Uncertainty in measurements of the distances of scattering screens in pulsar observations

In our previous paper we investigated properties of the ionized interstellar medium in the direction of three distant pulsars: B1641–45, B1749–28 and B1933+16. We found that uniformly distributed scattering material cannot explain measured temporal and angular broadening. We applied a model for a thin scattering screen and found the distances to the scattering screens in all directions. In this paper, we consider more complicated models of scattering material distribution, such as models containing both a uniformly distributed medium and thin screen. Based on these models, we estimate the accuracy of localization of scattering screens and the possible relative contribution of each scattering component. (paper)