PLL interferometry on non-continuous domains

The phase-locked loop technique (PLL) is a fast demodulating scheme recently adapted to carrier fringe pattern analysis. The main advantage of the phase-locked loop is that the phase extraction and the unwrapping process are performed simultaneously. One drawback of the PLL is its path dependent phase demodulation. This means that even noise free fringe patterns containing holes of invalid data cannot be successfully detected. The work presented here extends the validity of the phase locked loop, allowing its use with connected regions of valid fringe data having any shape. The extended method was tested and implemented numerically and experimentally.