In phase-shifting interferometry (PSI), a set of interferograms with a known phase step displacement is necessary, but incorrect calibration deviation errors can occur in shifter devices. We present a method to recover the phase distribution in the presence of this deviation error through the widely used PSI technique. By applying the radon transform as a profile measurement, our algorithm first estimates the deviations in the phase steps, then these calculations are used to obtain the wrapped phase using the Hough transform as an estimation of coefficients in sinusoidal patterns. Simulation and experimental results have shown good performance. The results reveal that this algorithm is able to detect and decrease the phase error due to miscalibrations.
In optical interferometry are several optimization methods applied to estimate the phase of a closed fringe pattern. There are several optimization techniques which play an important role in finding the phase interferogram parameters. In this work, a Genetic Algorithm in combination with Frequency guided Sequential Demodulation are implemented to estimation the phase of synthetic fringe pattern. The method gives good results in demodulation of closed fringe patterns. Results in processing time are similar to traditional optimization techniques, but the method presents computer simplifications to others algorithms.
The phase shifting algorithms are a widespread method in the technical and scientific literature for relatively noninvasive measurements of a variety physical variables. PSI (phase-shifting interferometry) techniques consist in acquiring at least three interferograms to obtain the wrapped phase. It is important to emphasize that if these acquired intensity images are inadequate, the measurement would have an error associated. The presence of miscalibration or mechanical vibrations in an interferogram can cause an inaccurate measurement; it is possible to design a phase shifting algorithm with a better performance. The present work proposes a novel methodology in order to determine the existence of a miscalibrated interferogram in a four steps phase shifting algorithm by applying the Radon transform.
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