Demodulation of a parabolic interferogram in time domain for rough surface characterization

Abstract

In this paper, a rough sample tested interferometrically by intermediate and high coherent red light is demodulated by the wavelet transform (WT) and Fourier transform (FT). The demodulated phase map resulting from the WT is unwrapped by the graph cuts method. A generic equation is given to simulate any parabolic carrier for reference phase map extraction. The unwrapped reference phase map from the simulated parabolic carrier is subtracted from the unwrapped total phase map from the experimental deformed parabolic interferogram to extract the phase map of the object being tested. It is shown that the uncertainty estimation is reduced by a factor of nine times as compared with that estimated through the FT when the intermediate coherent red light is used. Moreover, we observed a substantial decrease in the uncertainty estimation by a factor of 20 times as compared with that estimated through the FT when the high coherent red light is used. We claim that the decrease in uncertainty estimation is likely due to the negligible side lobes effect in phase-contrast image.