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The Stokes I, Q, U and V parameters. The Stokes parameters are a set of values that describe the polarization state of electromagnetic radiation.They were defined by George Gabriel Stokes in 1851, [1] [2] as a mathematically convenient alternative to the more common description of incoherent or partially polarized radiation in terms of its total intensity (I), (fractional) degree of ...
Mueller calculus is a matrix method for manipulating Stokes vectors, which represent the polarization of light. It was developed in 1943 by Hans Mueller. In this technique, the effect of a particular optical element is represented by a Mueller matrix—a 4×4 matrix that is an overlapping generalization of the Jones matrix.
Degree of polarization (DOP) is a quantity used to describe the portion of an electromagnetic wave which is polarized. DOP can be calculated from the Stokes parameters. A perfectly polarized wave has a DOP of 100%, whereas an unpolarized wave has a DOP of 0%.
It is this vector-nature that considerably complicates the equation. Absorption will be different for each of the four components, moreover, whenever the radiation is scattered, there can be a complex transfer between the different Stokes components—see polarization mixing —thus the scattering phase function has 4*4=16 components.
An alternative and mathematically convenient description is given by the Stokes parameters, introduced by George Gabriel Stokes in 1852. The relationship of the Stokes parameters to intensity and polarization ellipse parameters is shown in the equations and figure below. =
The angle, , defines the rotation of the polarization axes between those defined for the Fresnel equations versus those of the detector. It can be used to correct for polarization mixing caused by a rotated detector, or to predict what the detector "sees", especially in the third Stokes component.
Areas where the degree of polarization is zero (the skylight is unpolarized), are known as neutral points. Here the Stokes parameters Q and U also equal zero by definition. The degree of polarization therefore increases with increasing distance from the neutral points. These conditions are met at a few defined locations on the sky.
Everything must interfere so that the second and third pictures agree; beam x has amplitude E and beam y has amplitude 0, providing Stokes relations. The most interesting result here is that r=-r’. Thus, whatever phase is associated with reflection on one side of the interface, it is 180 degrees different on the other side of the interface.