code: def _reduced2physical_deflection(self, alpha_reduced, idex_lens):
          
          factor = self._reduced2physical_factor[idex_lens]
          #factor = self._cosmo_bkg.D_xy(0, z_source) / self._cosmo_bkg.D_xy(z_lens, z_source)
          return alpha_reduced * factor
docs: alpha_reduced = D_ds/Ds alpha_physical
  
          :param alpha_reduced: reduced deflection angle
          :param z_lens: lens redshift
          :param z_source: source redshift
          :return: physical deflection angle