TY  - JOUR
A1  - Dittmann, Jonas
A1  - Balles, Andreas
A1  - Zabler, Simon
T1  - Optimization based evaluation of grating interferometric phase stepping series and analysis of mechanical setup instabilities
JF  - Journal of Imaging
N2  - The diffraction contrast modalities accessible by X-ray grating interferometers are not imaged directly but have to be inferred from sine-like signal variations occurring in a series of images acquired at varying relative positions of the interferometer’s gratings. The absolute spatial translations involved in the acquisition of these phase stepping series usually lie in the range of only a few hundred nanometers, wherefore positioning errors as small as 10 nm will already translate into signal uncertainties of 1–10% in the final images if not accounted for. Classically, the relative grating positions in the phase stepping series are considered input parameters to the analysis and are, for the Fast Fourier Transform that is typically employed, required to be equidistantly distributed over multiples of the gratings’ period. In the following, a fast converging optimization scheme is presented simultaneously determining the phase stepping curves’ parameters as well as the actually performed motions of the stepped grating, including also erroneous rotational motions which are commonly neglected. While the correction of solely the translational errors along the stepping direction is found to be sufficient with regard to the reduction of image artifacts, the possibility to also detect minute rotations about all axes proves to be a valuable tool for system calibration and monitoring. The simplicity of the provided algorithm, in particular when only considering translational errors, makes it well suitable as a standard evaluation procedure also for large image series.
KW  - X-ray imaging
KW  - Talbot–Lau interferometer
KW  - grating interferometer
KW  - phase contrast imaging
KW  - darkfield imaging
KW  - phase stepping
KW  - optimization
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-197723
SN  - 2313-433X
VL  - 4
IS  - 6
ER  - 
TY  - JOUR
A1  - Opolka, Alexander
A1  - Müller, Dominik
A1  - Fella, Christian
A1  - Balles, Andreas
A1  - Mohr, Jürgen
A1  - Last, Arndt
T1  - Multi-lens array full-field X-ray microscopy
JF  - Applied Sciences
N2  - X-ray full-field microscopy at laboratory sources for photon energies above 10 keV suffers from either long exposure times or low resolution. The photon flux is mainly limited by the objectives used, having a limited numerical aperture NA. We show that this can be overcome by making use of the cone-beam illumination of laboratory sources by imaging the same field of view (FoV) several times under slightly different angles using an array of X-ray lenses. Using this technique, the exposure time can be reduced drastically without any loss in terms of resolution. A proof-of-principle is given using an existing laboratory metal-jet source at the 9.25 keV Ga K\(_α\)-line and compared to a ray-tracing simulation of the setup.
KW  - X-ray microscopy
KW  - full-field microscopy
KW  - compound refractive X-ray lenses
KW  - CRLs
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-244974
SN  - 2076-3417
VL  - 11
IS  - 16
ER  - 
TY  - JOUR
A1  - Müller, Dominik
A1  - Graetz, Jonas
A1  - Balles, Andreas
A1  - Stier, Simon
A1  - Hanke, Randolf
A1  - Fella, Christian
T1  - Laboratory-Based Nano-Computed Tomography and Examples of Its Application in the Field of Materials Research
JF  - Crystals
N2  - In a comprehensive study, we demonstrate the performance and typical application scenarios for laboratory-based nano-computed tomography in materials research on various samples. Specifically, we focus on a projection magnification system with a nano focus source. The imaging resolution is quantified with common 2D test structures and validated in 3D applications by means of the Fourier Shell Correlation. As representative application examples from nowadays material research, we show metallization processes in multilayer integrated circuits, aging in lithium battery electrodes, and volumetric of metallic sub-micrometer fillers of composites. Thus, the laboratory system provides the unique possibility to image non-destructively structures in the range of 170–190 nanometers, even for high-density materials.
KW  - nano CT
KW  - laboratory
KW  - X-ray
KW  - 3D reconstruction
KW  - instrumentation
KW  - integrated circuits
KW  - nondestructive testing
KW  - 3D X-ray microscopy
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-241048
SN  - 2073-4352
VL  - 11
IS  - 6
ER  -