XUV Coherence Tomography with Nanoscale Resolution Driven by High Harmonic Generation

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 l
_c
∝ λ
₀
²
/Δλ which depends on the central wavelength λ
₀
and the spectral width Δλ of the 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 on the order of a few micrometers [1].