Previous two-wavelength calculation algorithm technique must be implemented on the basis of the single-wavelength phase data. Here, we propose a new approach that combines ideas of moire'fringe theory and phase shifting interferometry. The patterns of two wavelengths are multiplied directly and filtered out the low frequency component to obtain the fringe pattern of equivalent wavelength. Then the phase of equivalent wavelength can be extracted by the conventional phase-step algorithm. Also, the algorithm can avoid the phase-step miscalibration introduced by traditional two wavelength phase shifting method.

© 2013 OSA

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