X-ray ptychography in 3D is ideal for quantitative structural analysis with highest spatial resolution. The Ptychographic Nano-Analytical Microscope (PtyNAMi) installed at beamline P06 at PETRA III (DESY, Hamburg) is optimized for high-resolution scanning hard X-ray microscopy. The current data evaluation pipeline for ptychographic tomography at PtyNAMi is outlined and the performance of the microscope demonstrated at the example of an inverse opal Ni sample.
Scanning coherent X-ray microscopy (ptychography) has gained considerable interest during the last decade since the performance of this indirect imaging technique does not necessarily rely on the quality of the X-ray optics and, in principle, can achieve highest spatial resolution in X-ray imaging. The method can be easily extended to 3D by adding standard tomographic reconstruction schemes. However, the tomographic reconstruction is often applied in a subsequent step using a sequence of aligned ptychographic 2D projections. In this contribution, we outline current developments of a GPU-accelerated framework for direct 3D ptychography, coupling 2D ptychography and tomography. The program utilizes a custom GPU-accelerated framework for ptychography that offers three distinct ptychographic reconstruction algorithms. The tomographic reconstruction runs simultaneously and uses numerical routines of the ASTRA Toolbox. This parallel-computing approach results in a high performance increase considerably reducing the reconstruction time of 3D ptychographic datasets.
While modern x-ray microscopes at synchrotron radiation sources and free-electron lasers require x-ray optics of highest quality, these optics often show aberrations due to limitations in fabrication technology. Based on ptychography, we determine these aberrations and fabricate tailor made refractive phase plates to compensate for them. Starting from the aberrated optics, diffraction-limited beams can be generated by introducing the phase plate behind these optics. In addition, the wavefront can be modified to generate custom beams for special needs, such as donut-shaped beams with orbital angular momentum or for structured-illumination microscopy. The nanofocused beam can be engineered in shape and phase by introducing specially designed phase plates. We introduce a general scheme for wavefront engineering and illustrate it with a numerical example.
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