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Proceedings Paper

Multiple free electron laser pulse illumination of a carbon coated silicon substrate
Author(s): Björn Siemer; Tim Hoger; Marco Rutkowski; Martina Menneken; Stefan Düsterer; Helmut Zacharias
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Paper Abstract

The fourth generation of XUV-, soft x-ray- and x-ray-light sources, like the free electron lasers FLASH and FERMI@Elettra, leads to new seminal scientific findings and technical challenges. For the facilities the question of the beam transport is of utmost importance. To provide a good reflectivity over a large range of photon energies up to about 300 eV mostly carbon coated silicon mirrors illuminated under gracing incidence angle are mostly chosen. Thereby the coating for the mirrors must tolerate high light intensities at high photon energies and also high repetition rates. In the present experiment an amorphous carbon coated silicon substrate was illuminated at photon energies of 21 nm (58 eV) and an average pulse energy of ~27 μJ. The ellipsoidal spot size of 300 μm × 600 μm at FLASH leads to a fluence of 0.019 J/cm2. The influence of multiple (100 - 20.000) light pulses to the coated surface is analyzed. Depending on the number of pulses a change in reflectivity is visible under a light microscope. Both an AFM profile and measurements with a profilometer yield no topological changes. The investigation of the illuminated spots with a microfocus Raman spectrometer shows a decrease of the carbon signal at higher pulse repetition rates.

Paper Details

Date Published: 3 May 2013
PDF: 7 pages
Proc. SPIE 8777, Damage to VUV, EUV, and X-ray Optics IV; and EUV and X-ray Optics: Synergy between Laboratory and Space III, 87770F (3 May 2013); doi: 10.1117/12.2017248
Show Author Affiliations
Björn Siemer, Westfälische Wilhelms-Univ. Münster (Germany)
Tim Hoger, Westfälische Wilhelms-Univ. Münster (Germany)
Marco Rutkowski, Westfälische Wilhelms-Univ. Münster (Germany)
Martina Menneken, Westfälische Wilhelms-Univ. Münster (Germany)
Stefan Düsterer, Deutsches Elektronen-Synchrotron (Germany)
Helmut Zacharias, Westfälische Wilhelms-Univ. Münster (Germany)

Published in SPIE Proceedings Vol. 8777:
Damage to VUV, EUV, and X-ray Optics IV; and EUV and X-ray Optics: Synergy between Laboratory and Space III
Libor Juha; René Hudec; Ladislav Pina; Saša Bajt; Richard London, Editor(s)

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