Beam pattern models for a hollow column with a halo of scattered radiation on the neutron star surface. θ has the same meaning as in Fig. 8. The minimum is produced when observer looks in the direction of the accretion stream. Left: fixed column thickness α_o − α_i = 0.06 rad and different opening angles α_o = 0.2 rad (solid line), α_o = 0.15 rad (dashed line), α_o = 0.1 rad (dotted line). Right: fixed outer opening angle α_i = 0.1 rad and different column thickness α_o − α_i = 0.02 rad (solid line), α_o − α_i = 0.04 rad (dashed line) and α_o − α_i = 0.06 rad (dotted line).