Discrimination of Temperature, Strain, and Transverse Load by Using Fiber Bragg Gratings in a Twisted Configuration

A sensing head based on two fiber Bragg gratings arranged in a twisted configuration is proposed to measure three parameters simultaneously, namely: 1) temperature, 2) strain, and 3) transverse load. One of the gratings is impressed into a high-birefringence fiber that provides two distinct spectral signatures, which, together with the signature of the second grating and the geometric characteristics of the sensing head, enable the degrees of freedom required to achieve the simultaneous measurement functionality. The resolutions achieved with this configuration for the measurement of temperature, strain, and transverse load are plusmn3.1degC, plusmn46 muepsiv, and plusmn0.01 N/mm, respectively