Topography using THz vortex

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04928
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 30020:Optical engineering and photon science-related
• Research Institution: The University of Tokushima
• Principal Investigator: TOKIZANE Yu 徳島大学, ポストLEDフォトニクス研究所, 講師 (80648931)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 非線形光学 / テラヘルツ波 / 干渉計測

Outline of Final Research Achievements

We conducted a basic study to realize three-dimensional measurement using a THz vortex with a spiral wavefront. We have (1) succeeded in measuring the helical vortex phase using a coaxial spiral interferometer using a near-infrared CW laser. Since the measurable axial range(MAR) is limited by the wavelength of light, (2) measurement in optical vortex phase measurement was conducted in the spiral interferometer using a two-wavelength visible light laser to generate a synthesized wavelength, which extended the possible MAR. We also constructed a system to generate THz vortex and succeeded in (3) generating a focused THz vortex (4 THz, charge 2). We also assemble the collimating optical system and conducted experiments to generate THz vortices, but no THz vortices were measured on the camera. In the future, it will be necessary to use a THz light source with higher power. As a result, we obtained a foothold for designing an optical system for THz spiral interferometer.

Free Research Field

テラヘルツ光学

Academic Significance and Societal Importance of the Research Achievements

本研究ではらせん状の波面を持つテラヘルツ(THz)渦を用いた三次元計測の実現を目的とした。基礎検討の結果、近赤外および可視領域の光で光渦干渉計を実現し、二波長光による測定範囲の拡大を実現した。またテラヘルツ波による渦発生も実現した。THz渦による三次元計測光学系の設計に必要なパラメータや基礎技術を得ることができたため、これらを応用したTHz渦計測の実現が見込まれる。これにより大型なレーザーや分割型の干渉計を必要とせずに、簡便な測定系で不透明材料の内部応力分布を可視化が期待される。