BL 29 XUL
A Method of Hard X-ray Focusing with Ultraprecise Mirrors
Yoshiki Kohmura (RIKEN/SPring-8), Hidekazu Mimura (Osaka Univ.)
Oct. 16, 17. 2010

1. OVERVIEW
In this course, we will demonstrate hard X-ray focusing with a K-B mirror opticalsystem. X-ray focusing systems are installed for a high spatial resolution analysis invarious X-ray microscopic methods. In hard X-ray region, there are several focusing
instruments such as zone plates, refractive lenses and K-B mirrors. K-B mirrors areproposed in 1948 by Kirkpatrick and Baez. Two elliptically curved mirrors are used fortwo-dimensional hard X-ray focusing. This focusing system has characteristics of noachromatic aberration and high efficiency.
In the last decade, X-ray mirror fabrication technology is further improved. The degreeof an accuracy of advanced X-ray focusing mirrors is higher than 2 nm (p-v)[1-3]. At the
1 km-long beam line (BL29XUL) of SPring-8, X-ray focusing tests have been carried out.
The ideal focusing, so-called diffraction limited focusing, was realized. The focused
beam size is achieved to be 7 nm by using multilayer mirrors[4,5]. The 400 mm-longfocusing mirror with an ideal performance was also successfully fabricated. Considering
these progresses, focusing systems using ultraprecise X-ray mirrors will be widely
installed in many beamlines.
However, for two-dimensional X-ray focusing, two focusing mirrors should be aligned
precisely. Due to the high degree of freedom in mirror positions, it is difficult for manyusers to align the mirrors without a certain level of knowledge and skill. From thesereasons, there are still high barrier in installing K-B mirror system. The purpose of thiscourse is to understand a method of hard X-ray focusing with K-B mirror. In this course,
first we will present the history in the development of X-ray mirrors at SPring-8. Then,we will show the detail procedure of an alignment of two mirrors. We also explain which
axis or angles of the mirror are sensitive to the focusing state. Finally, we actuallydemonstrate the two-dimensional hard X-ray focusing. We have a plan to use a 400mm-long mirror for vertical forcing and a 200 mm-long mirror for horizontal focusing.
X-ray energy will be 15keV.

2. BEAMLINE PRACTICALS
1. Detail explanation of alignment procedure of X-ray focusing.
2. Detail explanation of experimental facility
3. Demonstration of 2 dimensional hard X-ray focusing using a K-B system in fig.1.
4. Explanation of sub-10nm hard X-ray focusing system using adaptive optical system.
(Only visit)

Vacuum chamber
200mm-long mirror
400mm-long mirror

Focal point

Figure 1 K-B focusing system with 400mm-long mirror and 200mm-long mirror(1)

K. Yamauchi, H. Mimura, K. Inagaki and Y.

Mori, "Figuring withsubnanometer-level accuracy by numerically controlled elastic emission machining",
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(2) K. Yamauchi, et al., "Microstitching interferometry for x-ray reflective optics"., Rev.
Sci. Instrum., 74, 2894-2898 (2003).
(3) H. Mimura, et al., "Relative angle determinable stitching interferometry for hard
X-ray reflective optics", Rev. Sci. Instrum., 76, 045102 (2005).
(4) H. Mimura et al, "Breaking the 10 nanometer barrier in hard X-ray focusing",
Nature Physics 6, 122 - 125 (2010).
(5) H. Mimura et el, "Efficient focusing of hard X-rays to 25nm by a total reflection
mirror", Appl. Phys. Lett. 90, 051903 (2007).