The effectiveness of surface-bonded and embedded optical fibers for the detection of ultrasonic Lamb waves in 2–3-mm-thick steel, carbon-fiber-reinforced plastic (CFRP) and glass-reinforced plastic (GRP) plates are compared. A novel integrating ultrasonic sensor was achieved using the signal arm of an actively stabilized 633-nm homodyne Mach–Zehnder fiber interferometer which was either bonded directly to the plate surface or spliced to single-mode fibers embedded within a composite plate during manufacture. An embedded fiber is shown to be about 20 times more sensitive to Lamb wave motions than a surface-bonded fiber. However, the latter may be more practical.
© 1996 Optical Society of America
S. G. Pierce, W. R. Philp, A. Gachagan, A. McNab, G. Hayward, and B. Culshaw, "Surface-bonded and embedded optical fibers as ultrasonic sensors," Appl. Opt. 35, 5191-5197 (1996)