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Matias Kagias

Bio: Matias Kagias is an academic researcher from Paul Scherrer Institute. The author has contributed to research in topics: Scattering & Speckle pattern. The author has an hindex of 1, co-authored 5 publications receiving 8 citations. Previous affiliations of Matias Kagias include California Institute of Technology.

Papers
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Patent
09 Mar 2017
TL;DR: In this article, a method with several options to manufacture high aspect ratio structures is proposed, which is based on fabrication of high aspect-ratio recess structure in silicon by dry or chemical etching and then filling the high aspect ratios recess with metal by using electroplating, atomic layer deposition, wafer bonding, metal casting or combination of these techniques.
Abstract: A method with several options to manufacture high aspect ratio structures is proposed. The method is based on fabrication of high aspect ratio recess structure in silicon by dry or chemical etching and then filling the high aspect ratio recess with metal by using electroplating, atomic layer deposition, wafer bonding, metal casting or combination of these techniques. The gratings can be used for x-ray or neutron imaging, as well as for space applications.

7 citations

Posted ContentDOI
TL;DR: In this paper, simple yet inherently rapid acquisition protocols for X-ray scattering tensor tomography leveraging on these new optical elements are proposed, which are not only rapid but also corroborate that sufficient information for the accurate volumetric reconstruction of the scattering properties is provided.
Abstract: Microstructural information over an entire sample is important to understand the macroscopic behaviour of materials. X-ray scattering tensor tomography facilitates the investigation of the microstructural organisation in statistically large sample volumes. However, established acquisition protocols based on scanning small-angle X-ray scattering and X-ray grating interferometry inherently require long scan times even with highly brilliant X-ray sources. Recent developments in X-ray diffractive optics towards circular pattern arrays enable fast single-shot acquisition of the sample scattering properties with 2D omnidirectional sensitivity. X-ray scattering tensor tomography with the use of this circular grating array has been demonstrated. We propose here simple yet inherently rapid acquisition protocols for X-ray scattering tensor tomography leveraging on these new optical elements. Results from both simulation and experimental data, supported by a null space analysis, suggest that the proposed acquisition protocols are not only rapid but also corroborate that sufficient information for the accurate volumetric reconstruction of the scattering properties is provided. The proposed acquisition protocols will build the basis for rapid inspection and/or time-resolved tensor tomography of the microstructural organisation over an extended field of view.

2 citations

Journal ArticleDOI
TL;DR: In this paper, the use of a speckle pattern in order to retrieve omnidirectional differential phase and dark-field images was investigated and the claim that a simple modulator can have distinct benefits comparted to X-ray optics was found to be inaccurate.
Abstract: The paper by Wang and Sawhney (1) describes the use of a speckle pattern in order to retrieve omnidirectional differential phase and dark-field images. Although the approach is methodologically correct and the claim that a simple modulator can have distinct benefits comparted to X-ray optics is true, there are a few passages in both the significance statement and the main text that we find to be inaccurate. [↵][1]1To whom correspondence may be addressed. Email: mkagias{at}caltech.edu. [1]: #xref-corresp-1-1

1 citations

Patent
31 Jul 2019
TL;DR: In this paper, a new arrangement is proposed that allows simultaneous acquisition of the scattering images in all possible directions in a single shot without the need of high resolution or highly coherence sources.
Abstract: X-ray scattering imaging can provide complementary information about the unresolved microstructures of a sample. The scattering signal can be accessed with various methods based on coherent illumination, which span from self-imaging to speckle scanning. The directional sensitivity of the existing methods is limited to a few directions on the imaging plane and it requires the scanning of the optical components, or the rotation of either the sample or the imaging setup, if the full range of possible scattering directions is desired. Recently such an invention has been presented. However, the method requires a very high resolution and is only applicable to imaging setups where this is possible, such as synchrotron facilities. The present invention discloses a new arrangement that allows the simultaneous acquisition of the scattering images in all possible directions in a single shot without the need of high resolution or highly coherence sources. This is achieved by a specialized optical element and means of recording the generated fringe with sufficient spatial resolution.
Patent
04 Sep 2015
TL;DR: In this paper, the authors proposed a system based exclusively on X-ray phase shifting components, without the use of an absorption grating, or a mask or a high-resolution detector.
Abstract: Since the very first experiments with phase-contrast imaging at synchrotrons, X-ray scientists were quite excited by the potential of this novel approach, as the "holy-grail" of boosting the contrast of soft and radiation sensitive materials under dose-control seemed to be finally at reach. The features of gratings-based interferometry (GI) are well suited for transferring this exciting technology from the exclusive synchrotron's community to a much wider basin of potential users. Particularly for medical applications, the relation between image contrast and dose has triggered tremendous efforts in the development of novel imaging devices. Such systems essentially operate near to the photon-starvation limit to cope with the fundamental dilemma of providing sufficient diagnostic sensitivity and sensibility at an acceptable, as low as reasonably achievable (ALARA) risk for the patient. If a new imaging modality were to be implemented in a clinical environment, it is needless to say that it has to be compliant with the very strict regulatory directives. The present invention proposes a system based exclusively on X-ray phase shifting components, i.e. without the use of an absorption grating, or a mask or a high-resolution detector. The novel approach is applicable at all imaging relevant energies and can be easily scalable to large field of views. The invention solves in one shot most the major limitations so far which were preventing a broad dissemination of phase contrast X-ray imaging on conventional sources.

Cited by
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22 Jan 2023
TL;DR: In this article , partial differential equations are written down and then solved, in a closed-form manner, for several variants of the inverse problem of diffusion field retrieval given suitable intensity images.
Abstract: Unresolved spatially-random microstructure, in an illuminated sample, can lead to position-dependent blur when an image of that sample is formed. For a small propagation distance, between the exit surface of the sample and the entrance surface of a position-sensitive detector, the paraxial approximation implies that the blurring influence of the sample may be modeled using an anomalous-diffusion field. This diffusion field may have a scalar or tensor character, depending on whether the random microstructure has an autocorrelation function that is rotationally isotropic or anisotropic, respectively. Partial differential equations are written down and then solved, in a closed-form manner, for several variants of the inverse problem of diffusion-field retrieval given suitable intensity images. Both uniform-illumination and structured-illumination schemes are considered. Links are made, between the recovered diffusion field and certain statistical properties of the unresolved microstructure. The developed theory -- which may be viewed as a crudely parallel form of small-angle scattering under the Guinier approximation -- is applicable to a range of paraxial radiation and matter fields, such as visible light, x rays, neutrons, and electrons.

2 citations

Patent
27 Sep 2019
TL;DR: In this paper, a method for preparing an X-ray gold transmission grating was presented, which first uses a metal catalytic etching technique to fabricate a silicon grating mask with a large groove depth and a steep and smooth sidewall.
Abstract: The present invention discloses a method for preparing an X-ray gold transmission grating. The method firstly uses a metal catalytic etching technique to fabricate a silicon grating mask with a large groove depth and a steep and smooth sidewall, then electroplates and deposits gold in the silicon grating mask groove, and finally removes the silicon grating mask to obtain the gold transmission grating with the large groove depth and the steep and smooth sidewall.

1 citations

Patent
Koehler Thomas1
13 Mar 2019
TL;DR: In this paper, a photo-resist layer is illuminated with radiation using a mask representing a desired grating structure, which is then etched to remove parts of the photo resist layer, leaving a plurality of trenches that are laterally spaced from one across the surface of the substrate.
Abstract: The present invention relates to a grating for X-ray phase contrast and/or dark-field imaging. It is described to form a photo-resist layer on a surface of a substrate. The photo-resist layer is illuminated with radiation using a mask representing a desired grating structure. The photo-resist layer is etched to remove parts of the photo-resist layer, to leave a plurality of trenches that are laterally spaced from one across the surface of the substrate. A plurality of material layers are formed on the surface of the substrate. Each layer is formed in a trench. A material layer comprises a plurality of materials, wherein the plurality of materials are formed one on top of the other in a direction perpendicular to the surface of the substrate. The plurality of materials comprises at least one material that has a k-edge absorption energy that is higher than the k-edge absorption energy of Gold and the plurality of materials comprises Gold.

1 citations

Patent
Deutinger Andrea1
29 Aug 2019
TL;DR: In this paper, a method for producing a microstructure component, an x-ray device and a micro-structured component from a wafer-like silicon substrate is described.
Abstract: A method for producing a microstructure component, a microstructure component and an x-ray device are disclosed. In the method, a plurality of punctiform injection structures are inserted in a grid in a first substrate direction and a second substrate direction, standing at right angles thereto, into a first surface of a wafer-like silicon substrate. The injection structures are lengthened into drilled holes in the depth direction of the silicon substrate in a first etching step. A second surface of the silicon substrate is then at least partly removed for rear-side opening of the drilled holes in a second etching step and in a third etching step, an etching medium acting anisotropically is poured alternately through the drilled holes from both surfaces of the silicon substrate, so that drilled holes arranged next to one another in the first substrate direction connect to form a column running in the first substrate direction.

1 citations

Journal ArticleDOI
TL;DR: In this article , a direct filtered back-projection method based on algebraic filters was proposed to enable rapid tensor-tomographic reconstructions and is a few orders of magnitude faster compared to established techniques, given the same computational resources.
Abstract: Small-angle x-ray scattering tensor tomography provides three-dimensional information on the unresolved material anisotropic microarchitecture, which can be hundreds of times smaller than an image pixel. We develop a direct filtered back-projection method based on algebraic filters that enables rapid tensor-tomographic reconstructions and is a few orders of magnitude faster compared to established techniques, given the same computational resources. We demonstrate the accuracy of the method on experimental data for a fiber-reinforced material sample. The achieved acceleration may pave the way toward the investigation of multiple large samples as well as rapid control and feedback during in situ tensor-tomographic experiments, opening perspectives for the understanding of the fundamental link between functional material properties and microarchitecture.

1 citations