On the visibility of dislocations perpendicular to the optical axis by stress-induced birefringence in elastically and optically isotropic materials

Abstract

An analysis of stress birefringence contrast due to screw and edge dislocations is given which confirms previous experimental results obtained by the present and other authors. It differs from earlier approaches in so far as an optically active region of the dislocation is assumed. In an otherwise strew-free medium, certain dislocation types should be invisible. Long-range stresses enable all types to be observed and classified according to the symmetry of the intensity distribution.