Keywords

Phase, demodulation, unwrapping, algorithm, diffraction, interference, interferogram, fringe pattern.

Abstract

In this thesis we present a set of phase recovery alternatives. We begin with theoretical antecedents of the phenomenon of interference and diffraction. We present the phenomenon of diffraction together with Fourier theory and the general idea of phase recovery. Then, phase recovery by diffraction takes place, with the theoretical explanation of the functionality of the thin lens within a 4f optical system and the Gerchberg-Saxton algorithm, which are so completely related. The efficiency of the algorithm is then shown with examples of simulations. As an extra contribution, an experimental evaluation is made using intensity measurements, presenting obstacles in the direct execution of the algorithm.

Subsequently, the phase recovery by interference is studied showing the estimation of the background light which is the main drawback for some recovery methods by the interference phenomenon. We also present five methods which, in order of interest, are Takeda, Brunning, Greivenkamp, Gram-Schmidt, and minimization of the coefficient of variation. It is the last method to which was found a greater contribution to the phase recovery by interference problem , since it is efficient under experimental complications and computational processing.

The phase recovery methods addressed were analyzed in detail with their respective computational simulation. Additionally, an experimental evaluation of the method of minimization of the coefficient of variation is carried out using two interferograms. Throughout the presentation of the phase recovery methods by interference, the unwrapped phase is used, that is why its theoretical development is included.

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