Fasevisninger

Fasevisninger, often translated as phase unwrapping, is a crucial process in many fields that analyze periodic phenomena, particularly in signal processing and imaging. It deals with the ambiguity inherent in phase measurements, where the phase angle of a signal is only known modulo 2π. This means that if a signal has a phase of 3π/2, it is indistinguishable from 7π/2 or -π/2 based solely on the raw measurement.

The goal of fasevisninger is to reconstruct the true, continuous phase by adding or subtracting multiples of 2π to the observed, wrapped phase. This is essential for accurate analysis, as many algorithms and interpretations rely on the absolute phase rather than its wrapped representation. For instance, in interferometry, the phase difference between two signals directly relates to the distance or deformation. If the phase is wrapped, the calculated distance would be incorrect, potentially by multiples of the wavelength of the light used.

Common methods for fasevisninger include path following algorithms, where the unwrapping proceeds along a connected path in the phase map. Another approach is based on minimizing the phase difference between adjacent pixels, assuming a smooth underlying phase. More advanced techniques employ statistical methods or consider the coherence of the signal to reliably determine the correct phase. The success of fasevisninger often depends on the quality of the wrapped phase data and the absence of significant noise or discontinuities that could lead to unwrapping errors.