Light with wavelength λ falls on a system of crossed polarizer P and analyzer A between which

Question:

Light with wavelength λ falls on a system of crossed polarizer P and analyzer A between which a Babinet compensator C is inserted (Fig. 5.33). The compensator consists of two quartz wedges with the optical axis of one of them being parallel to the edge, and of the other, perpendicular to it. The principal directions of the polarizer and the analyzer form an angle of 45 ° with the optical axes of the compensator. The refracting angle of the wedges is equal to Θ (Θ (a) The width of the fringe Ax;
(b) The magnitude and the sign of the optical path difference of ordinary and extraordinary rays, which appears due to the sample S.