Diffractive optics for the XFEL Applied Physics Diffractive optics for the XFEL Ulrich Vogt Biomedical and X-Ray Physics Department of Applied Physics Royal Institute of Technology (KTH) Stockholm, Sweden FEL optics group: Anders Holmberg, Julia Reinspach, Daniel Nilsson, and Hans Hertz Meeting of in-kind contributors to WPG 3, Hamburg, January 2009

Motivation for diffractive optics Zone plate Resolution: Typical drN: 20-50 nm Focusing below 100 nm is relatively easy Low disturbance of wavefront quality Easy to use in practice

Fabrication of diffractive optics E-beam resist + etch mask material layer Plating mold + Plating base Substrate E-beam lithography, development, RIE RIE in material RIE in mold Electroplating Final zone plate Stripping Final zone plate

Challenges for FEL diffractive optics New materials for substrate and optic Cooling schemes for high heat load Large diameter optics (> 1 mm2) Diffraction-limited performance (low aberrations) Metrology for efficiency and wavefront testing ”Mass production” of single-shot optics  requires advanced research and development efforts

XFEL activity focus on heat load management and suited materials for SASE 1 radiation (1 Å) includes theoretical and experimental studies new nanofabrication process necessary - substrate 100 µm CVD diamond bonded to larger heat sink - zone plate out of Gold, Tantalum, Tungsten … (>1 µm thickness !) moderate diameters (<1 mm)  Similar problems as in Harald’s group (monochromator)

XFEL activity 1 µm gold zone plate on 100 µm diamond after SASE1 monochromator

Thank you for your attention!