All light type multi-point vibration measurement system using an always vibrating FBG built-in sensor can be operated under the severe environment

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K06167
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Dynamics/Control
• Research Institution: Gifu National College of Technology
• Principal Investigator: Kumazaki Hironori 岐阜工業高等専門学校, その他部局等, 教授 (70270262)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: FBG / グレーティングファイバ / 振動測定 / 微細加工

Outline of Final Research Achievements

Fiber Bragg gratings (FBGs) micromachined by anisotropic reactive ion etching (RIE) using CF4 plasma was previously evaluated as a vibration sensor probe. However, it was not realistic to use it solely for vibration measurement because the etched FBG sensor was fragile mechanically. Then, the FBG attached to on a board spring was experimented and evaluated for vibration measurement. Specifically, a 5-mm-long FBG with a reflection center wavelength of 1550 nm was adhered on a 20-mm-long and 2-mm-width board spring with thickness of 0.2 mm made of SUS-304. The voltage equivalent to amplitude monotonically increased with the mechanical vibration amplitude (~200 μm, 50 Hz) for sensor FBG B-10 (cantilever type, 10 mm length). Although a problem remained in the responsiveness, it can be used for vibration measurement with amplitude accuracy of about 20 μm.

Free Research Field

光ファイバセンサ

Academic Significance and Societal Importance of the Research Achievements

振動を光学的に遠隔測定できるシステムを提案し、FBGを加工したセンサについて検討を行った。FBGの断面に非対称性をもたせることでコアに歪みを生じるため、反射波長が変化することになる。これまで取り組んできた光ファイバの微細加工および測定技術、FBGを組み合わせれば、数十km程度の遠隔地でも周囲環境の影響を受けることなく、低周波微振動の安定的な検出が可能な光学センサに応用可能となる。光ファイバ内蔵の振動子により、小型で、耐環境性および遠隔監視性に優れた振動センサが実現できるだけでなく、光学的なシステムにより地震の予知や検知等ができれば現場で電気を必要とせず、防災リスクの低減を図ることができる。