Staircase array of inclined refractive multi-lenses for large field of view pixel super-resolution scanning transmission hard X-ray microscopy

Talgat Mamyrbayev, Katsumasa Ikematsu, Hidekazu Takano, Yanlin Wu, Kenji Kimura, Patrick Doll, Arndt Last, Atsushi Momose, Pascal Meyer

Research output: Contribution to journalArticlepeer-review

Abstract

Owing to the development of X-ray focusing optics during the past decades, synchrotron-based X-ray microscopy techniques allow the study of specimens with unprecedented spatial resolution, down to 10 nm, using soft and medium X-ray photon energies, though at the expense of the field of view (FOV). One of the approaches to increase the FOV to square millimetres is raster-scanning of the specimen using a single nanoprobe; however, this results in a long data acquisition time. This work employs an array of inclined biconcave parabolic refractive multi-lenses (RMLs), fabricated by deep X-ray lithography and electroplating to generate a large number of long X-ray foci. Since the FOV is limited by the pattern height if a single RML is used by impinging X-rays parallel to the substrate, many RMLs at regular intervals in the orthogonal direction were fabricated by tilted exposure. By inclining the substrate correspondingly to the tilted exposure, 378000 X-ray line foci were generated with a length in the centimetre range and constant intervals in the sub-micrometre range. The capability of this new X-ray focusing device was first confirmed using ray-tracing simulations and then using synchrotron radiation at BL20B2 of SPring-8, Japan. Taking account of the fact that the refractive lens is effective for focusing high-energy X-rays, the experiment was performed with 35 keV X-rays. Next, by scanning a specimen through the line foci, this device was used to perform large FOV pixel super-resolution scanning transmission hard X-ray microscopy (PSR-STHXM) with a 780 ± 40 nm spatial resolution within an FOV of 1.64 cm × 1.64 cm (limited by the detector area) and a total scanning time of 4 min. Biomedical implant abutments fabricated via selective laser melting using Ti-6Al-4V medical alloy were measured by PSR-STHXM, suggesting its unique potential for studying extended and thick specimens. Although the super-resolution function was realized in one dimension in this study, it can be expanded to two dimensions by aligning a pair of presented devices orthogonally.

Original languageEnglish
Pages (from-to)732-740
Number of pages9
JournalJournal of Synchrotron Radiation
Volume28
DOIs
Publication statusPublished - 2021 May 1
Externally publishedYes

Keywords

  • deep X-ray lithography and electroplating
  • inclined refractive X-ray multi-lens array
  • pixel super-resolution
  • scanning transmission hard X-ray microscopy

ASJC Scopus subject areas

  • Radiation
  • Nuclear and High Energy Physics
  • Instrumentation

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