Development of free-form mirror for X-ray focusing with arbitrary astigmatism

2022 Fiscal Year Final Research Report

• Project/Area Number: 21K20394
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0301:Mechanics of materials, production engineering, design engineering, fluid engineering, thermal engineering, mechanical dynamics, robotics, aerospace engineering, marine and maritime engineering, and related fields
• Research Institution: The University of Tokyo
• Principal Investigator: Takeo Yoko 東京大学, 物性研究所, 助教 (50910155)
• Project Period (FY): 2021-08-30 – 2023-03-31
• Keywords: 精密計測 / 精密加工 / X線ミラー / 光学設計 / 軟X線集光

Outline of Final Research Achievements

Grazing incidence mirrors are an essential fundamental technology for focusing and shaping X-rays with high intensity and short wavelength. Most mirrors currently in practical use in the X-ray field are designed based on conic curves, which limits the degree of freedom in designing optical system.
In this study, we addressed the following three points to develop a new grazing incidence mirror with different focusing characteristics in the vertical and horizontal directions: a three-dimensional free-form design method, figure measurement, and in-situ evaluation in an optical system. As a demonstration, we fabricated a mirror with a 10x different reduction ratio between longitudinal and sagittal focusing, and confirmed the functions as designed at the soft X-ray beamline of SPring-8. This research would be deployed in various applications including soft X-ray synchrotron radiation facilities.

Free Research Field

X線光学

Academic Significance and Societal Importance of the Research Achievements

光学系を設計する際に、円形ビームが点光源から発するという仮定を用いることは多いが、実際の光源特性には必ずしも当てはまらない。物性研究や製薬の領域で欠かせない役割を果たす放射光軟X線光源はその一例である。このような光源の持つ鉛直・水平方向の非対称性を考慮に入れたうえで、それらを解消あるいは付加する光学技術が必要とされている。
本研究で開発した技術によって、これまで斜入射ミラーが2枚必要だった上述の光学系を、1枚で実現することができるようになった。これにより、多様な軟X線解析手法に最適化した照明ビームを低コストで生成可能となり、新たな物質の発見や現象の解明につながると期待される。