Comparing different approaches to characterization of focused X-ray laser beams

Chalupský, J.; Boháček, P.; Hájková, V.; Hau‐Riege, Stefan P.; Heimann, P.; Juha, L.; Krzywiński, J.; Messerschmidt, Marc; Moeller, S.; Nagler, Bob; Rowen, M.; Schlotter, W. F.; Swiggers, Michele; Turner, Joshua J.

doi:10.1016/j.nima.2010.12.040

Cited by 54 publications

(36 citation statements)

References 15 publications

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“…5 Estimates of the crater width were made by measuring the lengths of the damaged surface and then scaling by the incidence angle, as the transverse/perpendicular sizes of the FWHM focal spot size taken at normal incidence are nearly symmetric in both transverse directions. Standard methods were used to determine the fluence thresholds for damage [6][7][8] for the samples, as shown in Figure 4 and Table I. In the case of B 4 C at 12 keV, only a lower bound could be given due to the lack of visible damage.…”

mentioning

confidence: 99%

Fluence thresholds for grazing incidence hard x-ray mirrors

Aquila

Sobierajski

Özkan

et al. 2015

Applied Physics Letters

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X-ray Free Electron Lasers (XFELs) have the potential to contribute to many fields of science and to enable many new avenues of research, in large part due to their orders of magnitude higher peak brilliance than existing and future synchrotrons. To best exploit this peak brilliance, these XFEL beams need to be focused to appropriate spot sizes. However, the survivability of X-ray optical components in these intense, femtosecond radiation conditions is not guaranteed. As mirror optics are routinely used at XFEL facilities, a physical understanding of the interaction between intense X-ray pulses and grazing incidence X-ray optics is desirable. We conducted single shot damage threshold fluence measurements on grazing incidence X-ray optics, with coatings of ruthenium and boron carbide, at the SPring-8 Angstrom compact free electron laser facility using 7 and 12 keV photon energies. The damage threshold dose limits were found to be orders of magnitude higher than would naively be expected. The incorporation of energy transport and dissipation via keV level energetic photoelectrons accounts for the observed damage threshold.

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confidence: 99%

Fluence thresholds for grazing incidence hard x-ray mirrors

Aquila

Sobierajski

Özkan

et al. 2015

Applied Physics Letters

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“…The focal spot was found using a so-called z-scan procedure (Chalupský et al, 2011). During the z-scan a 5 mm-thick photosensitive layer of polymethylmethacrylate (PMMA) is exposed to a FEL beam at various z positions along the beam path.…”

Section: Beam Characterization and Determination Of The Single-shot Dmentioning

confidence: 99%

Experimental study of EUV mirror radiation damage resistance under long-term free-electron laser exposures below the single-shot damage threshold

Makhotkin

Sobierajski

Chalupský

et al. 2018

J Synchrotron Radiat

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Edited by M. Zangrando, IOM-CNR and Elettra-Sincrotrone, ItalyKeywords: free-electron laser induced damage; EUV optics; thin films; FELs.Experimental study of EUV mirror radiation damage resistance under long-term free-electron laser exposures below the single-shot damage threshold The durability of grazing-and normal-incidence optical coatings has been experimentally assessed under free-electron laser irradiation at various numbers of pulses up to 16 million shots and various fluence levels below 10% of the single-shot damage threshold. The experiment was performed at FLASH, the Free-electron LASer in Hamburg, using 13.5 nm extreme UV (EUV) radiation with 100 fs pulse duration. Polycrystalline ruthenium and amorphous carbon 50 nm thin films on silicon substrates were tested at total external reflection angles of 20 and 10 grazing incidence, respectively. Mo/Si periodical multilayer structures were tested in the Bragg reflection condition at 16 off-normal angle of incidence. The exposed areas were analysed post-mortem using differential contrast visible light microscopy, EUV reflectivity mapping and scanning X-ray photoelectron spectroscopy. The analysis revealed that Ru and Mo/Si coatings exposed to the highest dose and fluence level show a few per cent drop in their EUV reflectivity, which is explained by EUV-induced oxidation of the surface.

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“…High brightness laser sources such as a fibre laser or a HPDL produces high temperature during material interaction [36,47]. A fibre laser with high brightness in particular offers a longer depth of field (long focal length), small spot sizes, beam quality and a stable laser beam execution.…”

Section: Significance Of Laser Beam Brightnessmentioning

confidence: 99%

“…The brightness of a laser is more effective in comparison to the laser power intensity or any other parameters singularly. This is because by achieving high brightness high processing temperatures would be generated [47]. The use of high brightness laser for material processing is also advantageous due to its potential for achieving low cost per wattage output [48].…”

Section: Significance Of Laser Beam Brightnessmentioning

confidence: 99%

Understanding laser beam brightness: A review and new prospective in material processing

Shukla

Lawrence

Zhang

2015

Optics & Laser Technology

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a b s t r a c tThis paper details the importance of brightness in relation to laser beams. The 'brightness' of lasers is a term that is generally not given much attention in laser applications or in published literature. With this said, it is theoretically and practically an important parameter in laser-material processing. This study is first of a kind which emphasizes in-depth, the concept of brightness of lasers by firstly reviewing the existing literature and the progress with high brightness laser-material processes. Secondly, the techniques used to enhance the laser beam brightness are also reviewed. In addition, we review the brightness fundamentals and rationalize why brightness of lasers is an important concept. Moreover, an update on the analytical technique to determine brightness using the current empirical equations is also provided. A modified equation to determine the laser beam brightness is introduced thereafter. Furthermore, research studies previously conducted to modify laser design to affect laser beam brightness are also discussed. The paper not only involves a review of the techniques used to improve laser beam brightness but also reviews how bright lasers can be employed to enhance/improve laser process capabilities and cost reduction of the laser assisted processes in manufacturing.

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Comparing different approaches to characterization of focused X-ray laser beams

Cited by 54 publications

References 15 publications

Fluence thresholds for grazing incidence hard x-ray mirrors

Fluence thresholds for grazing incidence hard x-ray mirrors

Experimental study of EUV mirror radiation damage resistance under long-term free-electron laser exposures below the single-shot damage threshold

Understanding laser beam brightness: A review and new prospective in material processing

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