Optical coherence tomography (OCT) is a well-established method to retrieve three-dimensional, cross-sectional images of biological samples in a non-invasive way using near-infrared radiation. The axial resolution of OCT is on the order of the coherence length lc ~ λ02/ΔλFWHM which depends on the central wavelength λ0 and the spectral width ΔλFWHM of a light source. As a consequence, the axial resolution only depends on the spectrum rather than the geometrical properties of the radiation. OCT with broadband visible and near-infrared sources typically reaches axial (depth) resolutions in the order of a few micrometers.

I will present a novel method based on OCT for cross sectional imaging with nanometer axial resolution which is referred to as XUV coherence tomography (XCT). XCT uses extreme ultra violet light (XUV), e.g., from high harmonic generation (HHG). In XCT, the coherence length of a few nanometers of broadband XUV sources is exploited. Thus, XCT extends OCT by improving the axial resolution from micrometers to nanometers. In a first step, we demonstrated XCT at synchrotron sources. Three dimensional images of nano-structured samples based on silicon and carbon were recorded. We reached an axial resolution of 12 nm in the silicon transmission window (30–99 eV) and 3 nm in the water-window (270–530 eV) – solely limited by the spectral transmission windows of the materials used. XCT can be regarded as a perfect application for laser-driven HHG sources due to their intrinsic broad bandwidths which would have disadvantages for other imaging methods such as confocal microscopy or non diffractive imaging. In addition, HHG enables XCT to become a table top nanometer imaging technique. First results of an adaption of XCT using few-cycle laser driven HHG will be presented.

Seminarraum HI-Jena, Fröbelstieg 3
Datum (Start der Veranstaltung)