Non-destructive Testing Using Fiber Bragg Gratings

Abstract

  Fiber Bragg grating (FBG) is a wavelength modulation fiber-optic sensor and the central wavelength of light reflected from FBG varies with vibration impinging on the FBG. Strain, ultrasound as well as acoustic emission (AE) can be measured from FBGs through a wavelength-light intensity conversion technique. This review presents experimental works on dynamic strain measurement and ultrasonic damage inspection using FBG sensors, and demonstrates that FBGs can function as strain and ultrasonic sensors comparable to conventional electric sensors. Furthermore, a novel FBG sensor in which optical fiber is used as ultrasonic waveguide is introduced and an experiment of continuous AE measurement using the FBG sensor is presented.