Abstract
Structural integrity can be examined using methods that evaluate response to vibration, such as hammering tests and ultrasonic inspections. Fiber optic sensors are expected to allow structural health monitoring in harsh environments where conventional electric sensors cannot be used. Recently, detection of vibration with a fiber Bragg grating (FBG) has been intensively investigated, because FBGs have many advantages such as multifunction abilities, multiplexing, and electromagnetic immunity. In using previously proposed systems incorporating FBGs, however, there was a technical difficulty in detecting ultrasound under varying temperatures and strain conditions. We developed a novel system that overcomes this technical barrier. Our system is also capable of detecting vibrations across a broad frequency band from several Hz to around 2 MHz. This paper presents how our compact and economical vibration-detection system with an FBG sensor was developed.
