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25 results on '"Sanli, Umut T."'

1. Single-frame far-field diffractive imaging with randomized illumination

Author

Levitan, Abraham L., Keskinbora, Kahraman, Sanli, Umut T., Weigand, Markus, and Comin, Riccardo

Subjects
Physics - Optics, Condensed Matter - Materials Science, Electrical Engineering and Systems Science - Image and Video Processing
Abstract

We introduce a single-frame diffractive imaging method called randomized probe imaging (RPI). In RPI, a sample is illuminated by a structured probe field containing speckles smaller than the sample's typical feature size. Quantitative amplitude and phase images are then reconstructed from the resulting far-field diffraction pattern. The experimental geometry of RPI is straightforward to implement, requires no near-field optics, and is applicable to extended samples. When the resulting data are analyzed with a complimentary algorithm, reliable reconstructions which are robust to missing data are achieved. To realize these benefits, a resolution limit associated with the numerical aperture of the probe-forming optics is imposed. RPI therefore offers an attractive modality for quantitative X-ray phase imaging when temporal resolution and reliability are critical but spatial resolution in the tens of nanometers is sufficient. We discuss the method, introduce a reconstruction algorithm, and present two proof-of-concept experiments: one using visible light, and one using soft X-rays.

Published
2020
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2. Apochromatic X-ray focusing

Author

Sanli, Umut T., Rodgers, Griffin, Zdora, Marie-Christine, Qi, Peng, Garrevoet, Jan, Falch, Ken Vidar, Müller, Bert, David, Christian, and Vila-Comamala, Joan

Published
2023
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6. NFFA-Europe Pilot - D12.1 - Fabrication of hard X-ray aberration correctors

Author

Vila-Comamala, Joan, Seiboth, Frank, Qi, Peng, Sanli, Umut T., and David, Christian

Abstract

We report on the fabrication of hard X-ray aberration correctors to improve the performance of nanofocusing X-ray lenses by correcting the shape deviations that arise due to fluctuations and anisotropies during the manufacture of X-ray optics. After carefully characterizing the aberrations of the focusing X-ray lens, the tailored profile of a correction phase plate can be inferred. In this deliverable, we have developed the micro and nanofabrication processes for the production of the refractive phase plates by two-photon polymerization based 3D printing. The refractive phase plate is made of polymer, which introduces the required phase shift corrections while hardly introducing any extra absorption. The process parameters have been optimized to obtain the tailored aberration correction profiles. The refractive phase plates have been produced on multiple substrates such as silicon, silicon nitride and diamond membranes and they can be fabricated reliably and on-demand. The methods and procedures to easily align the focusing optics and the refractive phase plate are currently under development., WP12 - X-ray Wavefront Metrology, Correction and Manipulation

Published
2022
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9. Single-frame far-field diffractive imaging with randomized illumination

Author

Massachusetts Institute of Technology. Department of Physics, Levitan, Abraham, Keskinbora, Kahraman, Sanli, Umut T., Weigand, Markus, Comin, Riccardo, Massachusetts Institute of Technology. Department of Physics, Levitan, Abraham, Keskinbora, Kahraman, Sanli, Umut T., Weigand, Markus, and Comin, Riccardo

Abstract

We introduce a single-frame diffractive imaging method called randomized probe imaging (RPI). In RPI, a sample is illuminated by a structured probe field containing speckles smaller than the sample’s typical feature size. Quantitative amplitude and phase images are then reconstructed from the resulting far-field diffraction pattern. The experimental geometry of RPI is straightforward to implement, requires no near-field optics, and is applicable to extended samples. When the resulting data are analyzed with a complimentary algorithm, reliable reconstructions which are robust to missing data are achieved. To realize these benefits, a resolution limit associated with the numerical aperture of the probe-forming optics is imposed. RPI therefore offers an attractive modality for quantitative X-ray phase imaging when temporal resolution and reliability are critical but spatial resolution in the tens of nanometers is sufficient. We discuss the method, introduce a reconstruction algorithm, and present two proof-of-concept experiments: one using visible light, and one using soft X-rays., National Science Foundation (Grants 1751739, DMR-1231319), Department of Energy, Office of Science (DE-SC0019126)

Published
2020

10. Building Blocks for Magnon Optics: Emission and Conversion of Short Spin Waves

Author

Groß, Felix, primary, Zelent, Mateusz, additional, Träger, Nick, additional, Förster, Johannes, additional, Sanli, Umut T., additional, Sauter, Robert, additional, Decker, Martin, additional, Back, Christian H., additional, Weigand, Markus, additional, Keskinbora, Kahraman, additional, Schütz, Gisela, additional, Krawczyk, Maciej, additional, and Gräfe, Joachim, additional

Published
2020
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14. In SituX-ray Diffraction and Spectro-Microscopic Study of ALD Protected Copper Films

Author

Dogan, Gül, Sanli, Umut T., Hahn, Kersten, Müller, Lutz, Gruhn, Herbert, Silber, Christian, Schütz, Gisela, Grévent, Corinne, and Keskinbora, Kahraman

Abstract

In many applications of copper in industry and research, copper migration and degradation of metallic copper to its oxides is a common problem. There are numerous ways to overcome this degradation with varying success. Atomic layer deposition (ALD) based encapsulation and passivation of the metallic copper recently emerged as a serious route to success owing to the conformality and density of the ALD films. So far, the majority of the studies have been focused on corrosion protection of copper in a variety of chemical environments, mostly at ambient temperature. An investigation of the stability of the ALD film stacks and copper’s interaction with them at elevated temperatures has been lacking. Here, we study the mitigation of copper oxidation and migration in 50 nm thick Al2O3/TiO2and Al2O3/SiO2bilayer ALD stacks. First, the corrosion dynamics were investigated via in situX-ray diffraction (XRD) at 350 °C under atmospheric conditions, and second, the interaction of copper with the passivation layers have been examined post factumusing detailed spectro-microscopic investigations. According to the XRD results, both ALD films exhibited excellent oxidation protection. In contrast, bare Cu immediately started to oxidize at 350 °C and transformed entirely to its known oxide phases in 4 h. Spectro-microscopic studies revealed that there are structural and chemical changes on the top surface and within the film stacks. The TiO2layer was crystallized during annealing, while the SiO2layer stayed in the amorphous phase, which was analyzed by grazing incidence XRD and transmission electron microscopy. According to scanning electron microscopy and X-ray photoelectron spectroscopy analysis, copper was detected on the surface with a higher amount in Al2O3/TiO2than Al2O3/SiO2, 5.2 at.% and 0.7 at.%, respectively. Based on the surface and cross-sectional analysis, copper migration was observed on both layers, albeit more substantially in Al2O3/TiO2. In the case of Al2O3/SiO2, the bulk of the copper was captured at the interface of the two oxides.

Published
2020
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15. Comparative study of ALD SiO2 thin films for optical applications

Author

Pfeiffer, Kristin, Shestaeva, Svetlana, Bingel, Astrid, Munzert, Peter, Ghazaryan, Lilit, van Helvoirt, C.A.A., Kessels, W.M.M., Sanli, Umut T., Grevent, Corinne, Schütz, G., Putkonen, M., Buchanan, Iain, Jensen, Lars, Ristau, Detlev, Tünnermann, Andreas, Szeghalmi, Adriana, Pfeiffer, Kristin, Shestaeva, Svetlana, Bingel, Astrid, Munzert, Peter, Ghazaryan, Lilit, van Helvoirt, C.A.A., Kessels, W.M.M., Sanli, Umut T., Grevent, Corinne, Schütz, G., Putkonen, M., Buchanan, Iain, Jensen, Lars, Ristau, Detlev, Tünnermann, Andreas, and Szeghalmi, Adriana

Abstract

We have investigated the suitability of atomic layer deposition (ALD) for SiO2 optical coatings and applied it to broadband antireflective multilayers in combination with HfO2 as the high refractive index material. SiO2 thin films were successfully grown using tris[dimethylamino]silane (3DMAS), bis[diethylamino]silane (BDEAS) with plasma activated oxygen as precursors, and the AP-LTO330 precursor with ozone, respectively. The amorphous SiO2 films show very low optical losses within a spectral range of 200 nm to 1100 nm. Laser calorimetric measurements show absorption losses of 300 nm thick SiO2 films of about 1.5 parts per million at a wavelength of 1064 nm. The films are optically homogeneous and possess a good scalability of film thickness. The film surface porosity - which correlates to a shift in the transmittance spectra under vacuum and air conditions - has been suppressed by optimized plasma parameters or Al2O3 sealing layers.

Published
2016

16. Multilayer Fresnel zone plates for high energy radiation resolve 21 nm features at 1.2 keV

Author

Keskinbora, Kahraman, Robisch, Anna-Lena, Mayer, Marcel, Sanli, Umut T., Grévent, Corinne, Wolter, Christian, Weigand, Markus, Szeghalmi, Adriana, Knez, Mato, Salditt, Tim, and Schütz, Gisela

Subjects
X-ray microscopy, extreme ultraviolet, Diffractive lenses
Abstract

X-ray microscopy is a successful technique with applications in several key fields. Fresnel zone plates (FZPs) have been the optical elements driving its success, especially in the soft X-ray range. However, focusing of hard X-rays via FZPs remains a challenge. It is demonstrated here, that two multilayer type FZPs, delivered from the same multilayer deposit, focus both hard and soft X-rays with high fidelity. The results prove that these lenses can achieve at least 21 nm half-pitch resolution at 1.2 keV demonstrated by direct imaging, and sub-30 nm FWHM (full-pitch) resolution at 7.9 keV, deduced from autocorrelation analysis. Reported FZPs had more than 10% diffraction efficiency near 1.5 keV. peerReviewed

Published
2014

18. Comparative study of ALD SiO_2 thin films for optical applications

Author

Pfeiffer, Kristin, primary, Shestaeva, Svetlana, additional, Bingel, Astrid, additional, Munzert, Peter, additional, Ghazaryan, Lilit, additional, van Helvoirt, Cristian, additional, Kessels, Wilhelmus M. M., additional, Sanli, Umut T., additional, Grévent, Corinne, additional, Schütz, Gisela, additional, Putkonen, Matti, additional, Buchanan, Iain, additional, Jensen, Lars, additional, Ristau, Detlev, additional, Tünnermann, Andreas, additional, and Szeghalmi, Adriana, additional

Published
2016
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