Dynamic optical frequency domain reflectometry.

We describe a dynamic Optical Frequency Domain Reflectometry (OFDR) system which enables real time, long range, acoustic sensing at high sampling rate. The system is based on a fast scanning laser and coherent detection scheme. Distributed sensing is obtained by probing the Rayleigh backscattered light.

OFDR with double interrogation for dynamic quasi-distributed sensing.

A method for phase sensitive quasi-distributed vibration and acoustical sensing is presented. The method is based on double optical frequency domain reflectometry interrogation of a sensing fiber with an array of discrete weak reflectors. Two replicas of the interrogation signal are launched into the sensing fiber.

Correcting for spatial-resolution degradation mechanisms in OFDR via inline auxiliary points.

The spatial resolution of OFDR is normally degraded by the laser phase noise, deviations from linear frequency scan and acoustic noise in the fibers. A method for mitigating these degradation mechanisms, without using an auxiliary interferometer, via inline auxiliary points, is presented and demonstrated experimentally. Auxiliary points are points that are a priori known to have (spatial) impulse reflectivities.