Digital dynamic-fringe pattern processing without frequency carrier, using wideband phase-shifting algorithmsM

Abstract

Here, we will show a method to recover the phase of a temporal sequence of interferograms, without knowing its carrier frequency. To accomplish this, we will use algorithms that we call wideband phase-shifting algorithms. The underlying idea is to combine first and second order quadrature filters to obtain wideband phase-shifting algorithms. This first and second order quadrature filters are analogous to the first and second order filters commonly used in communications engineering. The method presented here is very useful in areas where transient events are analised, and a high performance demodulation method is needed to recover the phase of the interferograms without frequency carrier, i.e., when one does not know the phase shift or the frequency carrier. In general, the approach presented here gives a powerful and robust frequency analysis and design tool for detuning phase-shifting algorithms for interferometry.