Patent ID: 6285806
Filing Date: 2001-09-04
Classification: G01D,G01H,G01M

Abstract:
A fiber optic sensor array for detecting a physical condition, the fiber optic sensor array comprising:bit sequence generating means for generating a pseudo-random bit sequence;light source means, receiving the pseudo-random bit sequence, for emitting a light beam which is modulated in accordance with the pseudo-random bit sequence;an optical fiber disposed to receive the light beam so that the light beam propagates in the optical fiber in a first direction, the optical fiber comprising a plurality of fiber segments disposed in series, each of the plurality of fiber segments having an optical characteristic which varies in accordance with the physical condition, the fiber segments being separated by means for weakly reflecting portions of the light beam to form return optical signals which propagate in the optical fiber in a second direction which is opposite to the first direction, each of the return optical signals representing an effect of the physical condition on the light beam;photodetecting means, receiving the return optical signals, for producing a photodetector output which represents a sum of the return optical signals;time delay means, receiving the pseudo-random bit sequence, for producing a time-delayed pseudo-random bit sequence, said time delay means comprising means for producing a plurality of time delayed pseudo-random bit sequences, each having a different time delay;correlating means, receiving the time-delayed pseudo-random bit sequence and the photodetector output, for performing a correlation between the time-delayed pseudo-random bit sequence and the photodetector output to produce a correlation result representing one of the return optical signals, said correlating means comprising means for receiving a plurality of time-delayed pseudo-random bit sequences, for producing a plurality of correlations to produce a plurality of correlation results, each representing a different one of the return optical signals; andsubtracting means, receiving the plurality of correlation results, for calculating a difference between two of the return optical signals to determine an effect on the light beam by one of the fiber segments.