Fourier-transform method of phase-shift determination

A new phase-shifting interferometry analysis technique has been developed t o overcome the errors introduced by nonlinear, irregular, or unknown phase- step increments. In the presence of a spatial carrier frequency, by observa tion of the phase of the first-order maximum in the Fourier domain, the glo bal phase-step positions can be measured, phase-shifting elements can be ca librated, and the accuracy of phase-shifting analysis can be improved. Furt hermore, reliance on the calibration accuracy of transducers used in phase- shifting interferometry can be reduced; and phase-retrieval errors (e.g., f ringe print-through) introduced by uncalibrated fluctuations in the phase-s hifting phase increments can be alleviated. The method operates determinist ically and does not rely on iterative global error minimization. Relative t o other techniques, the number of recorded interferograms required for anal ysis can be reduced. (C) 2001 Optical Society of America.