http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Signal processing for fiber optic acoustic sensor system
A new scheme for optic detection of sound waves based upon fiber optic interferometer is presented. Multiple fiber Fabry-Perot interferometers (FFPI) are used as arrayed sensor elements inside the cable. The sensors are interrogated with light pulses from a single mode laser. Signals from multiple sensors in the array are separated and demultiplexed. The acoustic pressure information is determined by processing the returned optical pulses using a fiber Mach-Zehnder interferometer as an optical phase compensator. Two passive demodulation techniques based on a 3 by 3 output coupler in the Mach-Zehnder interferometer provide a way to eliminate phase fading suffered inside the interferometric sensors. System measurements utilizing the two techniques were demonstrated; and the linearity and stability of system were examined. A new design to overcome polarization fading inside the fiber interferometer system based upon rotation of the input optical polarization is presented. The fiber is modeled as a birefringence cavity. Simulation based on fiber birefringence models is carried out; the optimum polarization rotation scheme has been verified, and the worst case fading has been determined.
"Major subject: Electrical Engineering".
Issued also on microfiche from Lange Micrographics.
Includes bibliographical references (leaves 53-56).