Patent ID: 9304017
Filing Date: 2016-04-05
CPC Classification: G01D,G01H,G01L,G01M

Claim Text:
1. A distributed optical fibre sensor for determining at least one physical parameter as a function of position along a sensing fibre from properties of probe light backscattered within the sensing fibre, the sensor comprising: a probe light source arranged to launch probe light pulses into the sensing fibre, the probe light pulses including successive groups each of two or more probe light pulses having different optical wavelengths to each other; a detector arranged to detect probe light backscattered in said sensing fibre, including separately detecting light of each of said different wavelengths; and an analyser arranged to determine said parameter as a function of position along the sensing fibre from said detected backscattered probe light of one or more of said wavelengths, wherein the analyser is arranged to combine data derived from the detected backscatter of said two or more probe light pulses vectorially, and to determine said physical parameter from said vectorially combined data, and wherein the sensor is arranged to adjust one or more of said plurality of different wavelengths to control the relative phase bias or biases between interferometric signals in the backscattered probe light arising from respective probe light pulses of said different wavelengths, such that the relative phase bias or biases exhibit approximately constant phase spacing along the length of the sensing fibre.