MICRO-PORE OPTICS, MANUFACTURING PROCESSES AND ASSOCIATED X-RAY IMAGING SYSTEMS

Abstract

The invention relates to a micropore optic (MPO) for focusing X-rays onto an image plane positioned at a predetermined distance or for creating a parallel X-ray beam, said micropore optic (MPO) comprising a matrix (23) integrating: a plurality of channels (10) through which X-rays can be transmitted and reflected; and a shutter zone in which the matrix (23) is opaque to X-rays, said shutter zone being disposed at least in a central region of said micropore optic (MPO), the area of ​​said central region being determined as a function of a noise area to be reduced on the image plane, and the distance between the image plane and said micropore optic (MPO). Figure 9.

Description

Title of the invention: MICROPORE OPTICS, MANUFACTURING METHODS AND ASSOCIATED X-RAY IMAGING SYSTEM Scope of the invention

[0001] The invention relates to the field of X-ray imaging and more particularly to micropore optics for focusing X-rays or for creating a parallel beam of X-rays, also called MPOs for "micropore optics" in the English-language literature. Furthermore, the invention also relates to methods for manufacturing an MPO.

[0002] 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).

[0003] This invention therefore presents a multitude of potential applications. State of the art

[0004] In the field of space imaging, the aim is to observe the universe across the entire electromagnetic spectrum. To do this, astronomers record electromagnetic waves from the universe using telescopes, parabolic antennas, microwave antennas...

[0005] X-ray observation, however, presents a major challenge because these electromagnetic waves are strongly absorbed by the Earth's atmosphere and do not reach the Earth's surface. Furthermore, creating optics to capture and focus X-rays, which are difficult to manipulate with conventional optical techniques due to their very high energy, is particularly complex. To address these technical problems, satellites have been designed to observe X-rays using a grazing incidence optics technique.

[0006] Unlike optical glasses and telescopes which use refraction to deflect and focus light, grazing incidence optics use reflection.

[0007] Indeed, X-rays tend to penetrate matter rather than be refracted by it. 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 need for the rays to be almost parallel to the reflecting surface.

[0008] To capture and focus X-rays in grazing incidence optics, micro-pore optics (MPOs) have been developed. These MPOs are also known as "lobster-eye" optics in the English-language literature due to their similarity to the structure of a lobster's eye.

[0009] MPOs are classically composed of a matrix formed by thousands of straight, narrow, parallel channels, typically with a square structure. This configuration makes it possible to reflect and focus X-rays coming from different directions towards a detector or focal point, thus increasing the efficiency of X-ray capture.

[0010] Fig. 1 of the prior art illustrates a MPO with square-section channels (10). Each channel (10) has sides of 20 micrometers and they are arranged in a similarly square pattern with walls (11) of a thickness of 6 micrometers between each channel (10). The length of each channel (10) is, for example, approximately 1 millimeter.

[0011] MPOs are generally manufactured from glass blocks that are drawn. More specifically, first 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 a plurality of acids. These first fibers, called primary fibers, are obtained by drawing them to a first desired diameter and then assembled to form a preform composed of a large number of primary fibers.

[0012] Secondary fibers, derived from the first base material, are then obtained by drawing the preform to a second desired diameter in order to produce a second elongated base material. The second elongated base material is then cut transversely along a specific cutting plane.

[0013] This cutting step allows for the production of 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 body is formed by the fusion of the sheaths of each fiber involved in the manufacturing process.

[0014] A MPO can be planar, 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.

[0015] To achieve focusing with an MPO, it is desired that the photons are reflected twice, in two perpendicular directions. At the level of the plane image, 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 phenomenon of focusing.

[0016] As illustrated in Figure 3 of the prior art, photons arriving from the same source enter the channel (10) at different points: these are zones 0, 1, and 2 in Figure 3. These points of entry induce variations in the number of reflections within the channel (10). The squares 0, 1, and 2 of the image plane Pi, located at a distance F from the center of the length L of the channel (10), illustrate the parts of the image plane Pi that are affected after zero, one, or two reflections. These numbers of reflections depend on the point of entry of the photon into the channel (10) and on the channel width d. The intensity captured on the image plane Pi also depends on the distance F of the image plane Pi from the channel (10).

[0017] 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 [Fig. 3], triple, quadruple, etc. reflections can also be observed.

[0018] The rays which pass directly through the channels (10) without being reflected or focused in any way, arrive on the image plane Pi with a diffuse distribution.

[0019] As illustrated in [Fig. 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.

[0020] Finally, some rays arrive in the corner to be reflected by a vertical face and then a horizontal face or vice versa. These doubly reflected rays pass diagonally towards the center of the detector, forming a very intense central focal point.

[0021] More specifically, as illustrated in [Fig. 4], photons from a point source (13) passing through a channel (10) of a point-source imager (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 difference in space between the MPO and the image plane Pi so that, on [Fig.4], X=M*x and Y=M*y, with X, Y the frames of the image plane Pi, and x, y the frames of the MPO.

[0022] Thus, rays that do not concentrate towards the focal point contribute to cross-shaped noise and a diffuse background at the level of the image plane, as illustrated in [Fig.5].

[0023] This problem of noise in the form of a cross is widely exposed in the prior art and it is a problem that has not really been solved for many years.

[0024] 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 design of the MPO by adjusting parameters such as the aspect ratio of the channels, the reflectivity of the surfaces and the geometry to limit the effect of cross-shaped noise.

[0025] 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, X-ray focusing with Wolter microchannel plate optics,

[0026] Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Volume 490, Issues 1-2, 2002, Pages 276-289, ISSN 0168-9002.

[0027] In these types of arrangements, a single reflection on a wall of a channel forming a circular element is sought. However, some photons may pass through such a MPO without undergoing any reflection. These photons then contribute to a diffuse background at the image plane.

[0028] Even if it is less intense than in the case of a square configuration, this diffuse background remains too intense for most optical applications.

[0029] In the publication R. Willingale, GW Fraser, and JF Pearson "Opthnization 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.

[0030] The publication R. Willingale, JF Pearson, A. Martindale, CH Feldman, R. Fairbend, E. Schyns, S. Petit, JP Osbome, 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.

[0031] 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 acquiring successive images while rotating the MPO to smooth out 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.

[0032] The publication 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.

[0033] The publication Songwu Peng, Fei Wei, Yihong Guo, Yizhong Ye, “Preliminary geometry parameters optimization of lobster-eye-type wide field of view soft x-ray imager,” Opt. Eng. 58(9), 093101 (2019) analyzes the channel radius curvature errors to limit the effect of cross-shaped noise.

[0034] 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.

[0035] 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.

[0036] In conclusion, although the prior 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 reducing it significantly.

[0037] 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, prior art solutions are insufficient, typically for imaging applications. and X-ray analysis, such as X-ray diffraction or X-ray fluorescence spectroscopy.

[0038] 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. Description of the invention

[0039] 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 of the noise area to be reduced on the image plane.

[0040] Moreover, 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.

[0041] Thus, according to a first aspect, the invention relates to a micro-pore optics 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 optics 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 zone of said micropore optics, the area of ​​said central zone being determined as a function of a noise zone area to be reduced on the image plane, and the distance between the image plane and said micropore optics.

[0042] Shuttering the central area thus reduces the noise present around the spot. This shuttering is particularly effective when the matrix has a circular arrangement. In this embodiment, the individual pixels of the matrix are circular and arranged regularly in a concentric pattern. With a circular arrangement, the pixel or pixels that constitute the shuttered area include at least one circular region centered on the center of the matrix.

[0043] When the micro-pore optics have a square arrangement, the obturation zone is preferably 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 vertical arm of the cross, while the horizontal band allows to limit the photons contributing to the horizontal arm of the cross. To define the width of each band, it suffices to consider the thickness of the cross naturally formed on a MPO without a shutter zone, defining the noise area to be reduced on the image plane, and to apply the ratio M described in relation to [Fig. 4] of the prior art. In addition, the two orthogonal bands of the shutter zone limit the photons that contribute to the diffuse background noise around the spot.

[0045] It may be advantageous to opacify, as an alternative 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 [Fig. 4] of the prior art.Thus, each channel for which the product x*y 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 product x*y. Such a blocking therefore limits the noisy photons in a region around the spot, and further reduces the noise level beyond it, with a very limited impact on the flux reaching the spot.

[0046] Furthermore, said source can be positioned on the focal plane of said micro-pore optics so as to provide a collimated beam.

[0047] In a collimation application, typically for X-ray imaging and analysis applications, the presence of bands centered on the width and length of said micro-pore optics suppresses noise photons having a divergence in the vertical plane and in the horizontal plane less than 1 / 2*A / Ls, with Ls corresponding to the distance between the source and the MPO as illustrated in [Fig.4] of the prior art, where A is the dimension of the obturated area.

[0048] Alternatively, the position of said source with respect to said micro-pore optics and its focal plane can be chosen so as to produce a focused beam.

[0049] For certain applications, micro-pore optics may also have a positive or negative radius of curvature along an optical axis.

[0050] According to a first embodiment, the obturation zone is formed 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 formed by both the obturation plate and the various mini-MPOs.

[0051] 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 attaching the obturation plate.

[0052] In both of these embodiments, the sealing plate can be made of lead or any other material opaque to X-rays.

[0053] In the second embodiment, the sealing plate can be printed on a film deposited on said micro-porous optics or printed directly on said micro-porous optics.

[0054] 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 therefore obturated by apodization, that is to say, a structural modification of the channels in the obturation zone, carried out before or after the formation of the matrix, so that the apodized channels are opaque to X-rays.

[0055] 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 produce said channels forming said sealing area of ​​the matrix.

[0056] It is also possible to modify the conventional manufacturing process for forming the obturated channels. To do this, the process may include the following steps: manufacturing 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.

[0057] In this channel fabrication process, it is possible to use several successive stretchings and assemblies of the transmission and obturation fibers, or to apply special treatments to the MPOs, such as treatments aimed at controlling the roughness of the open channels.

[0058] To do this, it is possible to deposit a metallization inside the channels or to use a glass forming technique which consists of heating the channels until they become soft enough to conform to the shape of a mold, a technique also known by the term "slumping" in Anglo-Saxon literature.

[0059] According to another aspect, the invention also relates to an X-ray imaging system for a sample, comprising: an X-ray source configured to illuminate said sample through micro-pore optics according to the first aspect of the invention; and a detector placed on a plane of reflection of the rays emanating from said sample.

[0060] Alternatively, the X-ray imaging system of a sample comprises: an X-ray source configured to illuminate said sample; a micro-pore optic according to the first aspect of the invention; and a detector placed on the image plane of said micro-pore optic, said micro-pore optic being configured to collect photons from the sample and transmit them to the detector.

[0061] To improve the performance of the micropore optics, a mask can be used after said micropore optics. This mask thus complements the blocking of noise photons in the area of ​​the image plane where "cross noise" photons arrive, that is, in the part of the image plane that is not protected from this noise by the blocking of the channels.

[0062] Summary description of the figures

[0063] The manner in which the invention can be implemented and the resulting advantages will be more apparent from the following embodiment examples, given by way of illustration and not limitation, in support of the attached figures.

[0064] [Fig. 1] The [Fig. 1] is a perspective view of the channels of a prior art micro-pore optic;

[0065] [Fig.2] Fig.2 illustrates a cross-sectional view of the channels of the micro-pore optics of the [Fig.l] which contribute to part of the cross noise;

[0066] [Fig.3] Fig.3 illustrates perspective views of possible reflections at the interior of a state-of-the-art micro-pore optic;

[0067] [Fig.4] Figure [Fig.4] illustrates the dispersions between a source and a micro-pore optic and an image plan according to the state of the art;

[0068] [Fig. 5] Figure 5 illustrates the image plane of a micro-pore optics of the state of the technique;

[0069] [Fig. 6] Figure 6 illustrates the image plane obtained with a micro-pore optic according to an embodiment of the invention;

[0070] [Fig. 7] Figure 7 illustrates a top view of a micro-pore optic according to a first embodiment of the invention;

[0071] [Fig-8] Fig. 8 illustrates a top view of a micro-pore optic according to a second embodiment of the invention;

[0072] [Fig.9] Fig.9 illustrates a top view of a micro-pore optic according to a third implementation of the invention;

[0073] [Fig. 10] Fig. 10 illustrates a top view of a micro-pore optic according to a fourth implementation of the invention;

[0074] [Fig. 11] Fig. 11 illustrates a cross-sectional view of a micro-pore optic according to a embodiment of the invention having a first radius of curvature;

[0075] [Fig. 12] Fig. 12 illustrates a cross-sectional view of a micro-pore optic according to a embodiment of the invention having a second radius of curvature;

[0076] [Fig. 13] The [Fig. 13] illustrates a schematic representation of a first system X-ray imaging of a sample incorporating micro-pore optics according to the invention; and

[0077] [Fig. 14] Figure 14 illustrates a schematic representation of a second system X-ray imaging of a sample incorporating a micro-pore optic according to the invention. Detailed description of the invention

[0078] As illustrated in Figures 7 to 10, the invention therefore 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 micropore optic, particularly when the micropore optic has a circular arrangement. In addition to the obturation 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 micro-pore optic.

[0079] 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 to 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, the cross noise therefore requires the preferential use of a blocking zone in the form of two orthogonal bands. These orthogonal bands are illustrated in [Fig. 7] with two bands in which the channels are blocked. Alternatively or in addition to these two bands, it is It is also possible to use a cross with hyperbolic contours, as illustrated in [Fig.8].

[0080] The cross with a straight or hyperbolic contour can be obtained with apodized channels (21). The apodization of these channels corresponds to a sealing so that these channels are opaque to X-rays. To do this, it is possible to produce the matrix of the micro-pore optics with three-dimensional printing, in which the printing pattern incorporates only open channels (10) in the areas for which the channels do not need to be apodized.

[0081] Alternatively, it is possible to carry out the apodization after the micro-pore optics have been made, for example by bringing a lead obturation plate over the desired obturation area.

[0082] Furthermore, it is also possible to fabricate the micropore optics by modifying the conventional fabrication process to position the apodized channels (21) at the desired locations. To this end, the fabrication of the micropore optics fibers conventionally involves steps of fabricating transmission fibers with a core soluble in an acid and a cladding surrounding the core insoluble in the same acid, followed by steps of assembling and drawing these fibers to obtain transmission fibers with a predetermined diameter.

[0083] 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 fibers and the sealing fibers can be assembled in the desired pattern to form the matrix (23), as illustrated in the embodiments of Figures 7 or 8.

[0084] Following this assembly phase, the assembly can be cut transversely to a desired thickness to form a base wafer, before implementing a conventional step in which a chemical etch of the base wafer opens the transmission fiber channels. After this chemical etch process, the resulting MPO can therefore be an MPO with sealing fibers forming the apodized channels (21), as illustrated in Figures 7 or 8.

[0085] As an alternative to this method, it is also possible to attach mini-MPOs (25) around a sealing plate (24) forming the sealing area, as illustrated in Figures 9 or 10. In these embodiments, a cross-shaped sealing 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 of [Fig. 9], one mini-MPO is positioned at each corner of the matrix (23), whereas in the embodiment of [Fig. 10], four mini-MPOs (25) are positioned in each corner of the matrix (23). Alternatively, each corner of the matrix could also incorporate 9 or more mini-MPOs (25).

[0086] 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.

[0087] In addition to the apodization or obturation performed on certain parts of the matrix (23) of the MPO, 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 particularly, in [Fig. 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 [Fig. 12], the micropore 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 reduced area of ​​the image plane Pi.

[0088] The invention thus finds a particularly advantageous application for limiting noise in systems using a MPO. Indeed, as illustrated in [Fig. 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.

[0089] This noise limitation opens up new applications for MPOs where noise is currently a discriminating 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 [Fig. 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).

[0090] As an alternative to the X-ray imaging system illustrated in [Fig.13], it is also possible to place the MPO between the X-ray source (17) and the sample (16), the detector (12) directly capturing the intensity of the point reflected by the sample (16) as illustrated in [Fig. 14].

[0091] In addition, it is also possible to place a mask between the MPO micropore optics and the detector, so as to mask part of the image plane and further limit the noise measured on it.

[0092] In conclusion, the invention proposes to apodize or opacify certain parts of a micropore optics matrix 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 allows to consider a large number of new applications, including X-ray analysis of samples.

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 beam of X-rays, 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 shutter zone in which the matrix (23) is opaque to X-rays, said shutter zone being disposed at least in a central zone of said micro-pore optics (MPO), the area of ​​said central zone being determined as a function of a noise zone area to be reduced on the image plane (Pi), and the distance (F) between the image plane (Pi) and said micro-pore optics (MPO).

2. Micro-pore optics (MPO) according to claim 1, wherein said 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 said 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 portion 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: producing transmission fibers with a core soluble in an acid and a sheath surrounding the core insoluble in the same acid; producing sealing fibers with a core and a sheath surrounding the core insoluble in said acid; assembling the transmission fibers with the sealing fibers so that said sealing fibers are arranged at least in a central area of ​​said micropore optic (MPO); cross-cutting the assembly to a desired thickness to form a base wafer; and chemically etching the base wafer so as to open only the channels of the transmission fibers.

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 of a sample (16), comprising: an X-ray source (13, 17) configured to illuminate said sample (16) through a micro-pore optic (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 (16).

13. X-ray imaging system of a sample (16), comprising: an X-ray source (13, 17) configured to illuminate said sample (16); a micro-pore optic (MPO) according to any one of claims 1 to 9; and a detector (12) placed on the image plane (Pi) of said micro-pore optic (MPO), said micro-pore optic (MPO) being configured to collect photons from the sample (16) for transmission 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 portion of the image plane (Pi) at the level of said detector (12).

Images