Carrier frequency by axial displacements of lens and grating in a double-aperture common-path interferometer

Abstract

Double-aperture common-path interferometer (DACPI) is built on a 4f optical imaging system. It consists of two lenses, two apertures at input plane, and a grating at Fourier plane. As known, a carrier frequency is introduced when first lens or grating is displaced axially. Nevertheless, the effect when both displacements are present is not described yet. In this manuscript, we describe the interrelation existing among the axial displacements of the first lens and, grating. Additionally, with least squares method, we find with high accurate the initial position of the first lens and grating, for calibrating the 4f optical system. It is important to note that no tilt between the two beams is requested to produce this effect, and it turns out to be simpler, and more accurate than other existing methods. This proposal will be discussed and illustrated in detail with experimental results.