Fredrik Uhlen

MSc in Engineering Physics.
Doctoral Studies in Experimental X-Ray Physics: Diffractive X-Ray Optics.

Specialties: Physics, Nanotechnology, X-Rays, Optics, Biomedical Physics, Material science

• New diamond nanofabrication process for hard x-ray zone plates

  • J. Vac. Sci. Technol. B
  • November 2011
  Authors: Fredrik Uhlen

  The authors report on a new tungsten-hardmask-based diamond dry-etch process for fabricating
  diamond zone plate lenses with a high aspect ratio. The tungsten hardmask is structured by electron-beam lithography, together with Cl2/O2 and SF6/O2 reactive ion etching in a trilayer resist-chromium-tungsten stack. The underlying diamond is then etched in an O2 plasma. The authors demonstrate excellent-quality diamond gratings with half-pitch down to 80 nm and a height of 2.6 µm, as well as zone plates with a 75 µm diameter and 100 nm outermost zone width. The diffraction efficiency of the zone plates is measured to 14.5% at an 8 keV x-ray energy, and the imaging properties were investigated in a scanning microscope arrangement showing sub-100-nm resolution. The imaging and thermal properties of these lenses make them suitable for use with high-brightness x-ray free-electron laser sources.

• Damage investigation on tungsten and diamond diffractive optics at a hard x-ray free-electron laser

  • Optics Express
  • March 26, 2013
  Authors: Fredrik Uhlen

  Focusing hard x-ray free-electron laser radiation with extremely
  high fluence sets stringent demands on the x-ray optics. Any material
  placed in an intense x-ray beam is at risk of being damaged. Therefore, it is
  crucial to find the damage thresholds for focusing optics. In this paper we
  report experimental results of exposing tungsten and diamond diffractive
  optics to a prefocused 8.2 keV free-electron laser beam in order to find
  damage threshold fluence levels.

1. Materials Science
2. Physics
3. Optics
4. Nanotechnology
5. Thin Films
6. Microscopy
7. Scanning Electron Microscopy
8. XRD
9. Surface
10. Powder X-ray Diffraction

• Swedish

  (Native or bilingual proficiency)

• English

  (Full professional proficiency)

• French

  (Elementary proficiency)

Grupper och föreningar:

• 
  KTH Alumni, Royal Institute of Technology
• 
  Silicon Wafers