Development of ultrasound guided optical fiber sensors

近年来，光纤传感器因其抗电磁干扰、体积小、重量轻等优点而成为结构健康监测的重要传感器。传统的光纤超声传感器，如光纤光栅传感器和干涉型光纤传感器，都是基于超声微扰引起的光学特性调制，传感部分直接粘贴在被测材料上，本文主要研究光纤优越的上级超声导波特性。将光纤粘合到监测的样本。传播通过试样的超声波被结合到试样的光纤捕获，并且利用光纤布拉格光栅或压电传感器检测沿着光纤传播的超声波。首先，我们不仅从实验上而且从理论上研究了光纤对超声波传播的基本特性。第二，我们设计了一种在被测试件上安装光纤的谐振式光纤超声波传感器。然后，将光纤超声导波传感器应用于金属材料的超声无损检测。光纤超声导波传感器在金属材料的缺陷检测中表现出了足够的灵敏度，可以作为高温等恶劣环境下的候选传感器。

Recently, fiber-optic sensors have seemed promising sensors for structural health monitoring because of their electromagnetic interference immunity, small size as well as lightweight. Conventional fiber-optic ultrasonic sensors, such as fiber Bragg grating sensor and interferometric fiber optic sensors are based on the optical characteristic modulation induced by ultrasonic perturbation and the sensing part is directly bonded to the materials to be monitored.In the present study, we focused on the superior ultrasonic guide characteristics of optical fibers. Optical fiber was bonded to the monitored specimen. Ultrasound propagated through the specimen was caught by the optical fibers bonded to the specimen and ultrasound propagated along the optical fiber was detected with fiber Bragg grating or piezoelectric sensor. First, we have studied basic characteristics of optical fibers on ultrasonic propagation not only experimentally but also analytically. Second, we have developed resonant fiber-optic ultrasonic sensors by devising the installation of optical fiber to the tested specimen. Then, we have applied fiber-optic ultrasonic guide sensors to ultrasonic non-destructive testing of metallic materials. Fiber-optic ultrasonic guide sensors have been demonstrated enough sensitivity of ultrasonic detection to detect defects in metallic materials.Fiber-optic ultrasonic guide sensors can be candidate sensors which are applied to harsh environment such as elevated temperature.