Development of highly accurate figure measurement method using high order harmonic generation source

• Project/Area Number: 17K18821
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Research Field: Mechanics of materials, Production engineering, Design engineering, and related fields
• Research Institution: The University of Tokyo
• Principal Investigator: Mimura Hidekazu 東京大学, 大学院工学系研究科(工学部), 准教授 (30362651)
• Project Period (FY): 2017-06-30 – 2020-03-31
• Project Status: Completed (Fiscal Year 2019)
• Budget Amount: ¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000); Fiscal Year 2018: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000); Fiscal Year 2017: ¥4,940,000 (Direct Cost: ¥3,800,000、Indirect Cost: ¥1,140,000)
• Keywords: 精密計測 / 位相回復法 / X線ミラー / 集光 / 形状計測 / 波面計測 / 高次高調波 / 位相回復 / 超精密計測 / Ｘ線

Outline of Final Research Achievements

In precise fabrication of products, the final accuracy is determined by the measurement method. As a method of evaluating surfaces of mirrors and lenses, various methods using light have been proposed and developed. Interferometry measures the surfaces by determining the phase information of the light. The measurement accuracy can be improved by shortening the wavelength.
In this study, we proposed the use of a high order harmonic generation (HHG) source to evaluate optical surfaces, because this light source is cost-effective and compact. In this study, we developed the phase retrieval method specialized for this source and succeeded in the wavefront measurement of a HHG beam focused by a precise mirror.

Academic Significance and Societal Importance of the Research Achievements

表面形状のナノ精度での評価は光を用いて行われている。波長の短いＸ線を用いれば測定精度の大幅な向上が期待できる。本研究では、高次高調波と呼ばれるコヒーレントな軟Ｘ線光源の利用を提案している。この光源は実験室ベースの小型の光源であり、将来的には汎用的な利用が可能になる。本研究では高次高調波を回転楕円ミラーにより集光し、その集光ビーむの波面誤差の計測に成功した。波長は10nmレベルであり、1/10程度の波面誤差精度であったとしても1nmレベルの精度を有しており、今後の超精密形状計測への利用が期待できる。

Research Products

• [Journal Article] Soft x-ray nanobeam formed by an ellipsoidal mirror (2020)
  • Author(s): Yoko Takeo, Akihiro Suzuki, Hiroto Motoyama, Yoshinori Takei, Takehiro Kume, Yusuke Matsuzawa, Yasunori Senba, Hikaru Kishimoto, Haruhiko Ohashi, and Hidekazu Mimura1Applied Physics Letters
  • Journal Title: Applied Physics Letters Volume: 116 Issue: 12 Pages: 121102-121102
  • DOI: 10.1063/1.5144932
  • Peer Reviewed
• [Presentation] 軟X線タイコグラフィを用いた回転楕円ミラーの形状評価 (2019)
  • Author(s): 竹尾陽子，鈴木明大，仙波泰徳，岸本輝，大橋治彦，三村秀和
  • Organizer: 2019年度精密工学会秋季大会学術講演会
• [Presentation] 回転楕円ミラーによる高NA集光ビームを用いた軟X線タイコグラフィ計測 (2019)
  • Author(s): 竹尾陽子、鈴木明大、仙波康徳、岸本輝、大橋治彦、三村秀和
  • Organizer: 第32回日本放射光学会年会放射光科学合同シンポジウム
• [Presentation] Fabrication of precise ellipsoidal mirrors for soft x-ray nanofocusing, (2018)
  • Author(s): Hidekazu Mimura
  • Organizer: International Workshop on X-ray Optics and Application (IWXM2018)
  • Int'l Joint Research / Invited