Polariser
A linear polariser passes the light polarised along its transmission axis and absorbs the rest. Rays pass straight through; their power falls by Malus's law.
The model
A polariser is a thin plane across the beam. With its transmission axis at \(\theta\) from p, it projects the Jones vector \((E_p, E_s)\) onto that axis:
\[J(\theta) = \begin{pmatrix} \cos^2\theta & \cos\theta\sin\theta \\ \cos\theta\sin\theta & \sin^2\theta \end{pmatrix}.\]At 0° it passes p, and at 90° it passes s. Linear light at an angle \(\phi\) to the axis keeps the share
\[\frac{P_\text{out}}{P_\text{in}} = \cos^2\phi\]of its power (Malus’s law). Unpolarised light, two launches s and p, keeps half.
The matrix acts on each ray and on each sample of the diffracted field.
A polariser rolled about its normal by its Roll \(\rho\) turns its axis with it, as a waveplate does: at \(\theta\) rolled \(\rho\), it acts as one at \(\theta - \rho\) for light along its normal. Rolled \(90°\), a polariser along p passes s. One rolled with a rolled source passes all of its light.
Settings
| Field | Default | Meaning |
|---|---|---|
length | 25.4 | mm aperture. |
axis | 0 | degrees: the transmission axis from p (0 passes p, 90 passes s). |
From the tool's own tables, file format version 1: the names are those in a .jekray file.
Assumptions
- The polariser is ideal: it passes all of the light along its axis and none across it. For a finite extinction ratio, use a polarising beam splitter with its leakage set, or a crystal polariser.
- It has no thickness, and works at every wavelength and angle alike.