State three methods of polarizing an unpolarized light

Answer Details

Three methods of polarizing an unpolarized beam of light are:

1. Polarization by reflection - when ordinary light is reflected from a transparent surface (for example water or glass) at the polarizing (Brewster) angle, the reflected light becomes plane polarized.
2. Polarization by selective absorption (using a polaroid/dichroic material) - a polaroid sheet transmits vibrations in only one plane and absorbs those in all other planes, producing plane polarized light.
3. Polarization by double refraction (using a doubly-refracting crystal such as calcite/Nicol prism) - the crystal splits the light into two plane polarized rays vibrating in mutually perpendicular planes.

(Polarization by scattering, as occurs with sunlight in the atmosphere, is also acceptable.)