 For a half-wave plate, the relationship between "L", Δ"n", and λ0 is chosen so that the phase shift between polarization components is Γ = π.Now suppose a linearly polarized wave with polarization vector formula_2 is incident on the crystal.Let θ denote the angle between formula_2 and formula_4, where formula_4 is the vector along the waveplate's fast axis.