Abstract: A fiber optic interferometric sensor system utilizing a reference transducer and an optical source having a short coherence length in comparison to the optical transit time through the sensor. The optical source is used to interrogate a remotely located fiber optics sensor which has an optical path difference between two reflecting surfaces or between one reflecting surface and a beam transmitted through the sensor such that the optical beams are incoherent for the optical source used. The reflected and transmitted beams are then coupled to a reference transducer, located remotely from the sensor and preferably near the electronic processing circuitry. The reference transducer is designed with an optical path length difference to produce a coherent combination for the optical path length differences of both the sensor and the reference transducer thereby forming a highly sensitive interferometer.

Abstract: A fiber optic interferometric sensor system utilizing a reference transducer and an optical source having a very short coherence length, typically about 80 microns. The optical source is used to activate a remotely located fiber optic sensor which has an optical path defference between two reflecting surfaces such that the reflected optical beams are incoherent for the optical source used. The reflected beams are then coupled to a reference transducer, located remotely from the sensor and preferably near the electronic processing circuitry. The reference transducer is designed with an optical path length difference to produce a coherent combination for the optical path length differences of both the sensor and the reference transducer thereby forming a highly sensitive interferometer.

Abstract: An electronic receiver circuit for receiving and amplifying optical signals is disclosed. The optical signal is applied to a photodiode which generates a current signal that passes through a source load with a high resistance or impedance relative to the impedances associated with the desired bandwidth of the optical signal. The current signal is amplified and buffered by an amplifier circuit which can drive low output impedances while maintaining the proper voltage level on the high impedance source load. The receiver circuit also maintains a wide signal bandwidth from RF to microwave frequencies, holds pre-amplifier distortion to very low levels and still yields a high signal-to-noise ratio.