Polarisation is a phenomenon generated by the oscillation of light waves restricted to a single plane.
In an ordinary beam of light with millions of waves, the light vectors of component waves will remain in all possible directions on a plane drawn at right angles to the direction of propagation.
This happens so due to random orientations of excited atoms or molecules in the source.
Such an ordinary beam of light with the electric vectors arranged symmetrically about the direction of propagation is called an unpolarised light.
We may assume all these vibrations to be resolved into two rectangular components of equal amplitude but having a relative phase difference that varies rapidly and randomly.
Now, if by some means one of these rectangular vibrations is cut off we get vibrations of all the component waves confined in one definite direction.
Such light is said to be plane polarised light.
When a beam of light is formed via many mechanisms (reflection, refraction, or dispersion) when vibration is limited to one very efficient aircraft, it is referred to as far-flung polarised light.
Polarisation can be divided into three categories: plane of polarised light, polarization in a circle, and elliptical polarisation.