Abstract
In optical interferometers illuminated by laser sources the shift of the phase and changes in the curvature of the wave fronts lead to systematic errors, to which there must be added the error caused by misalignments. In the study described in the present article, the interference pattern was obtained from the actual amplitude and phase of the interfering wave fronts at the exit aperture of the interferometer. With reference to plane-wave illumination, the excess of the period of the output signal was obtained in a closed form in the case of small misalignment and negligible difference between the optical paths.