Patent ID: 8614795

Claim:
An apparatus for estimating a parameter, the apparatus comprising: an optical fiber including at least one core configured to be optically coupled to a light source and transmit an interrogation signal, the at least one core including a plurality of sensing locations distributed along a measurement length of the optical fiber and configured to reflect light; a reference optical path configured to transmit a reference signal, the reference optical path disposed in a fixed relationship to the at least one core and extending at least substantially parallel to the at least one core, the reference optical path including a reference reflector that defines a cavity length corresponding to the measurement length; a detector configured to receive a reflected return signal including light reflected from one or more of the plurality of sensing locations; a reference interferometer configured to receive at least a reference signal returned from the reference optical path and generate an interferometric reference signal; and a processor configured to apply the interferometric reference signal to the reflected return signal to compensate for one or more environmental parameters.