The Phase retardation in birefringent material is the shifting of the phase between two perpendicular polarization components of a light wave. Depending on the thickness of the crystal, light with polarization components along both axes with emerge in a different polarization state. The following formula is used: Gamma=(2piDeltanL)/lambda_0, where:
- Deltan = Change in the index of refraction
- L = thickness of the crystal
- lambda_0 = vacuum wavelength of light
References
The formula and defintion are from Wikipedia (https://en.wikipedia.org/wiki/Waveplate).
