50-nm-resolution full-field X-ray microscope without chromatic aberration using total-reflection imaging mirrors

• Published in: Scientific reports Vol. 7; no. 1; p. 46358
• Main Authors: Matsuyama, Satoshi, Yasuda, Shuhei, Yamada, Jumpei, Okada, Hiromi, Kohmura, Yoshiki, Yabashi, Makina, Ishikawa, Tetsuya, Yamauchi, Kazuto
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 13.04.2017
• Subjects: Optics; Spatial discrimination; Tungsten; Ultrastructure; X-rays
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep46358

X-ray spectromicroscopy with a full-field imaging technique is a powerful method for chemical analysis of heterogeneous complex materials with a nano-scale spatial resolution. For imaging optics, an X-ray reflective optical system has excellent capabilities with highly efficient, achromatic, and long-working-distance properties. An advanced Kirkpatrick-Baez geometry that combines four independent mirrors with elliptic and hyperbolic shapes in both horizontal and vertical directions was developed for this purpose, although the complexity of the system has a limited applicable range. Here, we present an optical system consisting of two monolithic imaging mirrors. Elliptic and hyperbolic shapes were formed on a single substrate to achieve both high resolution and sufficient stability. The mirrors were finished with a ~1-nm shape accuracy using elastic emission machining. The performance was tested at SPring-8 with a photon energy of approximately 10 keV. We could clearly resolve 50-nm features in a Siemens star without chromatic aberration and with high stability over 20 h. We applied this system to X-ray absorption fine structure spectromicroscopy and identified elements and chemical states in specimens of zinc and tungsten micron-size particles.