Methods to produce polarised light.
(1) Polarisation by Reflection
(2) Polarisation by Scattering
(3) Polarisation by Double Refraction
Polarisation by Double Refraction:
There are some crystals like calcite and quartz of such type, when a ray of ordinary light is incident upon them, it breaks up into parts inside the cyrstal [figure], This phenomenon is known as double refraction. One of these two refracted rays, obeys the general laws of refraction and is called, ‘Ordinary-ray’ or ‘O-ray’ and the other do not obey the laws of refraction, is called ‘extra ordinary ray’ or ‘E-ray’. Both the rays are plane polarised in planes perpendicular to each other. In O-ray, the vibrations are in plane perpendicular to plane of incidence and in E-ray the vibrations are in plane of incidence. By any means, one of these two rays is removed so that plane polarised light may be obtained from the crystal.
