Embedded fiber optic acoustic sensor for flaw detection

Nadarajah Narendran, Mechanical Technology, Inc.
Stephen V. Letcher, Mechanical Technology, Inc.
Arun Shukla, Mechanical Technology, Inc.
Raman P. Singh, Mechanical Technology, Inc.


The applicability of an embedded fiber-optic acoustic sensor to detect internal cracks and flaws in polymeric materials has been experimentally demonstrated. The sensor is based on a remote polarimetric technique. It has been shown that proper control of the polarization and phase of the optical beam is required to obtain meaningful results. This sensor has shown promising results in determining acoustical properties of plexiglass and obtaining information regarding the location and the extent of the flaw from the amplitude of the fiber-optic sensor signal. The sensing fiber of this sensor is not modified and is mechanically intact. Therefore it is attractive for embedded fiber-optic sensing applications.