Soft X-Ray Reflection Ptychography

The ongoing brightness and coherence upgrades to 4th generation synchrotron facilities are unlocking powerful new X-ray techniques for materials science. While coherent methods like x-ray ptychography offer exceptional, element-specific nanoscale resolution, their common implementation in a transmission geometry poses a significant barrier. This limitation is particularly acute for the study of quantum materials, two-dimensional electronic and magnetic systems, and functional devices, which are often fabricated on opaque substrates or are intrinsically bulk.

To overcome this challenge, we demonstrate reflection‑geometry soft X-ray ptychography as a primary imaging mode. We establish instrumental feasibility and spatial resolution using a lithographically defined test pattern on a multilayer substrate, demonstrating a resolution better than the smallest lithographic feature size of about 50~nm which is smaller than the only other report on this technique [1]. By removing the need for transmissive samples, our results establish reflection ptychography as a powerful, nondestructive tool for probing nanoscale phenomena. This work highlights the potential of reflection-based coherent imaging to open a new window into the properties of functional materials without restrictive and often destructive sample preparation.

[1] Popescu, H., Fortuna, F., Delaunay, R., Jaouen, N., Spezzani, C., & Sacchi, M. (2021). Soft X-ray Lensless Imaging in Reflection Mode. Photonics, 8(12), 569. https://doi.org/10.3390/photonics8120569