Application of the Fourier analysis methods to the three beam interferometry

In this paper, method for enhancing the measurement capability of an optical vortex interferometer is proposed. We adapted the techniques used in the carrier frequency interferometry to describe a way of measuring the change of the object's beam propagation direction and of reconstructing the geometry of its wavefront. To do this the interference field of the three beam interferogram and its Fourier spectrum has been calculated. The experimental results obtained with the presented technique are in agreement with the results obtained by using the analysis applied to the optical vortex interferometer. The proposed method does not require any alterations in the optical vortex interferometer body. The calculations are performed on the single three-beam interferogram which is fundamental for the optical vortex interferometry. In this way we take advantage of both, the carrier frequency as well as the optical vortex interferometry.

► We proposed Fourier techniques to the analysis of the three-beam intereferogram.
► We calculated Fourier spectrum from the three beam intefrerograms (analytically and from the experimental interferogram).
► We showed that the presented method and methods used in our previous analysis are complementary.