The Stress-Optical Coefficient Of Glasses And Its Dispersion As A Function Of Temperature

Optically isotropic glasses become anisotropic under mechanical stress. In this case, the refractive index depends on the orientation of the plane of vibration of an electromagnetic wave with respect to the generally 3-dimensional stress field within the glass sample. For stress analysis, however, one does not measure the refractive index as a function of the orientation of the plane of vibration, but prefers to detect and determine directly by polariscopic means the differences of the optical pathlength induced by the stress field for different planes of vibration. For this purpose, linearly or circularly polarized electromagnetic waves was used, giving rise to fringe patterns in a polariscope.