Fiber optics strain gauge

Abstract

We have demonstrated a fiber optics strain gauge measur- ing strains of <0.4 X 10-6. It utilizes the change in optical pathlength caused by strain in a fiber. Strain is measured as motion of fringes in an optical interference pattern. Optical phase shifts per unit strain per unit fiber length of about 1.2 X 107 m-1 are predicted by theory and observed in experiments.