ABSTRACT
This chapter discusses that photoelasticity models of objects are cast or fabricated from isotropic materials and are then subjected to stress. The stress produces physical deformations that completely alter the initial isotropic character of the material. It then characterizes the material with three principal refractive indices, which are along the principal axes of the stress. A quarter-wave plate is introduced after the model, and its axes is aligned parallel to the transmission axes of the polarizer and the analyzer. In one method, we obtain only isochromatics, and hence the method is equivalent to a circular polariscope. The chapter also provides the flexibility of leisurely evaluation of the fringe pattern. In the other method, both the isochromatic and isopachic fringe patterns are obtained. The plane polariscope consists of a light source, a light filter, collimating optics to provide a collimated beam, a polarizer, an analyzer, a lens and photographic equipment.
