High-resolution and high-throughput Raman spectroscopic imaging using structured illumination and compressive sensing

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K04188
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Meijo University
• Principal Investigator: Kimachi Hirohisa 名城大学, 理工学部, 教授 (30324453)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 構造化照明 / 圧縮センシング / ラマン分光法 / ２次元イメージング / ひずみ分布

Outline of Final Research Achievements

In this study, we aimed to develop a two-dimensional Raman spectroscopic imaging microscope that combines structured illumination method and compressive sensing technique for high-spatial resolution and fast two-dimensional mapping of material phases, stresses and strains in the observed region. First, the optical system for structured illumination using a laser (wavelength 488nm) was constructed and the obtained images were compared with results from optical simulations. Then, the possibility of two-dimensional Raman spectroscopic imaging using structured illumination method was examined. Next, the Raman spectrum was reconstructed from the weak Raman spectrum with low signal-to-noise ratio by compressed sensing technique. we developed the technique to reconstruct the two-dimensional Raman image from the signal obtained by one-time two-dimensional structured illumination. This technique was applied to reconstruction of the three-dimensional strain image.

Free Research Field

材料力学

Academic Significance and Societal Importance of the Research Achievements

近年，SiCやGaNなどのパワーデバイスの性能や寿命が，製造過程や実働環境下で発生するひずみや材料中の欠陥に影響を受けるため，デバイススケールから問題領域を抽出し，ひずみや欠陥を定量的に評価することが重要となっている．本研究では，評価技術として顕微ラマン分光法が有力な候補となる可能性があることを示した．また，2次元構造化照明では９回の測定で高分解能な画像にするが，圧縮センシングを用いることで１回の測定で，ラマンやひずみの２次元イメージングを再構築ができることを示した点は高速化の点で意義がある．また，深さ方向への間引き走査で、３次元イメージングが可能であることを示した点も意義があると思われる．