Sub-micron focusing of soft x-ray free electron laser beam

Bajt, Saša; Chapman, Henry N.; Nelson, A. J.; Lee, R. W.; Toleikis, S.; Mirkarimi, Paul B.; Alameda, Jennifer B.; Baker, Sherry L.; Vollmer, Hubert; Graff, R. T.; Aquila, Andrew; Gullikson, Eric M.; Ilse, J. Meyer; Spiller, Eberhard; Krzywiński, J.; Juha, L.; Chalupský, J.; Hájková, V.; Hajdu, János; Tschentscher, Th.

doi:10.1117/12.822498

Cited by 11 publications

(8 citation statements)

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“…11 To examine capabilities and limitations of the in situ beam profile characterization by using diagnostics port and ablative imprints technique, a comparison between in situ and ex situ measurements was done. For the sake of comparison, the imprints taken at FLASH earlier (in 2009) during an experiment with a super-polished off-axis parabolic mirror 12,13 were re-used. Goal of this former experiment was to achieve a sub-micrometer focus at wavelength of 13.5 nm.…”

Section: Ablative Imprints and Comparison With Ex Situ Measurementsmentioning

confidence: 99%

In situ focus characterization by ablation technique to enable optics alignment at an XUV FEL source

Gerasimova

Dziarzhytski

Weigelt

et al. 2013

Review of Scientific Instruments

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In situ focus characterization is demonstrated by working at an extreme ultraviolet (XUV) free-electron laser source using ablation technique. Design of the instrument reported here allows reaching a few micrometres resolution along with keeping the ultrahigh vacuum conditions and ensures high-contrast visibility of ablative imprints on optically transparent samples, e.g., PMMA. This enables on-line monitoring of the beam profile changes and thus makes possible in situ alignment of the XUV focusing optics. A good agreement between focal characterizations retrieved from in situ inspection of ablative imprints contours and from well-established accurate ex situ analysis with Nomarski microscope has been observed for a typical micro-focus experiment.

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Section: Ablative Imprints and Comparison With Ex Situ Measurementsmentioning

confidence: 99%

In situ focus characterization by ablation technique to enable optics alignment at an XUV FEL source

Gerasimova

Dziarzhytski

Weigelt

et al. 2013

Review of Scientific Instruments

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“…In the experimental chamber at BL3, an off-axis parabolic mirror coated with a Si/Mo multilayer for 13.5 nm was incorporated, allowing us to tightly focus the beam on a submicron spot (Bajt et al, 2009). The parabola has a focal length of 269 mm, and the smallest focal spot was usually 1 μm in diameter.…”

Section: The Free-electron Laser Flashmentioning

confidence: 99%

XUV spectroscopic characterization of warm dense aluminum plasmas generated by the free-electron-laser FLASH

et al. 2012

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We report on experiments aimed at the generation and characterization of solid density plasmas at the free-electron laser FLASH in Hamburg. Aluminum samples were irradiated with XUV pulses at 13.5 nm wavelength (92 eV photon energy). The pulses with duration of a few tens of femtoseconds and pulse energy up to 100 μJ are focused to intensities ranging between 10 13 and 10 17 W/cm 2 . We investigate the absorption and temporal evolution of the sample under irradiation by use of XUV and optical spectroscopy. We discuss the origin of saturable absorption, radiative decay, bremsstrahlung and atomic and ionic line emission. Our experimental results are in good agreement with simulations.

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“…We previously demonstrated that such multilayer-coated optics survives the beam if it is placed in a defocused position [23]. However, we also observed that in poor vacuum the optic's reflectivity decreases with time due to carbon contamination [24]. Investigations of different materials close to their damage thresholds showed similar damage as materials and multilayers show when exposed to high temperatures.…”

Section: Introductionmentioning

confidence: 62%

Thermal stability studies of short period Sc/Cr and Sc/B₄C/Cr multilayers

et al. 2014

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The stability of short period Sc/Cr and Sc/B₄C/Cr multilayers was investigated over a large temperature range. The aim was to find a stable reflective coating for an off-axis parabola for focusing x rays from a soft x-ray free-electron laser. Normal incidence reflectivity, surface roughness, and intrinsic stress were investigated as a function of annealing temperature and two samples were also studied with a high-resolution transmission electron microscope (TEM), a scanning TEM, and through electron energy loss spectroscopy (EELS). Interface-engineered Sc/B₄C/Cr multilayers showed increased thermal stability and higher reflectivity as compared to pure Sc/Cr multilayers.

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Sub-micron focusing of soft x-ray free electron laser beam

Cited by 11 publications

References 1 publication

In situ focus characterization by ablation technique to enable optics alignment at an XUV FEL source

In situ focus characterization by ablation technique to enable optics alignment at an XUV FEL source

XUV spectroscopic characterization of warm dense aluminum plasmas generated by the free-electron-laser FLASH

Thermal stability studies of short period Sc/Cr and Sc/B₄C/Cr multilayers

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Sub-micron focusing of soft x-ray free electron laser beam

Cited by 11 publications

References 1 publication

In situ focus characterization by ablation technique to enable optics alignment at an XUV FEL source

In situ focus characterization by ablation technique to enable optics alignment at an XUV FEL source

XUV spectroscopic characterization of warm dense aluminum plasmas generated by the free-electron-laser FLASH

Thermal stability studies of short period Sc/Cr and Sc/B4C/Cr multilayers

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Thermal stability studies of short period Sc/Cr and Sc/B₄C/Cr multilayers