Application of phase unwrapping algorithm based on least-squares and iteration in digital holography

Phase unwrapping is an important content of digital holography, which gets continual and real phase from wrapped phase. The least-squares phase unwrapping is a fast and effective method. But for wrapped phases with complicated variation and much noise, the unwrapped phase got by least-squares method will produce errors. In this paper iterative unwrapping of phase difference is combined with least-squares unwrapping to eliminate the errors. This method is used in digital holography to unwrap phases with complicated variation. The phase variation of object wave through a polymethyl methacrylate (PMMA) specimen with a hole under uniform tensile force is measured by holography. The phase is unwrapped by phase unwrapping based on least-squares and iteration. The cosine patterns of unwrapped phase and wrapped phase are consistent. Which means this method is correct and can be used to unwrap phases with complicated variation and much noise.