Photoelastic computer tomography: a novel measurement method for axial residual stress profile in optical fibers

A method for measuring the axial residual stress profile in optical fibers is presented. The axial stress profile on the fiber cross section is obtained from optical retardations of rays that travel laterally through the fiber. The retardations are measured for a number of fiber orientations by rotating the fiber through 180°. The stress profile is reconstructed by performing a numerical inversion of the data. This paper describes the principle, experimental setup, and measured stress profiles, as well as measurement errors and spatial resolution. It is shown that the nonaxisymmetrical stress profile can be nondestructively measured with high accuracy by using the method.