Patent ID: 7122783

Claim:
A seismic sensor system, comprising: a sensor head with a fiber Bragg gating is positioned in a detecting area, said sensor head having a head surface, a fiber optic cable and a means for damping; a light source transmits a light beam through said detecting area to an optical coupler, a portion of said light beam is directed to said fiber Bragg grating; said fiber optic cable being a part of a continuous fiber loop; fiber Bragg grating and a demodulator grating having an identical central wavelength under static conditions; a plurality of terrestrial seismic disturbances in the earth and along the ground in said detecting area generates a strain and a plurality of sound waves, said strain causing a wavelength shift in said fiber Bragg grating and a plurality of strain variations, said wavelength shift causing said fiber Bragg grating to function as an optical reflector; said portion of the light beam being reflected back from said fiber Bragg grating into said demodulator grating generates an optical signal transmitted through said continuous fiber loop to a means for photo receiving, said transmitted optical signal having an intensity related to said plurality of strain variations; a multitude of said sensor heads, each having its own fiber Bragg grating with a different frequency, are connected to said continuous fiber loop, said damping means causes said sensor head to rapidly return to a ready state after detecting a signal; said photo receiver means converts said transmitted optical signal to an analog electrical signal sent through an electronic band-pass filter and an amplifier, said analog electrical signal being collected by a means for data processing to plot said plurality of terrestrial seismic disturbances in real time, without emitting a detectable electronic signature, said multitude of sensor heads, covering said detecting area, provide a group of three-dimensional position coordinates, a plurality of velocity vectors of a moving object in said detecting area and a sensitivity of at least 1.0 μstrain; said system being tunable; and a plurality of data being collected by said data processing means with a software control program plots a plurality of collected data.