Carrier fringes by axial translation of the first lens in a double aperture common-path interferometer

Abstract

This paper presents a method for introducing carrier fringes in a double-aperture common-path interferometer. By using the Fresnel diffraction theory, we demonstrated that the axial displacement of the first lens of the 4f optical system involved is linearly proportional to the carrier frequency introduced in the interferogram (both for positive or negative values) in a wide range. Because this displacement is of the order of centimetres, its experimental generation is very simple, practical, and with acceptable accuracy, being carried out by means of a non-sophisticated system. A theoretical model and experimental results are shown.