Soft X-ray Lensless Imaging in Reflection Mode

Nicolas Jaouen,Renaud Delaunay,Carlo Spezzani,Franck Fortuna,Horia Popescu,Maurizio Sacchi

doi:10.3390/photonics8120569

Abstract

We report on the development and implementation of methodologies dedicated to soft X-ray imaging by coherent scattering in reflection mode. Two complementary approaches are tested, based on Fourier transform holography and on ptychography. A new method for designing holographic masks has been developed. Our results represent a feasibility test and highlight the potential and limitations of imaging in reflection mode. Reflectivity is less efficient than transmission at soft X-ray wavelengths, hampering the acquisition of good quality images. Nonetheless, it has the potential to image a wider set of samples, notably those that are not transparent to soft X-rays. Although the images obtained so far are of modest quality, these results are extremely encouraging for continuing the development of coherent soft X-ray imaging in reflection mode.

Highlights

Interest in developing instrumentation and methods for soft X-ray imaging via coherent scattering is supported by a well-documented activity of modern X-ray sources, namely synchrotron, free-electron laser (FEL) and high-harmonic generation (HHG) facilities
We have developed a setup for X-ray imaging in reflection mode based on the separate mask/sample scheme, making it possible to bring any part of the sample into the field of view
We consider that the reflection holography and ptychography experiments reported here prove the technical feasibility this method,and andptychography that the resultsexperiments achieved arereported positive

Summary

Introduction

Interest in developing instrumentation and methods for soft X-ray imaging via coherent scattering is supported by a well-documented activity of modern X-ray sources, namely synchrotron, free-electron laser (FEL) and high-harmonic generation (HHG) facilities. Techniques relying on the elastic X-ray scattering, like resonant reflectivity, diffuse scattering, diffraction and lensless microscopy, which provide a rather unique tool-set for the investigation of timely and important topics relating to the ordering and to the dynamics of spin, charge and orbital moment in complex materials. Tunable soft X-ray sources make it possible to select photon energies that match core resonances, merging the structural sensitivity of scattering with the element selectivity and sensitivity to electronic properties of a spectroscopic tool [1]. Resonant scattering in reflection mode (measuring the specular, diffuse or diffracted intensity) addresses the electronic properties, the microstructure [2,3], the magnetic structure [4,5,6,7,8,9,10], as well as the charge [11,12,13] and orbital [3,14] order with in-depth resolution [15,16]

Objectives

Methods

Results

Conclusion