Phase recovery from interferograms under severe vibrations

A phase recovery procedure from several interferograms acquired in highly noisy environments as severe vibrations is described. This procedure may be implemented when phase shifting techniques may not be applicable due to the high error in the phase shift due to the vibrations. The phase differences among successive interferograms may contain nonlinear terms that could lead a sign changes in the supposed constants shift terms among acquired images. This can not be handled correctly with algorithms that corrects small nonlinearities in the phase shifts due to moderate disturbances during the phase shifting process. In most interferometric configurations for phase measurements the main effect of vibrations is to introduce a misalignment in the interferometric setup. Then, the phase differences between each interferogram may contain piston, tilt, and defocus errors. We observed that the tilt term is often the most dominant of the phase differences terms. In such cases, cosine of the phase differences among interferograms may be recovered. This cosine may be processed with Fourier methods in order to recover the phase differences. Once the phase differences are available the phase encoded in the interferograms may be determined. The proposed algorithm is tested in real interferograms. © 2013 SPIE