Fractional residual for different ratios I_⊥/I_s and different HWP spinning frequencies. Each column shows a different f_s value and each row a different I_⊥/I_s ratio. A thinner HWP, I_⊥/I_s → 0.500, has beats in the intensity over an extended period and a thicker HWP has shorter beats. By looking at the figure from left to right, it is clear that the spinning speed compresses the beats. The maximum amplitude remains the same because it only depends on θ₀, which is fixed to 1° in this particular simulation.