XUV Imaging

Short wavelength radiation in the extreme ultraviolet (XUV) and soft X-ray spectral region enables high contrast and high-resolution imaging. In our group, we utilize the highly coherent radiation of table-top high harmonic sources to perform lensless imaging with wavelength-scale resolution down to only a few nanometers. This novel method offers insights into e.g biological samples, which is so far not possible with other techniques. The employed lensless imaging methods are based on computational image formation by "digital optics". Hence, the image forming lens is replaced by an iterative algorithm or neural network, which completely eliminates aberrations and losses. This approach enables high resolution, high contrast images with a minimized dose on the sample.
In our latest experiments we used a high photon flux, 18 nm wavelength, laser-like high-order harmonic source to achieve record imaging performance by different lensless methods. A record resolution of 13 nm has been achieved using coherent diffractive imaging on isolated samples [1]. Waveguiding effects in nanoscale structures have been observed with wavelength-scale resolution via Fourier-transform holography [2]. Recently, we achieved 45 nm resolution on an extended Siemens-Star test object by employing Ptchography, a scanning lensless imaging technique [3], which enables real-world applications e.g. in EUV metrology and biology.

Our current research is focused on pushing resolution limits to the few-nm range [4], exploring broadband (potentially material-selective and ultrafast) lensless imaging, and enabling imaging in the so-called waterExternal link window for biological applicationsExternal link.