, 114447C (13 December 2020) describes the use of a software model to manage the notions of noise or blur on the detector by integrating the non-uniformity of the curvature of the channels.

[0033] The publication An, Siwen & Krapohl, David & Thôrnberg, B & Roudot, R & Schyns, E & Norlin, Bôrje. (2023). Characterization of micro pore optics for full-field X-ray fluorescence imaging. Journal of Instrumentation. 18. C1017. 10.1088 / 1748-0221 / 18 / 01 / C01017 proposes a fast Fourier transform image processing to limit the effect of cross-shaped noise.

[0034] In conclusion, while the state of the art offers a number of solutions to mitigate or spread this cross-shaped noise problem, such as rotating the channels by a random angle or taking successive images by rotating the MPO, these solutions only distribute the noise photons randomly around the spot, without significantly reducing it.

[0035] These solutions may be relevant for space applications, where focal lengths are large, because the noise level is relatively low. However, when focal lengths are relatively short, state-of-the-art solutions are insufficient, typically for X-ray imaging and analysis applications, such as X-ray diffraction or X-ray fluorescence spectroscopy.

[0036] The technical problem of the invention is therefore to find how to significantly reduce the noise from an MPO so that the MPO can be used for applications in which focal lengths are relatively short.

[0037] DESCRIPTION OF THE INVENTION

[0038] To address this technical problem, the invention proposes to make a central area of ​​the MPO matrix opaque to X-rays. Even considering the multiple possible reflections that can impact the image plane of an MPO, it has been shown that this solution eliminates the photons that generate noise in the noisiest area of ​​the image plane, i.e., the area around the spot, the surface of which is defined by the surface area of ​​the noise zone to be reduced on the image plane.

[0039] Furthermore, in an application of creating a parallel beam, such as X-ray diffraction, this solution eliminates photons close to the optical axis, and therefore improves beam divergence.

[0040] Thus, according to a first aspect, the invention relates to a micro-pore optic for focusing X-rays onto an image plane positioned at a predetermined distance or for creating a parallel beam of X-rays, said micro-pore optic comprising a matrix integrating: a plurality of channels through which X-rays can be transmitted and reflected; and a shutter zone in which the matrix is ​​opaque to X-rays, said shutter zone being disposed at least in a central area of ​​said micro-pore optic.

[0041] Blocking off the central area thus reduces the noise present around the spot.

[0042] The area of ​​the central zone can be determined based on the noise reduction area on the image plane and the distance between the image plane and the micropore optics. Shuttering is particularly effective when the matrix has a circular arrangement. In this embodiment, the individual pixels of the matrix are arranged regularly in a concentric pattern. The individual pixels may be circular. With a circular arrangement, the pixel(s) that constitute the shutter zone include at least one circular area centered on the center of the matrix.

[0043] When the micro-pore optics have a square arrangement, the obturation area is preferentially arranged along two orthogonal bands, these bands being centered on the width and length of said matrix.

[0044] In this embodiment, the vertical band limits the photons contributing to the horizontal arm of the crosshairs, while the horizontal band limits the photons contributing to the vertical arm of the crosshairs. To define the width of each band, the size of the noise area to be reduced can be measured on the image plane, and then the width of each band can be determined from a ratio M. This ratio M is determined at least from the size of the noise area to be reduced and the distance between the image plane and the micropore optics (MPO) (for example, the ratio M described in relation to Figure 4 of the prior art). Furthermore, the two orthogonal bands of the shutter area limit the photons contributing to the diffuse background noise around the spot.

[0045] It can be advantageous to opacify, either as an alternative to or in addition to the two vertical and horizontal bands, an area defined by a hyperbolic contour, thus forming a cross with hyperbolic contours. The mathematical definition of these hyperbolic contours can use the x*y product of the channel positioning markers, as illustrated in Figure 4 of the prior art. Thus, each channel for which the x*y product is less than a constant can be blocked. Indeed, the probability that a photon arriving at a point (x, y) of the MPO will be reflected back to the spot is proportional to the x*y product. Such blocking therefore limits the noise photons in an area around the spot and also reduces the noise level beyond it, with a very limited impact on the flux reaching the spot.

[0046] Furthermore, the source can be positioned on the focal plane of the micro-pore optics to provide a collimated beam. In a collimation application, typically for X-ray imaging and analysis applications, the presence of bands centered on the width and length of the micro-pore optics suppresses noise photons having a divergence in the vertical and horizontal planes of less than 1 / 2*A / Ls, where Ls corresponds to the distance between the source and the MPO as illustrated in Figure 4 of the prior art, and A is the dimension of the blocked area.

[0047] Alternatively, the position of said source relative to said micro-pore optics and its focal plane can be chosen so as to produce a focused beam.

[0048] For certain applications, micro-pore optics can also exhibit a positive or negative radius of curvature along an optical axis.

[0049] According to a first embodiment, the obturation zone is created by an obturation plate interposed between the plurality of channels. In this embodiment, several conventional mini-MPOs are assembled around an opaque structure. This results in an MPO extending over only a portion of the matrix, with all channels open in the four corners, and an obturation plate forming a central cross. In this case, a single mini-MPO can be placed in each corner of the matrix, or several mini-MPOs can be placed in each corner, thus requiring the use of 4, 16, or 36 mini-MPOs. In this embodiment, the rows and columns of the matrix are therefore created by both the obturation plate and the individual mini-MPOs.

[0050] According to a second embodiment, the obturation zone is created by an obturation plate fixed to a portion of said plurality of channels. In this embodiment, the MPO matrix is ​​created in a first step in which all the channels are opened, and the obturation zone is created in a second step by applying the obturation plate.

[0051] In both embodiments, the shutter plate can be made of lead or any other material opaque to X-rays. In the second embodiment, the shutter plate can be printed on a film deposited on said micro-porous optics or printed directly on said micro-porous optics.

[0052] In a third embodiment, the obturation zone is created by apodizing a portion of said plurality of channels. In this embodiment, certain channels of the matrix are thus obturated by apodization, that is, a structural modification of the channels in the obturation zone, carried out before or after matrix formation, such that the apodized channels are opaque to X-rays.

[0053] To achieve such apodization, several distinct processes can be used. For example, three-dimensional printing can be used in which the apodized channels are obtained with a printing pattern configured to create said channels forming the said obturation zone of the matrix.

[0054] It is also possible to modify the standard procedure for creating the obturated canals. This procedure may involve the following steps:

[0055] • production of transmission fibers with a core soluble in an acid and a sheath surrounding the core insoluble in the same acid;

[0056] • production of sealing fibers with a core and a sheath surrounding the core insoluble in said acid;

[0057] • assembly of the transmission fibers with the sealing fibers so that said sealing fibers are arranged at least in a central area of ​​said micro-pore optics (MPO);

[0058] • cross-sectional cutting of the assembly to a desired thickness to form a base plate; and

[0059] • chemical attack of the base wafer so as to open only the transmission fiber channels.

[0060] In this channel fabrication process, it is possible to use several successive drawings and assemblies of the transmission and obturation fibers, or to apply specific treatments to the MPOs, such as treatments aimed at controlling the roughness of the open channels. To do this, it is possible to deposit a metallization inside the channels or to use a glass forming technique that involves heating the channels until they become soft enough to conform to the shape of a mold, a technique also known as "slumping" in English.

[0061] In another aspect, the invention also relates to an X-ray imaging system for a sample, comprising:

[0062] • an X-ray source configured to illuminate said sample through micro-pore optics according to the first aspect of the invention; and

[0063] • a detector placed on a plane of reflection of the rays emanating from said sample.

[0064] Alternatively, the X-ray imaging system for a sample includes:

[0065] • an X-ray source configured to illuminate said sample;

[0066] • a micro-pore optic according to the first aspect of the invention; and

[0067] • a detector placed on the image plane of said micro-pore optics, said micro-pore optics being configured to collect photons from the sample and transmit them to the detector.

[0068] To improve the performance of the micropore optics, a mask can be placed after the micropore optics. This mask further blocks noise photons in the area of ​​the image plane where cross noise photons arrive, that is, in the part of the image plane not protected from this noise by the channel blocking.

[0069] Preferably, the micro-pore optics is placed between a first X-ray emitting element, such as said X-ray source or said sample, and a second X-ray receiving element, such as said sample or said detector;

[0070] • said first element being placed at a distance L1 from said micro-pore optics and having a surface composed of a first size Al and a second size B 1;

[0071] • said second element being placed at a distance L2 from said micro-pore optics and having a surface composed of a third size A2 and a fourth size B2; • the obturation zone of said micro-pore optics being arranged according to two orthogonal bands, a first band with a minimum size dl along the first axis, and a second band with a minimum size d2 along the second axis;

[0072] • the first minimum size equal to dl being greater than (L1 Al + L2 A2) / (5*(L1 + L2)), in particular greater than (LI Al +L2 A2) / (3*(L1 + L2)) and preferably greater than (Ll Al + L2 A2) / (Ll + L2);

[0073] • the second minimum size equal to d2 being greater than (L1 B1 + L2 B2) / (5*(L1 + L2)), in particular greater than (L1 B1 + L2 B2) / (3*(L1 + L2)) and preferably greater than (L1 B1 + L2 B2) / (L1 + L2).

[0074] SUMMARY DESCRIPTION OF THE FIGURES

[0075] The manner in which the invention can be implemented and the resulting advantages will be more clearly shown in the following implementation examples, given by way of illustration and not limitation, in support of the attached figures.

[0076] Figure 1 is a perspective view of the channels of a prior art micro-pore optics;

[0077] Figure 2 illustrates a cross-sectional view of the channels of the micro-pore optics of Figure 1 which contribute to some of the cross noise;

[0078] Figure 3 illustrates perspective views of possible reflections inside a state-of-the-art micro-pore optic;

[0079] Figure 4 illustrates the dispersions between a source, a micro-pore optic and an image plane according to the prior art;

[0080] Figure 5 illustrates the image plane of a prior art micro-pore optic;

[0081] Figure 6 illustrates the image plane obtained with a micro-pore optic according to one embodiment of the invention;

[0082] Figure 7 illustrates a top view of a micro-pore optic according to a first embodiment of the invention;

[0083] Figure 8 illustrates a top view of a micro-pore optic according to a second embodiment of the invention;

[0084] Figure 9 illustrates a top view of a micro-pore optic according to a third embodiment of the invention; Figure 10 illustrates a top view of a micro-pore optic according to a fourth embodiment of the invention;

[0085] Figure 11 illustrates a cross-sectional view of a micro-pore optic according to an embodiment of the invention having a first radius of curvature;

[0086] Figure 12 illustrates a cross-sectional view of a micro-pore optic according to an embodiment of the invention having a second radius of curvature;

[0087] Figure 13 illustrates a schematic representation of a first X-ray imaging system of a sample incorporating a micro-pore optic according to the invention;

[0088] Figure 14 illustrates a schematic representation of a second X-ray imaging system for a sample incorporating micro-pore optics according to the invention; and

[0089] Figure 15 schematically illustrates an X-ray imaging system according to an embodiment of the invention, the system comprising a micro-pore optic according to an embodiment of the invention.

[0090] DETAILED DESCRIPTION OF THE INVENTION

[0091] As illustrated in Figures 7 to 10, the invention thus proposes a micropore optic (MPO) for focusing X-rays onto an image plane Pi or for creating a parallel beam of X-rays. As illustrated in Figures 3 and 4 of the prior art, this micropore optic is intended to be positioned at a predetermined distance F from the image plane Pi. Unlike a conventional micropore optic, the micropore optic of the invention comprises a matrix (23) with a shutter zone in which the matrix is ​​opaque to X-rays. This shutter zone can simply be a central region of the MPO, particularly when the micropore optic has a circular arrangement. In addition to the shutter zone, the matrix also incorporates a plurality of channels (10) through which X-rays can be transmitted and reflected, similar to the channels of a conventional micropore optic.

[0092] To determine the area of ​​the central zone, it suffices to determine the noise area to be reduced on the image plane Pi when the micropore optics do not have a blocking zone, and then apply a principle of homothety with respect to the distance F between the image plane Pi and the micropore optics MPO. In a square arrangement, as illustrated in Figures 7 to 10, cross noise therefore requires the preferential use of a blocking zone in the form of two orthogonal bands. These orthogonal bands are illustrated in Figure 7 with two bands in which the channels are blocked. Alternatively, or in addition to these two bands, it is also possible to use a cross with hyperbolic contours, as illustrated in Figure 8.

[0093] The cross with a straight or hyperbolic contour can be obtained with apodized channels (21). Apodizing these channels corresponds to a sealing process so that these channels are opaque to X-rays. To achieve this, it is possible to fabricate the micro-pore optics matrix using three-dimensional printing, in which the printing pattern incorporates only open channels (10) in the areas where the channels do not need to be apodized.

[0094] Alternatively, it is possible to carry out the apodization after the micropore optics have been made, for example by placing a lead obturation plate over the desired obturation area.

[0095] Furthermore, micropore optics can also be fabricated by modifying the conventional fabrication process to position the apodized channels (21) at the desired locations. To achieve this, the fabrication of micropore optics fibers typically involves steps of creating transmission fibers with an acid-soluble core and a cladding surrounding the acid-insoluble core, followed by steps of assembling and drawing these fibers to obtain transmission fibers with a predetermined diameter.

[0096] Furthermore, in parallel with the production of these transmission fibers, it is possible to produce the sealing fibers using the same process, provided that the sheath and core are insoluble in acid. Subsequently, the transmission and sealing fibers can be assembled in the desired pattern to form the matrix (23), as illustrated in the embodiments shown in Figures 7 or 8.

[0097] Following this assembly phase, the assembly can be cut transversely to a desired thickness to form a base plate, before implementing a conventional step in which a chemical etch of the base plate opens the transmission fiber channels. After this chemical etch process, the resulting MPO can therefore be an MPO with obturator fibers forming the apodized channels (21), as illustrated in Figures 7 or 8. Alternatively, mini-MPOs (25) can be placed around an obturator plate (24) forming the obturator zone, as illustrated in Figures 9 or 10. In these embodiments, a cross-shaped obturator plate (24) is positioned in the center of the matrix (23), and the four corners of the matrix are formed by mini-MPOs covering the rest of the matrix.In the example in Figure 9, one mini-MPO is placed at each corner of the matrix (23), whereas in the embodiment of Figure 10, four mini-MPOs (25) are placed in each corner of the matrix (23). Alternatively, each corner of the matrix could also incorporate nine or more mini-MPOs (25).

[0098] In addition, the sealing plate (24) may have other shapes than those illustrated in Figures 9 and 10, for example with hyperbolic contours or arranged only on the central area of ​​the MPO, for example when the MPO has a circular arrangement.

[0099] In addition to the apodization or obturation performed on certain parts of the MPO matrix (23), it is also possible to imprint a specific radius of curvature along the optical axis Ao of the MPO, as illustrated in Figures 11 and 12. More specifically, in Figure 11, the MPO has a positive radius of curvature along the optical axis Ao, so as to provide a collimated beam (14) on the image plane Pi. Alternatively, in the embodiment illustrated in Figure 12, the micro-pore optics MPO has a negative radius of curvature along the optical axis Ao, so as to provide a focused beam (15) on a point, or at least a small area, of the image plane Pi.

[0100] The invention thus finds a particularly advantageous application for limiting noise in systems using a MPO. Indeed, as illustrated in Figure 6, the cross noise obtained on an MPO of the invention with a square arrangement is limited compared to the cross noise observed with a prior art MPO.

[0101] This noise limitation opens up new applications for MPOs where noise is currently a limiting factor. For example, it is now possible to design efficient X-ray imaging systems to detect the properties of a sample (16). As illustrated in Figure 13, an X-ray source (17) can be placed opposite a sample (16), so that the X-ray diffraction on this sample (16) passes through an MPO before reaching a detector (12). Alternatively, instead of the X-ray imaging system shown in Figure 13, the MPO can be placed between the X-ray source (17) and the sample (16), with the detector (12) directly capturing the intensity of the point reflected by the sample (16), as illustrated in Figure 14.

[0102] In addition, it is also possible to place a mask between the MPO micro-pore optics and the detector, so as to mask part of the image plane and further limit the noise measured on it.

[0103] In conclusion, the invention proposes to apodize or opacify certain parts of a micropore optics array to limit noise on its image plane, particularly around the spot, or to improve the quality of a parallel beam (especially around the principal direction of this beam). Reducing noise on the image plane thus improves the overall performance of the MPO and opens up a large number of new applications, notably X-ray analysis of samples.

[0104] Dimensions of the sealing area

[0105] With reference to Figure 15, one aspect of the invention is an X-ray imaging system comprising an optical axis (18). The X-ray imaging system comprises consecutively, along the optical axis (18), a first X-ray emitting element (19), a micro-pore optic (MPO), and a second X-ray receiving element (20).

[0106] Referring to Figure 13, the first X-ray emitting element (19) can be a sample (16) intended to be imaged. The second X-ray receiving element (20) can be a detector (12).

[0107] Referring to Figure 14, the first X-ray emitting element (19) can be an X-ray source (17). The second X-ray receiving element (20) can be a sample (16) intended for imaging. Referring to Figure 15, the first element (19) can have a first size equal to A1 in a plane perpendicular to the optical axis (18) and along a first axis, and a second size equal to B1 in the plane perpendicular to the optical axis (18) and along a second axis, perpendicular to the first axis. The first and second sizes are, for example, useful sizes of the first element (19).

[0108] The second element (20) can have a third size equal to A2 in a plane perpendicular to the optical axis (18) and along the first axis, and a fourth size equal to B2 in the plane perpendicular to the optical axis (18) and along the second axis, which is perpendicular to the first axis. The third and fourth sizes are, for example, useful sizes of the second element (20).

[0109] The first element (19) is placed at a distance L1 from the MPO micropore optics along the optical axis (18). The second element (20) is placed at a distance L2 from the MPO micropore optics along the optical axis 18.

[0110] As illustrated in Figure 15, the MPO micropore optics can include a sealing zone with two orthogonal bands, these bands being centered on the width and length of the matrix (23) of the MPO micropore optics. Thus, the MPO micropore optics of Figure 15 comprises, in a plane perpendicular to the optical axis (18), a first band with a minimum size d1 along the first axis, and a second band with a minimum size d2 along the second axis.

[0111] The first minimum size, equal to dl, can be greater than (L1 Al + L2 A2) / (5*(L1 + L2)), specifically greater than (L1 Al + L2 A2) / (3*(L1 + L2)), and preferably greater than (L1 Al + L2 A2) / (Ll + L2). Thus, the majority of photons contributing to diffuse background noise in the image along the first axis are filtered by the MPO micro-pore optics.

[0112] The second minimum size, equal to d2, can be greater than (L1 B1 + L2 B2) / (5*(L1 + L2)), specifically greater than (L1 B1 + L2 B2) / (3*(L1 + L2)), and preferably greater than (L1 B1 + L2 B2) / (L1 + L2). Thus, the majority of photons contributing to diffuse background noise in the image along the second axis are filtered by the MPO micro-pore optics.

Claims

DEMANDS 1. Micro-pore optics (MPO) for focusing X-rays onto an image plane (Pi) positioned at a predetermined distance (F) or for creating a parallel X-ray beam, said micro-pore optics (MPO) comprising a matrix (23) integrating: • a plurality of channels (10) through which X-rays can be transmitted and reflected; and • a blocking zone in which the matrix (23) is opaque to X-rays, said blocking zone being disposed at least in a central zone of said micro-pore optics (MPO).

2. Micropore optics (MPO) according to claim 1, wherein the matrix (23) has a square arrangement.

3. Micro-pore optics (MPO) according to claim 2, wherein the obturation zone is arranged along two orthogonal bands, these bands being centered on the width and length of said matrix (23).

4. Micro-pore optics (MPO) according to claim 2 or 3, wherein the obturation zone is arranged in a cross with hyperbolic contours.

5. Micropore optics (MPO) according to claim 1, wherein the matrix (23) has a circular arrangement.

6. Micro-pore optics (MPO) according to any one of claims 1 to 5, wherein the obturation zone is made by an obturation plate (24) intercalated between the plurality of channels (10).

7. Micro-pore optics (MPO) according to any one of claims 1 to 5, wherein the obturation zone is achieved by an obturation plate fixed on a part of said plurality of channels (10).

8. Micro-pore optics (MPO) according to any one of claims 1 to 5, wherein the obturation zone is achieved by apodization of a portion of said plurality of channels (10).

9. Micropore optics (MPO) according to any one of claims 1 to 8, wherein the micropore optics (MPO) has a positive or negative radius of curvature about an optical axis (Ao).

10. A method for producing a micropore optic (MPO) according to claim 8, wherein the method comprises the following steps: • production of transmission fibers with a core soluble in an acid and a sheath surrounding the core insoluble in the same acid; • production of sealing fibers with a core and a sheath surrounding the core insoluble in said acid; • assembly of the transmission fibers with the sealing fibers so that said sealing fibers are arranged at least in a central area of ​​said micro-pore optics (MPO); • cross-sectional cutting of the assembly to a desired thickness to form a base plate; and • chemical attack of the base wafer so as to open only the transmission fiber channels.

11. Method of making a micro-pore optic (MPO) according to claim 8, wherein the micro-pore optic (MPO) is made by three-dimensional printing with a printing pattern configured to make obturated channels (21) forming said obturating zone of the matrix (23).

12. X-ray imaging system for a sample (16), comprising: • an X-ray source (13, 17) configured to illuminate said sample (16) through a micropore optics (MPO) according to any one of claims 1 to 9; and • a detector (12) placed on a plane of reflection of the rays from said sample 13. X-ray imaging system for a sample (16), comprising: • an X-ray source (13, 17) configured to illuminate said sample (16); • a micropore optics (MPO) according to any one of claims 1 to 9; and • a detector (12) placed on the image plane (Pi) of said micro-pore optics (MPO), said micro-pore optics (MPO) being configured to collect photons from the sample (16) to transmit them to the detector (12).

14. X-ray imaging system according to claim 12 or 13, wherein said imaging system comprises a mask disposed between the micropore optics (MPO) and the detector (12) so as to mask a part of the image plane (Pi) at the level of said detector (12).

15. X-ray imaging system according to any one of claims 12 to 14, wherein said micro-pore optics (MPO) is placed between a first X-ray emitting element (19), such as said X-ray source (17) or said sample (16) and a second X-ray receiving element (20), such as said sample (16) or said detector (12); • said first element (19) being placed at a distance L1 from said micropore optics (MPO) and having a surface composed of a first size Al and a second size B 1; • said second element (20) being placed at a distance L2 from said micropore optics (MPO) and having a surface composed of a third size A2 and a fourth size B2; • the obturation zone of said micro-pore optics (MPO) being arranged according to two orthogonal bands, a first band with a minimum size dl along the first axis, and a second band with a minimum size d2 along the second axis; • the first minimum size equal to dl being greater than (L1 Al + L2 A2) / (5*(L1 + L2)), in particular greater than (L1 Al + L2 A2) / (3*(L1 + L2)) and preferably greater than (L1 Al + L2 A2) / (L1 + L2); • the second minimum size equal to d2 being greater than (L1 B1 + L2 B2) / (5*(L1 + L2)), in particular greater than (L1 B1 + L2 B2) / (3*(L1 + L2)) and preferably greater than (L1 B1 + L2 B2) / (L1 + L2).

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