The application of differential interferometry to bulk wave measurements can be analyzed using the kinematic formulation of the photoelastic effect. For isotropic linearly elastic materials, a standing longitudinal wave changes the indicatrix from a sphere to an ellipsoid of revolution with axes parallel and perpendicular to the direction of propagation of the acoustic wave. If the probing light is linearly polarized, differential interferometry produces a maximum signal when the polarization of the light is perpendicular to the direction of propagation. This prediction is confirmed by experiment. The case of standing transverse waves can be analyzed in a similar manner.
© 1983 Optical Society of America
Hugh M. South and C. Harvey Palmer, "Analysis of two-beam interferometry for bulk wave measurements," Appl. Opt. 22, 2854-2859 (1983)