Fiber optic sensor for simultaneous measurement of strain and temperature

Abstract

We propose polarimetric and two-mode differential interferometric schemes incorporated in an elliptical-core fiber to resolve strain and temperature simultaneously. Initial results indicate accuracies of 10 jim/m and 5°C for strain and temperature measurements, respectively. A technique, based on the evaluation of the condition number of a matrix, is shown to be useful in evaluating comparative merits of multiparameter sensing schemes. Experimental results for four fibers are presented and cross-sensitivity isues are discussed.

A Review of Recent Developments in Fiber Optic Sensor Technology

“…This issue is, of course, an important consideration for many types of sensors, and a number of approaches [62][63][64] had been previously demonstrated using dual modes, two polarizations, and dual wavelength interrogation. These approaches in general produce output responses which exhibit normalized responsivity factors that are only fractionally different and thus perform poorly at separating strain and temperature perturbations.…”

Mechanical design of embedded optical fiber interferometric sensors for monitoring simple combined loads

“…In any expression involving more than one material, the material properties will be subscripted, with subscript 1 corresponding to the fiber and each higher subscript conesponding to the next outer material layer. The superscript (1) refers to the number of material layers in the structure. A member made of a single material (E,vi), either a bare fiber or a member with no embedded fiber, has…”

Temperature and strain measurement by combining ILFE and bragg grating optical fiber sensors

“…It has been demonstrated that the Bragg wavelength, Xb, is related to the grating pitch, A, and the average refractive index ne, by kb = 2neA. (3) It has been further shown that this wavelength will shift by an amount Akb as a function of the strain and temperature as…”