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Title: Stitching interferometry for ellipsoidal x-ray mirrors

Abstract

Ellipsoidal mirrors, which can efficiently produce a two-dimensional focusing beam with a single mirror, are superior x-ray focusing optics, especially when compared to elliptical-cylinder mirrors in the Kirkpatrick–Baez geometry. However, nano-focusing ellipsoidal mirrors are not commonly used for x-ray optics because achieving the accuracy required for the surface metrology of nano-focusing ellipsoidal mirrors is difficult due to their small radius of curvature along the short ellipsoidal axis. Here, we developed a surface metrology system for nano-focusing ellipsoidal mirrors using stitching interferometric techniques. The developed system simultaneously measures sub-aperture shapes with a microscopic interferometer and the tilt angles of the sub-aperture shapes with a large Fizeau interferometer. After correcting the systematic errors included in the sub-aperture shapes, the entire mirror shape is calculated by stitching the sub-aperture shapes based on the obtained relative angles between partially overlapped sub-apertures. In this study, we developed correction methods for systematic errors in sub-aperture shapes that originated from off-axis aberrations produced in the optics of the microscopic interferometer. The systematic errors on an ellipsoidal mirror were estimated by measuring a series of tilted plane substrates and the ellipsoidal substrate. From measurements of an ellipsoidal mirror with a 3.6-mm radius of curvature at the mirror center,more » we obtained a measurement repeatability of 0.51 nm (root-mean-square) in an assessment area of 0.5 mm × 99.18 mm. This value satisfies the requirements for surface metrology of nano-focusing x-ray mirrors. Thus, the developed metrology system should be applicable for fabricating nano-focusing ellipsoidal mirrors.« less

Authors:
;  [1]; ;  [2];  [1]
  1. Japan Synchrotron Radiation Research Institute/SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)
  2. Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)
Publication Date:
OSTI Identifier:
22597926
Resource Type:
Journal Article
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 87; Journal Issue: 5; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0034-6748
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ACCURACY; APERTURES; BEAMS; CHARGES; COMPARATIVE EVALUATIONS; CYLINDERS; ERRORS; FOCUSING; GEOMETRY; INTERFEROMETERS; INTERFEROMETRY; MIRRORS; OPTICS; SHAPE; SUBSTRATES; SURFACES; TWO-DIMENSIONAL CALCULATIONS; TWO-DIMENSIONAL SYSTEMS; X RADIATION

Citation Formats

Yumoto, Hirokatsu, Koyama, Takahisa, Matsuyama, Satoshi, Yamauchi, Kazuto, Ohashi, Haruhiko, and RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148. Stitching interferometry for ellipsoidal x-ray mirrors. United States: N. p., 2016. Web. doi:10.1063/1.4950714.
Yumoto, Hirokatsu, Koyama, Takahisa, Matsuyama, Satoshi, Yamauchi, Kazuto, Ohashi, Haruhiko, & RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148. Stitching interferometry for ellipsoidal x-ray mirrors. United States. https://doi.org/10.1063/1.4950714
Yumoto, Hirokatsu, Koyama, Takahisa, Matsuyama, Satoshi, Yamauchi, Kazuto, Ohashi, Haruhiko, and RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148. Sun . "Stitching interferometry for ellipsoidal x-ray mirrors". United States. https://doi.org/10.1063/1.4950714.
@article{osti_22597926,
title = {Stitching interferometry for ellipsoidal x-ray mirrors},
author = {Yumoto, Hirokatsu and Koyama, Takahisa and Matsuyama, Satoshi and Yamauchi, Kazuto and Ohashi, Haruhiko and RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148},
abstractNote = {Ellipsoidal mirrors, which can efficiently produce a two-dimensional focusing beam with a single mirror, are superior x-ray focusing optics, especially when compared to elliptical-cylinder mirrors in the Kirkpatrick–Baez geometry. However, nano-focusing ellipsoidal mirrors are not commonly used for x-ray optics because achieving the accuracy required for the surface metrology of nano-focusing ellipsoidal mirrors is difficult due to their small radius of curvature along the short ellipsoidal axis. Here, we developed a surface metrology system for nano-focusing ellipsoidal mirrors using stitching interferometric techniques. The developed system simultaneously measures sub-aperture shapes with a microscopic interferometer and the tilt angles of the sub-aperture shapes with a large Fizeau interferometer. After correcting the systematic errors included in the sub-aperture shapes, the entire mirror shape is calculated by stitching the sub-aperture shapes based on the obtained relative angles between partially overlapped sub-apertures. In this study, we developed correction methods for systematic errors in sub-aperture shapes that originated from off-axis aberrations produced in the optics of the microscopic interferometer. The systematic errors on an ellipsoidal mirror were estimated by measuring a series of tilted plane substrates and the ellipsoidal substrate. From measurements of an ellipsoidal mirror with a 3.6-mm radius of curvature at the mirror center, we obtained a measurement repeatability of 0.51 nm (root-mean-square) in an assessment area of 0.5 mm × 99.18 mm. This value satisfies the requirements for surface metrology of nano-focusing x-ray mirrors. Thus, the developed metrology system should be applicable for fabricating nano-focusing ellipsoidal mirrors.},
doi = {10.1063/1.4950714},
url = {https://www.osti.gov/biblio/22597926}, journal = {Review of Scientific Instruments},
issn = {0034-6748},
number = 5,
volume = 87,
place = {United States},
year = {2016},
month = {5}
}