Patent ID: 9557239
Date: 2017-01-31
CPC Classifications: E21B,G01B,G01D,G01L

Claim:
1. A method of determining a strain component for a selected deformation mode of a member, comprising: propagating a light through a fiber optic cable wrapped around the member, the fiber optic cable having a plurality of sensors therein; receiving light reflected at the plurality of sensors to determine a wavelength shift of the propagated light at each of the plurality of sensors, wherein each wavelength shift indicates a strain on the member at a location of a related sensor; and using a processor to: form a dataset that relates each wavelength shift for the plurality of sensors to locations of the plurality of sensors at the member, perform a transform on the dataset to obtain a spatial frequency spectrum, wherein a peak of the spatial frequency spectrum corresponds to the selected deformation mode of the member, apply an adjustable filter to the spatial frequency spectrum to select a peak of the spatial frequency spectrum that corresponds to the selected deformation mode, wherein a frequency response of the adjustable filter includes a parameter defining frequency attenuation and a cut-off frequency i where M is a total number of strain measurements, N is a total number of sensors in a single wrap of the member, and k is an index for selecting the deformation mode, and perform an inverse transform on the selected peak to determine the strain components for the selected deformation mode.