Stokes I (top panels) and Q/I (bottom panels) profiles for the He II Ly-α line as a function of wavelength. The results are obtained with the unmagnetised FAL-C atmospheric model and for two LOSs, near the limb (μ = 0.1, left panels) and near the disc centre (μ = 0.9, right panels), respectively. Blue, red, and yellow lines correspond to CRD, PRD–AA, and PRD–AD calculations, respectively. The intensity is in units of number of photons per unit of surface, time, wavelength, and solid angle. The intensity profiles for PRD–AA and PRD–AD calculations overlap.