Layered phase restoration method for dual-wavelength digital holographic microscopy based on linear programming

Dual-wavelength digital holographic microscopy is a method to acquire surface topography of high-depth samples, offering a broader depth range compared to single-wavelength technique. When applying to high aspect ratio structures, however, optical aberrations are difficult to remove, resulting in phase restoration distortions. To address this limitation, we developed a layered phase restoration method for DW-DHM. This approach restores the phase by decomposing the step structure into layers and applying a targeted de-aberration process at each layer, followed by precise dual-wavelength phase unwrapping through linear programming algorithm (LPA). Simulations and experimental results show that, while preserving the noise robustness of LPA, the proposed method provides significantly enhanced resistance to various aberrations. For topographic measurements of complex micro-nano scale step structures, this approach effectively mitigates the issue in LPA where the phase restoration affected by hard-to-eliminate aberrations, demonstrating its potential for advanced applications in micro-nano device measurement.