Patent ID: 6870975

Claim:
A fiber optic sensor for detecting a change in displacement due to mechanical, thermal or other conditions, the fiber optic sensor comprising: a lead fiber having a first end with a connector for connecting the lead fiber to an interferometric demodulation instrument and a second end having a first ferrule with a partially reflective surface having a reflectivity of approximately 3%; a sensor fiber having a first end with a partially reflective surface and a second end having a second ferrule with a partially reflective surface having a reflectivity of approximately 24%, the sensor fiber having an optical path length which varies in accordance with the change in displacement; and a sleeve for connecting the second end of the lead fiber to the second end of the sensor fiber so as to leave a gap between the partially reflective surfaces of the first and second ferrules, the gap being adjusted between 25-200 microns to provide an optimal light signal to the instrument such that the light returned to the instrument by all reflecting elements is of equal intensity to maximize an interferometric signal.