Phase Shift Strategies in Phase Shifting Time Averaging Interferometry

Abstract

Classical time-averaging interferometry technique is widely used for MEMS/MOEMS dynamic behavior investigations. It provides useful information on resonant vibration frequencies and mode shapes in the form of Bessel fringe images. To evaluate the information on objects’ vibration amplitude distribution, one needs to further process Bessel fringe images (besselograms). Among different available approaches to besselograms processing, Temporal Phase Shifting is of particular interest since it provides the most accurate results. However, it requires an additional cumbersome correction routine via specially designed look-up-tables fitted to the calculation algorithm used. In this paper, we numerically investigate the possibility of reducing Bessel images argument (phase) evaluation error by different phase shifting strategies. Two different 5 step algorithms are investigated for that purpose. Additionally, a quick and robust correction procedure based on evaluated phase distribution is presented. It allows us to speed up the calculations significantly. Moreover, such an approach is much less susceptible to noise in comparison to a look-up-table solution.