中文摘要：

本文提出并展示了两种光纤超声传感系统,一种是基于菲索干涉仪的结构,另一种是类萨格奈克干涉仪的结构.当系统中光纤传感器采用长跨度光纤时,可实现结构整体内部是否有微裂纹所导致超声发射的情况监测.系统中的光纤传感器部分也可以选用一段短光纤或绕成一个光纤环,从而实现单点的局部探测.文中分析了作为传感的光纤与超声的相互作用.实验上,将1 m长的光纤作为一段直线传感器和绕成光纤环形点传感器分别埋入混凝土试件中,进行了10、25和50 kH超声测量实验.结果表明,这两种光纤传感器均具无损检测的应用潜力.尤其是长尺度光纤传感器更适合于监测大尺度混凝土建筑结构的由于内部微裂纹的发生及其发展情况,对于评估结构的健康状况具有十分重要的意义.

英文摘要：

Based on a fiber optic Fizeau and Sagnac - like interferometric sensing techniques, the ultrasonic fiber optic sensing systems have been developed and demonstrated. In the sensing system, a long - gauge - length fiber as detector has been used for indication of the existence of acoustic emission. The interaction between fiber sensor and the ultrasonic wave are analyzed. The experiments were conduc- ted by 1 - meter gauge length fiber optic sensor which embedded in the concrete specimens in straight and coiled manner. The test results of ultrasonic wave at frequency 10, 25 and 50 kHz are given. It shows that the fiber optic Fizeau and Sagnac -like interferometric sensors have potential for NDT applications. Especially its long - gauge - length fiber is well suitable for evaluating large - scale concrete structure and monitoring the existence of acoustic emission company with occurring of micro - crack and its developing inside the concrete structures.