Frustrated Total Internal Reflection Fiber-Optic Small-Motion Sensor for Hydrophone Use.
DEPARTMENT OF THE NAVY WASHINGTON DC
Pagination or Media Count:
A method and apparatus for sensing motion relies upon the total light transmitted by an optical fiber is disclosed. The fiber is wound in a spiral coil and cemented to a rigid base and a portion of the fibers cladding is removed exposing its core. A highly refractive plate is placed closely adjacent the exposed core. When the plate is displaced, in intercepts at least a portion of the evanescent field that is adjacent to the spiral core. The intercepted portion reduces the total amount of light otherwise projected through the coiled optic fiber so that a detector can provide representations of the amplitude and frequency of the plate motion. The plate only penetrates the fibers evanescent optical field which is associated with the total internal reflection at the glass-to-air interface at the fibers surface. Adjusting devices and pressure compensation optionally are employed making this device suitable for use has a hydrophone.
- Acoustic Detection and Detectors
- Optical Detection and Detectors
- Fiber Optics and Integrated Optics