Mimura Hidekazu, Takei Yoshinori, Kume Takehiro, Takeo Yoko, Motoyama Hiroto, Egawa Satoru, Matsuzawa Yusuke, Yamaguchi Gota, Senba Yasunori, Kishimoto Hikaru, Ohashi Haruhiko
Department of Precision Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Koto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan.
Rev Sci Instrum. 2018 Sep;89(9):093104. doi: 10.1063/1.5035323.
In X-ray focusing, grazing incidence mirrors offer advantages of no chromatic aberration and high focusing efficiency. Although nanofocusing mirrors have been developed for the hard X-ray region, there is no mirror with nanofocusing performance in the soft X-ray region. Designing a system with the ability to focus to a beam size smaller than 100 nm at an X-ray energy of less than 1 keV requires a numerical aperture larger than 0.01. This leads to difficulties in the fabrication of a soft X-ray focusing mirror with high accuracy. Ellipsoidal mirrors enable soft X-ray focusing with a high numerical aperture. In this study, we report a production process for ellipsoidal mirrors involving mandrel fabrication and replication processes. The fabricated ellipsoidal mirror was assessed under partial illumination conditions at the soft X-ray beamline (BL25SU) of SPring-8. A focal spot size of less than 250 nm was confirmed at 300 eV. The focusing tests indicated that the proposed fabrication process is promising for X-ray mirrors that have the form of a solid of revolution, including Wolter mirrors.
在X射线聚焦方面，掠入射镜具有无色差和高聚焦效率的优点。尽管已经开发出用于硬X射线区域的纳米聚焦镜，但在软X射线区域尚无具有纳米聚焦性能的镜子。要设计一个在X射线能量低于1keV时能够将光束聚焦到小于100nm尺寸的系统，需要数值孔径大于0.01。这导致高精度制造软X射线聚焦镜存在困难。椭球面镜能够实现具有高数值孔径的软X射线聚焦。在本研究中，我们报告了一种椭球面镜的生产工艺，该工艺涉及心轴制造和复制过程。在SPring-8的软X射线光束线（BL25SU）的部分照明条件下对制造的椭球面镜进行了评估。在300eV时确认焦斑尺寸小于250nm。聚焦测试表明，所提出的制造工艺对于具有旋转体形式的X射线镜（包括沃尔特镜）很有前景。
