Role of light ellipse in photoelasticity and new methods for isoclinic-parameter determination

In dealing with various types of polariscopes the transformations that the light ellipse undergoes as it traverses through several optical elements give a better physical insight than the conventional trigonometrical transformations that are generally applied to the light vectors. Further, an understanding of the transformations of the light ellipse suggests several interesting methods for the determination of the isoclinic parameter.