Development of pixel super-resolution scanning transmission X-ray microscopy for material science

Die Entwicklung hochwertiger fokussierender Röntgenoptiken in den letzten Jahrzehnten hat die Transmissionsmikroskopie mit Röntgenstrahlung aus Synchrotronquellen ermöglicht. Proben lassen sich mit extrem hoher Ortsauflösung untersuchen, allerdings einerseits auf Kosten der Bildfeldgröße (bis zu 100 µm x 100 µm) und andererseits bei eingeschränktem Photonenenergiebereich (unter 20 keV), was den Einsatzbereich insbesondere in den Materialwissenschaften erheblich einschränkt. In dieser Arbeit für den Bereich harter Röntgenstrahlung (17-35 keV) die so genannte rasternde superpixelauflösende Röntgentransmissionsmikroskopie entwickelt. Sie ermöglicht es, das Bildfeld zu vergrößern und zugleich die Scanzeit drastisch zu reduzieren, indem die Probe mit einem durch refraktive bikonkav-parabolische Multilinsen erzeugten Feld aus Fokuspunkten abge-rastert wird. Die hochauflösenden Bilder haben eine räumliche Auflösung, in der Größenordnung der Röntgenfokusdurchmesser, und zwar auch wenn die Pixelgröße des zur Datenerfassung eingesetzten Bilddetektors viel größer ist als die Fokusgröße. Da das Schlüsselelement der Technik eine Röntgenoptik ist, werden die Entwicklung und Herstellung einer (zwei)-dimensionalen brechenden Multilinse zur Fokussierung hochenergetischer Röntgenstrahlung vorgestellt, die mit Hilfe von Röntgentiefenlithographie und Galvanik hergestellt wurde. Es werden die Röntgencharakterisierung dieser Optiken und Mikroskopieexperimente vorgestellt, die an den Synchrotronquellen KARA (Deutschland), Diamond Light Source (England) und SPring-8 (Japan) durchgeführt wurden. Da die Höhe der herkömmlichen refraktiven Multilinsen das Sichtfeld immer noch einschränkt (bestenfalls im Millimeterbereich), wurde eine Treppenanordnung aus zum Substrat geneigten RMLs entwickelt, die eine pixel-superauflösende Rasterröntgenmikroskopie mit einem Bildfeld von 1.64 cm × 1.64 cm bei einer Auflösung von 780 ± 40 nm unter Verwendung von 35 keV Röntgenstrahlung ermöglicht. Die Scanzeit betrug nur etwa vier Minuten. Die einzigartigen Möglichkeiten der rasternden superpixelauf-lösenden Röntgentransmissionsmikroskopie mit harter Röntgenstrahlung wurde durch die Abbildung eines durch selektives Laserschmelzen aus Ti-6Al-4V hergestellten biomedizinischen Implantat-Abutments demonstriert. So wurde die Untersuchung ausgedehnter und dicker Proben für die Materialwissenschaften demonstriert

Development of an Array of Compound Refractive Lenses for Sub-Pixel Resolution, Large Field of View, and Time-Saving in Scanning Hard X-ray Microscopy

A two-dimensional array of compound refractive lenses (2D array of CRLs) designed for hard X-ray imaging with a 3.5 mm$^{2}$ large field of view is presented. The array of CRLs consists of 2D polymer biconcave parabolic 34 × 34 multi-lenses fabricated via deep X-ray lithography. The developed refractive multi-lens array was applied for sub-pixel resolution scanning transmission X–ray microscopy; a raster scan with only 55 × 55 steps provides a 3.5 megapixel image. The optical element was experimentally characterized at the Diamond Light Source at 34 keV. An array of point foci with a 55 µm period and an average size of ca. 2.1 µm × 3.6 µm was achieved. In comparison with the conventional scanning transmission microscopy using one CRL, sub-pixel resolution scanning transmission hard X-ray microscopy enables a large field of view and short scanning time while keeping the high spatial resolution

Photon shot-noise limited transient absorption soft X-ray spectroscopy at the European XFEL

Femtosecond transient soft X-ray Absorption Spectroscopy (XAS) is a very promising technique that can be employed at X-ray Free Electron Lasers (FELs) to investigate out-of-equilibrium dynamics for material and energy research. Here we present a dedicated setup for soft X-rays available at the Spectroscopy & Coherent Scattering (SCS) instrument at the European X-ray Free Electron Laser (EuXFEL). It consists of a beam-splitting off-axis zone plate (BOZ) used in transmission to create three copies of the incoming beam, which are used to measure the transmitted intensity through the excited and unexcited sample, as well as to monitor the incoming intensity. Since these three intensity signals are detected shot-by-shot and simultaneously, this setup allows normalized shot-by-shot analysis of the transmission. For photon detection, the DSSC imaging detector, which is capable of recording up to 800 images at 4.5 MHz frame rate during the FEL burst, is employed and allows approaching the photon shot-noise limit. We review the setup and its capabilities, as well as the online and offline analysis tools provided to users.Comment: 11 figure

Determination of the weld thickness of turbine for aircraft engine by high-energy X-ray tomography

It is necessary to test the weld thickness of turbine, as it is one of the most important parts for aircraft engine. The weld thickness of turbine for aircraft engine by high-energy X-ray tomography was determined. We used an X-ray tube and a betatron as X-ray sources. The wall thickness of two tubes and weld thickness of turbine were measured. It is shown that the high-energy X-ray tomography system is determined the wall thickness of the tube and the weld thickness of turbine with high accuracy. We also studied the method to reduce scattered radiation. All experiments were carried out in the non-destructive testing (NDT) Institute of Tomsk Polytechnic University (TPU)

First results in the development of a mobile robot with trajectory planning and object recognition capabilities

The use of mobile robots is becoming popular in many areas of service because they ensure safety and good performance while working in dangerous or unreachable locations. Areas of application of mobile robots differ from educational research to detection of bombs and their disposal. Based on the mission of the robot they have different configurations and abilities – some of them have additional arms, cranes and other tools, others use sensors and built-in image processing and object recognition systems to perform their missions. The robot that is described in this paper is mobile robot with a turret mounted on top of it. Different approaches have been tested while searching for best method suitable for image processing and template matching goals. Based on the information from image processing unit the system executes appropriate actions for planning motions and trajectory of the mobile robot

Staircase array of inclined refractive multi-lenses for large field of view pixel super-resolution scanning transmission hard X-ray microscopy

Owing to the development of X‐ray focusing optics during the past decades, synchrotron‐based X‐ray microscopy techniques allow the study of specimens with unprecedented spatial resolution, down to 10 nm, using soft and medium X‐ray photon energies, though at the expense of the field of view (FOV). One of the approaches to increase the FOV to square millimetres is raster‐scanning of the specimen using a single nanoprobe; however, this results in a long data acquisition time. This work employs an array of inclined biconcave parabolic refractive multi‐lenses (RMLs), fabricated by deep X‐ray lithography and electroplating to generate a large number of long X‐ray foci. Since the FOV is limited by the pattern height if a single RML is used by impinging X‐rays parallel to the substrate, many RMLs at regular intervals in the orthogonal direction were fabricated by tilted exposure. By inclining the substrate correspondingly to the tilted exposure, 378000 X‐ray line foci were generated with a length in the centimetre range and constant intervals in the sub‐micrometre range. The capability of this new X‐ray focusing device was first confirmed using ray‐tracing simulations and then using synchrotron radiation at BL20B2 of SPring‐8, Japan. Taking account of the fact that the refractive lens is effective for focusing high‐energy X‐rays, the experiment was performed with 35 keV X‐rays. Next, by scanning a specimen through the line foci, this device was used to perform large FOV pixel super‐resolution scanning transmission hard X‐ray microscopy (PSR‐STHXM) with a 780 ± 40 nm spatial resolution within an FOV of 1.64 cm × 1.64 cm (limited by the detector area) and a total scanning time of 4 min. Biomedical implant abutments fabricated via selective laser melting using Ti–6Al–4V medical alloy were measured by PSR‐STHXM, suggesting its unique potential for studying extended and thick specimens. Although the super‐resolution function was realized in one dimension in this study, it can be expanded to two dimensions by aligning a pair of presented devices orthogonally.A new X‐ray focusing device generates hundreds of thousands of line foci, periodically spaced in the sub‐micrometre range, with centimetre length. It enables to achieve large FOV pixel super‐resolution scanning transmission hard X‐ray microscopy. imag