# Mueller calculus

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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.

## Introduction

Disregarding coherent wave superposition, any fully polarized, partially polarized, or unpolarized state of light can be represented by a Stokes vector ($\vec S$); and any optical element can be represented by a Mueller matrix (M).

If a beam of light is initially in the state $\vec S_i$ and then passes through an optical element M and comes out in a state $\vec S_o$, then it is written

$\vec S_o = \mathrm M \vec S_i \ .$

If a beam of light passes through optical element M1 followed by M2 then M3 it is written

$\vec S_o = \mathrm M_3 \big(\mathrm M_2 (\mathrm M_1 \vec S_i) \big) \$

given that matrix multiplication is associative it can be written

$\vec S_o = \mathrm M_3 \mathrm M_2 \mathrm M_1 \vec S_i \ .$

Matrix multiplication is not commutative, so in general

$\mathrm M_3 \mathrm M_2 \mathrm M_1 \vec S_i \ne \mathrm M_1 \mathrm M_2 \mathrm M_3 \vec S_i \ .$

## Mueller vs. Jones calculi

With disregard for coherence, light which is unpolarized or partially polarized must be treated using Mueller calculus, while fully polarized light can be treated with either Mueller calculus or the simpler Jones calculus. Many problems involving coherent light (such as from a laser) must be treated with Jones calculus, however, because it works with the electric field of the light rather than its intensity or power, and retains information about the phase of the waves.

More specifically, the following can be said about Mueller matrices and Jones matrices:[1]

Stokes vectors and Mueller matrices operate on intensities and their differences, i.e. incoherent superpositions of light; they are not adequate to describe neither interference nor diffraction effects.

...

Any Jones matrix [J] can be transformed into the corresponding Mueller–Jones matrix, M, using the following relation:

$\mathrm{M = A(T \otimes T^*)A^{-1}}$,

where * indicates the complex conjugate [sic], [A is:]

$\mathrm{A} = \begin{pmatrix} 1 & 0 & 0 & 1 \\ 1 & 0 & 0 & -1 \\ 0 & 1 & 1 & 0 \\ 0 & i & -i & 0 \\ \end{pmatrix}$

and ⊗ is the tensor (Kronecker) product.

...

While the Jones matrix has eight independent parameters [two Cartesian or polar components for each of the four complex values in the 2-by-2 matrix], the absolute phase information is lost in the [equation above], leading to only seven independent matrix elements for a Mueller matrix derived from a Jones matrix.

## Mueller matrices

Below are listed the Mueller matrices for some ideal common optical elements:

${1 \over 2} \begin{pmatrix} 1 & 1 & 0 & 0 \\ 1 & 1 & 0 & 0 \\ 0 & 0 & 0 & 0 \\ 0 & 0 & 0 & 0 \end{pmatrix} \quad$ Linear polarizer (Horizontal Transmission)
${1 \over 2} \begin{pmatrix} 1 & -1 & 0 & 0 \\ -1 & 1 & 0 & 0 \\ 0 & 0 & 0 & 0 \\ 0 & 0 & 0 & 0 \end{pmatrix} \quad$ Linear polarizer (Vertical Transmission)
${1 \over 2} \begin{pmatrix} 1 & 0 & 1 & 0 \\ 0 & 0 & 0 & 0 \\ 1 & 0 & 1 & 0 \\ 0 & 0 & 0 & 0 \end{pmatrix} \quad$ Linear polarizer (+45° Transmission)
${1 \over 2} \begin{pmatrix} 1 & 0 & -1 & 0 \\ 0 & 0 & 0 & 0 \\ -1 & 0 & 1 & 0 \\ 0 & 0 & 0 & 0 \end{pmatrix} \quad$ Linear polarizer (-45° Transmission)
$\begin{pmatrix} 1 & 0 & 0 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 0 & -1 \\ 0 & 0 & 1 & 0 \end{pmatrix} \quad$ Quarter wave plate (fast-axis vertical)
$\begin{pmatrix} 1 & 0 & 0 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 0 & 1 \\ 0 & 0 & -1 & 0 \end{pmatrix} \quad$ Quarter wave plate (fast-axis horizontal)
$\begin{pmatrix} 1 & 0 & 0 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & -1 & 0 \\ 0 & 0 & 0 & -1 \end{pmatrix} \quad$ Half wave plate (fast-axis vertical)
${1 \over 4} \begin{pmatrix} 1 & 0 & 0 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 1 & 0 \\ 0 & 0 & 0 & 1 \end{pmatrix} \quad$ Attenuating filter (25% Transmission)

## References

1. ^ Savenkov, S. N. (2009). "Light Scattering Reviews 4". p. 71. doi:10.1007/978-3-540-74276-0_3. ISBN 978-3-540-74275-3. |chapter= ignored (help) edit