Multiple Axis, Fiber Optic Interferometric Seismic Sensor

Abstract

A mechanical vibration transducer includes a seismic mass is supported by a plurality of cylindrical silicone rubber mandrels. Each mandrel is wound with a length of optical fiber which has a reflective end and a transmissive end. A case surrounds the assemblage and is connected to the supports. When the case is displaced, the supports change diameter in response to the relative motion between the seismic mass and the case. This change in diameter is translated to a change in length of the optical fiber. By using the fibers as arms of a michelson interferometer, a sensitive instrument responsive to displacing vibrations is obtained. This instrument is energized entirely by light transmitted through optical fiber waveguides and whose information is transmitted to the observor using only light. waves in optical fibers.