Hard X-ray wavefront correction via refractive phase plates made by additive and subtractive fabrication techniques

High-quality bi-concave 2D focusing diamond X-ray lenses of apex-radius R = 100 µm produced via laser-ablation and improved via mechanical polishing are presented here. Both for polished and unpolished individual lenses and for stacks of ten lenses, the remaining figure errors determined using X-ray speckle tracking are shown and these results are compared with those of commercial R = 50 µm beryllium lenses that have similar focusing strength and physical aperture. For two stacks of ten diamond lenses (polished and unpolished) and a stack of eleven beryllium lenses, this paper presents measured 2D beam profiles out of focus and wire scans to obtain the beam size in the focal plane. These results are complemented with small-angle X-ray scattering (SAXS) measurements of a polished and an unpolished diamond lens. Again, this is compared with the SAXS of a beryllium lens. The polished X-ray lenses show similar figure errors to commercially available beryllium lenses. While the beam size in the focal plane is comparable to that of the beryllium lenses, the SAXS signal of the polished diamond lenses is considerably lower.

Section: Measurements Of Lens Stacksmentioning

confidence: 84%

“…9 (middle). This is particularly amenable to reduction of the wavefront aberrations via the use of azimuthally symmetric refractive phase plates (Seiboth et al, 2020;Dhamgaye et al, 2020). Fig.…”

Section: Possible Correction Of Figure Errorsmentioning

confidence: 99%

Polished diamond X-ray lenses

Celestre¹,

Antipov²,

Gómez³

et al. 2022

“…In order to improve the photon flux at the focal spot, but at the same time keep the beam size to submicrometer level, we reduced the spherical aberration of the lenses (Celestre et al, 2020;Seiboth et al, 2016) by implementing a customized phase plate downstream from the CRLs. Prior to the phase plate production, a stack of 136 lenses was pre-characterized on the Hard X-ray Micro/Nano-Probe Beamline P06 at PETRA III via ptychography in order to achieve optimal lateral coherence in the horizonal direction at 25.6 keV Seiboth et al, 2020). The calculated radial phase shift compensating for spherical aberrations is shown in Fig.…”

Section: Implementation Of Crls and A Phase Platementioning

confidence: 99%

Sub-micrometer focusing setup for high-pressure crystallography at the Extreme Conditions beamline at PETRA III

Glazyrin¹,

Khandarkhaeva²,

Fedotenko³

et al. 2022

Self Cite

Scientific tasks aimed at decoding and characterizing complex systems and processes at high pressures set new challenges for modern X-ray diffraction instrumentation in terms of X-ray flux, focal spot size and sample positioning. Presented here are new developments at the Extreme Conditions beamline (P02.2, PETRA III, DESY, Germany) that enable considerable improvements in data collection at very high pressures and small scattering volumes. In particular, the focusing of the X-ray beam to the sub-micrometer level is described, and control of the aberrations of the focusing compound refractive lenses is made possible with the implementation of a correcting phase plate. This device provides a significant enhancement of the signal-to-noise ratio by conditioning the beam shape profile at the focal spot. A new sample alignment system with a small sphere of confusion enables single-crystal data collection from grains of micrometer to sub-micrometer dimensions subjected to pressures as high as 200 GPa. The combination of the technical development of the optical path and the sample alignment system contributes to research and gives benefits on various levels, including rapid and accurate diffraction mapping of samples with sub-micrometer resolution at multimegabar pressures.

“…The X-rays were nano-focused by an aberration-corrected CRL (Seiboth et al, 2017;Lengeler et al, 2005) consisting of 50 beryllium lenses with an aperture of 300 mm and a radius of curvature of 50 mm, resulting in a diffraction-limited focus size of 94 nm (Schroer et al, 2001). The aberration correction was achieved via a tailor-made 3D-printed polymer phase-plate (PP) (Seiboth et al, 2020), which is placed at the exit of the CRL. The improvement of image quality is shown in Fig.…”

Section: Figurementioning

confidence: 99%

Single-pulse phase-contrast imaging at free-electron lasers in the hard X-ray regime

Hagemann¹,

Vassholz²,

Hoeppe³

et al. 2021

Self Cite

X-ray free-electron lasers (XFELs) have opened up unprecedented opportunities for time-resolved nano-scale imaging with X-rays. Near-field propagation-based imaging, and in particular near-field holography (NFH) in its high-resolution implementation in cone-beam geometry, can offer full-field views of a specimen's dynamics captured by single XFEL pulses. To exploit this capability, for example in optical-pump/X-ray-probe imaging schemes, the stochastic nature of the self-amplified spontaneous emission pulses, i.e. the dynamics of the beam itself, presents a major challenge. In this work, a concept is presented to address the fluctuating illumination wavefronts by sampling the configuration space of SASE pulses before an actual recording, followed by a principal component analysis. This scheme is implemented at the MID (Materials Imaging and Dynamics) instrument of the European XFEL and time-resolved NFH is performed using aberration-corrected nano-focusing compound refractive lenses. Specifically, the dynamics of a micro-fluidic water-jet, which is commonly used as sample delivery system at XFELs, is imaged. The jet exhibits rich dynamics of droplet formation in the break-up regime. Moreover, pump–probe imaging is demonstrated using an infrared pulsed laser to induce cavitation and explosion of the jet.