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<title>Fiber optic acoustic emission sensor based on a fused tapered coupler</title>

2002; SPIE; Volume: 4694; Linguagem: Inglês

10.1117/12.472633

1996-756X

Crispin Doyle, Rongshen Chen, Tongyu Liu, Gangtie Zheng, Gerard F. Fernando,

Mechanical and Optical Resonators

This paper introduces a new type of fiber-optic acoustic emission (AE) sensor, based on a fused tapered 2x2 coupler. Laser light is injected into one input fiber and variations in the splitting ratio, caused by the passage of an ultrasonic pulse through the coupling region, are measured via a differential detection scheme. The sensor was designed to be directly compatible with an existing AE instrumentation system (the MISTRAS system from Physical Acoustics). Sensors were mounted on the surface of and embedded within glass-reinforced polyester laminates. They were excited with simulated AE signals and their performance was compared to that of a conventional piezoelectric AE transducer. The characteristics of the response of the fiber-optic sensor were similar to those of a commercial piezoelectric transducer. A signal-to noise ratio of 45 dB was achieved.