Examples - Birefringent wedge


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Example plot - the computed colors of a wedge of stressed plastic between crossed polars.

Pyxplot's built-in functions include a function for generating color objects which match the color of any given spectrum of light, specified as a function object which takes a wavelength as its single argument. A birefringent material is one, like stressed plastic, through which light travels at different speeds depending on its polarisation direction. That is, the material has a different refractive index depending upon the polarisation state of the light passing through it. When such a material is placed between crossed polars, an interference pattern is produced, which we plot here by writing down an expression for the spectrum of light emerging from the wedge after interference, as a function of the wedge's thickness.


set nokey
set nocolkey
set size 11 ratio 0.2
set noytics
set noylabel
spec(wl) = cos(2*pi*c1 / wl) * 1.25
set unit of length nm
set xlabel 'Optical path difference'
set colmap colors.spectrum(spec,1)
set sample grid 400x2
set c1range norenorm
set title 'Colors of a wedge of stressed plastic between crossed polars'
plot [unit(0*m):unit(2e-6*m)][0:1] x with colormap