Vol. 49, Issue 2, pp. 331-343
dual-wavelength interferometry, two-step phase shifting interferometry, blind phase shift, surface relief retrieval, areal surface roughness, areal waviness, phase map
The new two-step dual-wavelength interferometry method that uses only two pairs of interferograms for surface relief retrieval is proposed. In this method, two interferograms in each pair are differed only by an arbitrary phase shift of a reference wave. The method allows using only one out-of-plane shift of a reference wave to record each second interferogram in both pairs, since arbitrary phase shifts between interferograms in each pair can be defined by calculation of the correlation coefficient between two interferograms. This method can extract separately areal surface roughness and areal waviness phase maps from a phase map of the total surface relief and reduce errors produced during the surface relief retrieving. Computer simulation and experimental verification have confirmed the reliability of the proposed method.