A method is proposed to stabilize an intrinsic fiber optic Fabry–Perot interferometric sensor embedded in a solid material for the purpose of detecting ultrasound. Without stabilization the interferometer drifts out of quadrature due to the presence of low-frequency dynamic strains. Stabilization is achieved by using active homodyne stabilization which tunes the laser frequency to maintain quadrature. A control loop shifts the laser frequency by 10 GHz at rates less than 25 Hz in order to compensate for induced drifts. The stabilization procedure was tested for a sensor embedded in an epoxy plate. Ultrasonic pulses, generated by a 5 MHz piezoelectric transducer, were detected with the embedded fiber sensor stabilized in the presence of applied low frequency strains. Improvements in sensitivity which result from stabilization are demonstrated. Additionally, a simulated acoustic emission signal, generated by a lead pencil break (Hsu-Neilson source), was detected with the sensor stabilized in the presence of dynamic strains.
|Original language||English (US)|
|Number of pages||5|
|Journal||IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control|
|State||Published - Sep 1995|
ASJC Scopus subject areas
- Acoustics and Ultrasonics
- Electrical and Electronic Engineering