Fiber Optic System for Measuring Electric Fields.
DEPARTMENT OF THE NAVY WASHINGTON DC
Pagination or Media Count:
A fiber optic sensor system and associated technique is disclosed for measuring an electric field wherein a sensor arm of optical fiber cable is wound about a core member of piezoelectric material. A reference arm of optical fiber cable substantially equal in optical path length to the sensor arm is isolated and connected in parallel to the sensor arm so that coherent light generated by a single mode laser source may be split through the fiber-optic arms and recombined after passage therethrough for phase comparison. When subjected to a local electric field, the core member of piexoelectric material varies in dimensions and thereby causes a change in the strain in the optical fiber cable of the sensor arm. Relative phase changes in the coherent light caused by the resulting optical path length change of the strained sensor arm are detected by a passive homodyne demodulator and determinative of the value of the local electric field. A vane-type shield is adapted to be rotated about the core member for periodically reducing the local electric field to near zero thereby providing a reference level for field measurement.
- Optical Detection and Detectors
- Fiber Optics and Integrated Optics