Propagation Of Light Through Birefringent Crystal

Case IV In this final case let us consider the optics axis to be in the plane of incidence but is along the direction as shown by the broken lines in fig 6. let us consider a plane wave AB incident normally on such interface. The s wave will propagate normal with the refractive index n_o and the wave front corresponding to this polarization will remain un deviated inside the crystal as shown by OO' . This is the ordinary ray But for the in plane p wave the wave front is elliptical as shown in the fig. 4. This wave front can be obtained by plotting an ellipse having center at C or D with major axis to the optics axis having magnitude c/ n_e and the minor axis as c/n_o . It is obvious from this Hugenn's construction that the p wave will under go a deviation and corresponding wave front is denoted by EE'. Hence under such case the two waves will split into two components even under normal incidence, one of them following the undeviated path termed as ordinary wave and the other under going deviation is termed as extraordinary ray.

Next lecture will demonstrate how to use such properties of uniaxial crystal to generate the wave of required polarization froma plane polarized light.

Fig.4 : Propagation of plane wave in uniaxial crystal when optics axis is in the plane of incidence but oriented at certain angle with respect to the interface.