Robust and fast dual-wavelength phase unwrapping in quantitative phase imaging with region segmentation

Dual-wavelength digital holographic microscopy extends the unambiguous measurement range in quantitative phase imaging. However, it suffers from increased noise, which reduces phase sensitivity, especially when a larger beat wavelength is synthesized. We present a simple, robust, and fast dual-wavelength phase unwrapping method, without increased phase noise, by segmenting a single wavelength phase map into multiple regions along its phase discontinuities and calculating the fringe order of each region. The method works properly with a large beat wavelength, while reducing phase noise to the level of a single wavelength. Simulations were performed for imaging a smooth profile sample and a multi-heights step. We also demonstrated its practical implementation in quantitative imaging of microstructures where a beat wavelength was up to 20 . 475 μ m . • Dual-wavelength phase unwrapping for DHM is presented with region segmentation. • The method is simple, fast and robust. • A beat wavelength of 20 . 475 μ m using two lasers is achieved.