The Stokes parameters are a set of values that describe the polarization state of electromagnetic radiation

Electromagnetic radiation

Electromagnetic radiation is a form of energy that exhibits wave-like behavior as it travels through space...

. They were defined by George Gabriel Stokes

George Gabriel Stokes

Sir George Gabriel Stokes, 1st Baronet FRS , was an Irish mathematician and physicist, who at Cambridge made important contributions to fluid dynamics , optics, and mathematical physics...

 in 1852, as a mathematically convenient alternative to the more common description of incoherent

Coherence (physics)

In physics, coherence is a property of waves that enables stationary interference. More generally, coherence describes all properties of the correlation between physical quantities of a wave....

 or partially polarized radiation in terms of its total intensity

Field strength

In physics, the field strength of a field is the magnitude of its vector value.In theoretical physics, field strength is another name for the curvature form...

 (I), (fractional) degree of polarization

Degree of polarization

Degree of polarization is a quantity used to describe the portion of an electromagnetic wave which is polarized. A perfectly polarized wave has a DOP of 100%, whereas an unpolarized wave has a DOP of 0%. A wave which is partially polarized, and therefore can be represented by a superposition of...

 (p), and the shape parameters of the polarization ellipse.
The relationship of the Stokes parameters to intensity and polarization ellipse parameters is shown in the equations below and the figure at right.


Here , and are the spherical coordinates of the three-dimensional vector of cartesian coordinates .