journal article

Journal Article

Text

Review of Scientific Instruments. 2016, 87(5), p. 051905

Stitching interferometry for ellipsoidal x-ray mirrors

American Institute of Physics

English

Text

2016-05

https://doi.org/10.1063/1.4950714

Hirokatsu Yumoto, Takahisa Koyama, Satoshi Matsuyama, Kazuto Yamauchi, and Haruhiko Ohashi, "Stitching interferometry for ellipsoidal x-ray mirrors", Review of Scientific Instruments 87, 051905 (2016) https://doi.org/10.1063/1.4950714.

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.

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in (citation of published article) and may be found at https://doi.org/10.1063/1.4950714.

86945

Stitching interferometry for ellipsoidal x-ray mirrors

American Institute of Physics

English

2016-05

Review of Scientific Instruments

87

5

051905

https://doi.org/10.1063/1.4950714

https://hdl.handle.net/11094/86945