We report on the theoretical analysis of a detector type influence on the normal deflection signal in photothermal experiments. Two cases are examined. In the first, the quadrant photodiode was considered as the detector; in the second the signal from the position detector, which measures the central moment displacement of the probe beam, was analyzed. Both analyses were carried out within the framework of the complex ray theory. The normal photodeflection signal was found to depend on the type of detector used in the photothermal deflection experiments for some parameters of its setup.