“…Although previous works have successfully reproduced most of the features observed in a variety of laser spectroscopy systems [1,3,4,23,24], in their theoretical analyzes the authors of these works make the usual approximations which are equivalent to neglecting the intensity of the probe beam. In this work we avoid making these approximations and, by comparison both with experimental results and with previous works [9] we show the effect of the probe beam intensity on the features of the corresponding spectra. This model can also be applied to the copropagating polarized VSOP spectroscopy and we present new experimental spectra for this configuration, which complements the counterpropagating measurements previously reported in [9].…”