Applied Optics · 1993 · 684 citations · 6 references
EngineeringPhase ErrorsPhase MapsInterferometryDigital HolographyCalibrationComputational ImagingRadiologyHealth SciencesCartographyMedical ImagingSynthetic Aperture RadarMedical Image ComputingNew AlgorithmPhase RetrievalTemporal Phase-unwrapping AlgorithmRadarBiomedical ImagingQuantitative Phase Imaging
Existing 2‑D phase‑unwrapping algorithms detect 2π discontinuities in a single phase map, but noise can cause error propagation that corrupts the image. The paper proposes a new algorithm that unwraps interferometric phase maps by performing one‑dimensional unwrapping along the time axis. The algorithm unwraps phase by sequentially processing incremental phase maps along the time axis, applicable to interferometry where a series of incremental maps leads to the final phase‑difference map, such as in quasi‑static deformation analysis. The algorithm is simple, confines phase errors to high‑noise regions, correctly unwraps phase maps with global discontinuities when their positions are fixed over time, and enables real‑time unwrapping.
A new algorithm is proposed for unwrapping interferometric phase maps. Existing algorithms search the two-dimensional spatial domain for 2π discontinuities: only one phase map is required, but phase errors can propagate outward from regions of high noise, corrupting the rest of the image. An alternative approach based on one-dimensional unwrapping along the time axis is proposed. It is applicable to an important subclass of interferometry applications, in which a sequence of incremental phase maps can be obtained leading up to the final phase-difference map of interest. A particular example is quasi-static deformation analysis. The main advantages are (i) it is inherently simple, (ii) phase errors are constrained within the high-noise regions, and (iii) phase maps containing global discontinuities are unwrapped correctly, provided the positions of the discontinuities remain fixed with time. The possibility of real-time phase unwrapping is also discussed.
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Noise-immune phase unwrapping algorithm
J. M. Huntley · Applied Optics · 1989 · 321 citations
Fourier fringe analysis: the two-dimensional phase unwrapping problem
Donald J. Bone · Applied Optics · 1991 · 286 citations