The properties of a light beam passed through an NLC layer with positive orientational nonlinearity and then reflected from the NLC-substrate interface have been experimentally studied. The divergence and the intensity profile of this beam were found to be quite different from those of the beam transmitted through the NLC cell. It is shown that the aberrational pattern in the cross-section of the reflected beam and the dynamics of its formation can be used to study the orientational nonlinearity even in the presence of thermal effects.