Water Window Ptychographic Imaging with Characterized Coherent X-rays

TL;DR

This study demonstrates high-resolution ptychographic imaging in the water window using coherent soft X-rays at 500 eV, achieving sub-100 nanometer resolution of biological samples.

Contribution

It introduces a method for water window ptychography with characterized coherence and reports the first high-resolution imaging of biological specimens at this energy range.

Findings

Achieved 53 nm resolution on test samples.

Imaged fossil diatom at better than 90 nm resolution.

Validated the use of a non-redundant array for coherence measurement.

Abstract

We report on a ptychographical coherent diffractive imaging experiment in the water window with focused soft X-rays at $500~\mathrm{eV}$. An X-ray beam with high degree of coherence was selected for ptychography at the P04 beamline of the PETRA III synchrotron radiation source. We measured the beam coherence with the newly developed non-redundant array method. A pinhole $2.6~\mathrm{\mu m}$ in size selected the coherent part of the beam and was used for ptychographic measurements of a lithographically manufactured test sample and fossil diatom. The achieved resolution was $53~\mathrm{nm}$ for the test sample and only limited by the size of the detector. The diatom was imaged at a resolution better than $90~\mathrm{nm}$.