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Title: Efficient focusing of hard x rays to 25 nm by a total reflection mirror

Abstract

Nanofocused x rays are indispensable because they can provide high spatial resolution and high sensitivity for x-ray nanoscopy/spectroscopy. A focusing system using total reflection mirrors is one of the most promising methods for producing nanofocused x rays due to its high efficiency and energy-tunable focusing. The authors have developed a fabrication system for hard x-ray mirrors by developing elastic emission machining, microstitching interferometry, and relative angle determinable stitching interferometry. By using an ultraprecisely figured mirror, they realized hard x-ray line focusing with a beam width of 25 nm at 15 keV. The focusing test was performed at the 1-km-long beamline of SPring-8.

Authors:
; ; ; ; ; ; ; ; ; ;  [1];  [2];  [3];  [2];  [2]
  1. Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)
  2. (Japan)
  3. (JASRI), 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)
Publication Date:
OSTI Identifier:
20971800
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 90; Journal Issue: 5; Other Information: DOI: 10.1063/1.2436469; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; BEAM PROFILES; EFFICIENCY; FABRICATION; FOCUSING; HARD X RADIATION; INTERFEROMETRY; KEV RANGE 10-100; MIRRORS; NANOSTRUCTURES; REFLECTION; SPATIAL RESOLUTION; SPECTROSCOPY; SPRING-8 STORAGE RING

Citation Formats

Mimura, Hidekazu, Yumoto, Hirokatsu, Matsuyama, Satoshi, Sano, Yasuhisa, Yamamura, Kazuya, Mori, Yuzo, Yabashi, Makina, Nishino, Yoshinori, Tamasaku, Kenji, Ishikawa, Tetsuya, Yamauchi, Kazuto, Center for Ultra Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, SPring-8/Japan Synchrotron Radiation Research Institute, SPring-8/RIKEN, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, and Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871. Efficient focusing of hard x rays to 25 nm by a total reflection mirror. United States: N. p., 2007. Web. doi:10.1063/1.2436469.
Mimura, Hidekazu, Yumoto, Hirokatsu, Matsuyama, Satoshi, Sano, Yasuhisa, Yamamura, Kazuya, Mori, Yuzo, Yabashi, Makina, Nishino, Yoshinori, Tamasaku, Kenji, Ishikawa, Tetsuya, Yamauchi, Kazuto, Center for Ultra Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, SPring-8/Japan Synchrotron Radiation Research Institute, SPring-8/RIKEN, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, & Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871. Efficient focusing of hard x rays to 25 nm by a total reflection mirror. United States. doi:10.1063/1.2436469.
Mimura, Hidekazu, Yumoto, Hirokatsu, Matsuyama, Satoshi, Sano, Yasuhisa, Yamamura, Kazuya, Mori, Yuzo, Yabashi, Makina, Nishino, Yoshinori, Tamasaku, Kenji, Ishikawa, Tetsuya, Yamauchi, Kazuto, Center for Ultra Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, SPring-8/Japan Synchrotron Radiation Research Institute, SPring-8/RIKEN, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, and Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871. Mon . "Efficient focusing of hard x rays to 25 nm by a total reflection mirror". United States. doi:10.1063/1.2436469.
@article{osti_20971800,
title = {Efficient focusing of hard x rays to 25 nm by a total reflection mirror},
author = {Mimura, Hidekazu and Yumoto, Hirokatsu and Matsuyama, Satoshi and Sano, Yasuhisa and Yamamura, Kazuya and Mori, Yuzo and Yabashi, Makina and Nishino, Yoshinori and Tamasaku, Kenji and Ishikawa, Tetsuya and Yamauchi, Kazuto and Center for Ultra Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 and SPring-8/Japan Synchrotron Radiation Research Institute and SPring-8/RIKEN, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 and Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871},
abstractNote = {Nanofocused x rays are indispensable because they can provide high spatial resolution and high sensitivity for x-ray nanoscopy/spectroscopy. A focusing system using total reflection mirrors is one of the most promising methods for producing nanofocused x rays due to its high efficiency and energy-tunable focusing. The authors have developed a fabrication system for hard x-ray mirrors by developing elastic emission machining, microstitching interferometry, and relative angle determinable stitching interferometry. By using an ultraprecisely figured mirror, they realized hard x-ray line focusing with a beam width of 25 nm at 15 keV. The focusing test was performed at the 1-km-long beamline of SPring-8.},
doi = {10.1063/1.2436469},
journal = {Applied Physics Letters},
number = 5,
volume = 90,
place = {United States},
year = {Mon Jan 29 00:00:00 EST 2007},
month = {Mon Jan 29 00:00:00 EST 2007}
}
  • Takano et al. report the focusing of 10-keV X-rays to a size of 14.4 nm using a total-reflection zone plate (TRZP). This focal size is at the diffraction limit for the optic's aperture. This would be a noteworthy result, since the TRZP was fabricated using conventional lithography techniques. Alternative nanofocusing optics require more demanding fabrication methods. However, as I will discuss in this Comment, the intensity distribution presented by Takano et al. (Fig. 4 of ref. 1) is more consistent with the random speckle pattern produced by the scattering of a coherent incident beam by a distorted optic than withmore » a diffraction-limited focus. When interpreted in this manner, the true focal spot size is {approx}70 nm: 5 times the diffraction limit. When a coherent photon beam illuminates an optic containing randomly distributed regions which introduce different phase shifts, the scattered diffraction pattern consists of a speckle pattern. Each speckle will be diffraction-limited: the peak width of a single speckle depends entirely on the source coherence and gives no information about the optic. The envelope of the speckle distribution corresponds to the focal spot which would be observed using incoherent illumination. The width of this envelope is due to the finite size of the coherently-diffracting domains produced by slope and position errors in the optic. The focal intensity distribution in Fig. 4 of ref. 1 indeed contains a diffraction-limited peak, but this peak contains only a fraction of the power in the focused, and forms part of a distribution of sharp peaks with an envelope {approx}70 nm in width, just as expected for a speckle pattern. At the 4mm focal distance, the 70 nm width corresponds to a slope error of 18 {micro}rad. To reach the 14 nm diffraction limit, the slope error must be reduced to 3 {micro}rad. Takano et al. have identified a likely source of this error: warping due to stress as a result of zone deposition. It will be interesting to see whether the use of a more rigid substrate gives improved results.« less
  • In response to the conjecture that the numerical aperture of x-ray optics is fundamentally limited by the critical angle of total reflection, the concept of adiabatically focusing refractive lenses was proposed to overcome this limit. Here, we present an experimental realization of these optics made of silicon and demonstrate that they indeed focus 20 keV x rays to a 18.4 nm focus with a numerical aperture of 1.73(9) × 10 –3 that clearly exceeds the critical angle of total reflection of 1.55 mrad.
  • In this study, we designed, fabricated, and evaluated a hard x-ray focusing mirror having an ideally focused beam with a full width at half maximum in the intensity profile of 36 nm at an x-ray energy of 15 keV. The designed elliptically curved shape was fabricated by a computer-controlled fabrication system using plasma chemical vaporization machining and elastic emission machining, on the basis of surface profiles accurately measured by combining microstitching interferometry with relative angle determinable stitching interferometry. A platinum-coated surface was employed for hard x-ray focusing with a large numerical aperture. Line-focusing tests on the fabricated elliptical mirror aremore » carried out at the 1-km-long beamline of SPring-8. A full width at half maximum of 40 nm was achieved in the focused beam intensity profile under the best focus conditions.« less
  • An x-ray beam with energy of 20.5 keV has been efficiently focused down to a spot size as small as 90 nmx90 nm by a Kirkpatrick-Baez reflecting mirrors device. The first mirror, coated with a graded multilayer, plays both the role of vertical focusing device and monochromator, resulting in a very high flux (2x10{sup 11} photons/s) and medium monochromaticity ({delta}E/E{approx}10{sup -2}). Evaluation of the error contributions shows that the vertical focus is presently limited by the mirror figure errors, while the horizontal focus is limited by the horizontal extension of the x-ray source. With a gain in excess of amore » few million, this device opens up new possibilities in trace element nanoanalysis and fast projection microscopy.« less
  • The spatial resolution of scanning x-ray microscopy depends on the beam size of focused x rays. Recently, nearly diffraction-limited line focusing has been achieved using elliptical mirror optics at the 100 nm level. To realize such focusing two-dimensionally in a Kirkpatrick-Baez system, the required accuracies of the mirror aligners in this system were estimated using optical simulators based on geometrical or wave-optical theories. A focusing unit fulfilling the required adjustment accuracies was constructed. The relationships between alignment errors and focused beam profiles were quantitatively examined at the 1 km long beamline (BL29XUL) of SPring-8 to be in good agreement withmore » the simulation results.« less