Problem 5.176

Using Huygens's principle, construct the wavefronts and the propagation directions of the ordinary and extraordinary rays in a positive uniaxial crystal whose optical axis (a) is perpendicular to the incidence plane and parallel to the surface of the crystal; (b) lies in the incidence plane and is parallel to the surface of the crystal; (c) lies in the incidence plane at an angle of \(45^{\circ}\) to the surface of the crystal, and light falls at right angles to the optical axis.