The interference effects in the centers of "disklike" whole cylinders of different photoelastic materials loaded by uniaxial forces acting along diameters are studied. The intensity of the light passing through the cylinder is analyzed and a few numerical models of the phenomenon are constructed and compared with the experimental results. The dispersive character of the "photoelastic constant" is shown and its consequence for the effect are emphasized. A computer-aided spectrometer was specially constructed for the research and is the heart of a semiautomatic measurement stand. The utilization of the effect to construct an optical force sensor is shown.