Stabilization of an embedded fiber optic Fabry-Perot sensor for ultrasound detection

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.<<ETX>>

[1]  David A. Jackson,et al.  Recent progress in monomode fibre-optic sensors , 1994 .

[2]  J. H. Cole,et al.  Broad-band ultrasonic sensor based on induced optical phase shifts in single-mode fibers , 1983 .

[3]  H F Taylor,et al.  Performance of a fiber-optic temperature sensor from -200 to 1050 degrees C. , 1988, Optics letters.

[4]  R. Measures,et al.  Fiber optic sensors focus on smart systems , 1992, IEEE Circuits and Devices Magazine.

[5]  Jan Drewes Achenbach,et al.  Stabilized Fiber Optic Sensor for Ultrasound Detection , 1995 .

[6]  A. Dandridge,et al.  Phase noise of single‐mode diode lasers in interferometer systems , 1981 .

[7]  Alex H. Kaz,et al.  Continuously tunable diode-pumped UV-blue laser source , 1993, Photonics West - Lasers and Applications in Science and Engineering.

[8]  Raymond M. Measures,et al.  Development of a fiber Fabry-Perot strain gauge , 1991, Other Conferences.

[9]  D. Hogg,et al.  Fiber optic Fabry-Perot strain gauge , 1990, IEEE Photonics Technology Letters.

[10]  Suzanne M. Ferguson,et al.  Fiber-optic interferometric sensor for the detection of acoustic emission within composite materials. , 1990, Optics letters.

[11]  H. Taylor,et al.  Embedded fiber-optic Fabry-Perot ultrasound sensor , 1990, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[12]  J. Monchalin.  Optical Detection of Ultrasound , 1986, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[13]  H. F. Taylor,et al.  Interferometric Sensors Using Internal Fiber Mirrors , 1988 .

[14]  A B Tveten,et al.  Phase compensation in interferometric fiber-optic sensors. , 1982, Optics letters.

[15]  D. Jackson.  Monomode optical fibre interferometers for precision measurement , 1985 .

[16]  H F Taylor,et al.  Metal-embedded fiber-optic Fabry-Perot sensors. , 1991, Optics letters.

[17]  H. Taylor,et al.  Optical-fiber Fabry-Perot embedded sensor. , 1989, Optics letters.

[18]  E. Udd.  Fiber Optic Smart Structures and Skins III , 1990 .