Answer to Question #90074 in Optics for Shivam Nishad

Question

Explain the term birefringence. Explain how is unpolarised light incident on a uniaxial crystal polarised ? Draw o-and e-wave surfaces in a negative uniaxial crystal.

Answer 1

Birefringence - the effect of splitting the beam during the passage of anisotropic media on two composes: ordinary (o) and the extraordinary (e),

In uniaxial crystals, there is a preferred direction along which the ordinary and extraordinary components propagate without being separated spatially and with the same speed. The direction in which no double refraction is observed is called the optical axis of the crystal. The plane passing through the optical axis of the crystal is called the main section.

Ordinary and extraordinary rays are completely plane-polarized in mutually perpendicular directions. Oscillations of the electric field strength vector in an ordinary wave occur in the direction perpendicular to the main cross section of the crystal for an ordinary ray. In an extraordinary wave, the oscillations of the intensity vector occur in a plane that coincides with the main section for an extraordinary ray.

If one of the rays is strongly absorbed, then at the output you can get one beam with linear polarization. This phenomenon is called dichroism.