Random Error Reduction in Phase Shift Interferometry

The object of research in this article is a new approach to reducing the error of phase demodulation in phase-shifting interferometry. It is based on averaging a combination of functionally related sequences of interference patterns intensities, with the help of which the phase is demodulated. It is possible to average both individual phase values at separate points of the interference pattern and their differences between different points. The method is based on finding the phase difference at three arbitrary points of the interference pattern. Fixing one or two points of the interference pattern with other points, scanning is carried out over its entire surface. Thus, the authors obtain a set of phase differences between different points. Averaging them allows to reduce the influence of noise on the measurement result. Thus, for each point of the interference pattern, a set of phase values or phase differences is obtained. Using the found phase differences, it is also possible to determine the phase directly at each point of the interference pattern. In contrast to the known methods, the proposed approach does not require registration of additional interference patterns. This allows to shorten the measurement time without losing their accuracy.