Single-Shot Dual-Wavelength Lens-Free Digital Holography Enabled by Polarization Multiplexing

Lens-free digital holography (LFDH) provides a compact and large field of view platform for quantitative phase imaging. However, inline configurations inherently suffer from twin-image artifacts and typically require multi-height acquisition, wavelength switching, or temporal phase-shifting schemes for reliable phase retrieval. In this work, we propose a single-shot polarization-multiplexed dual-wavelength inline lens-free holography framework for isotropic or weakly polarization-sensitive samples. Two coherent light sources with orthogonal linear polarization states are coaxially combined to simultaneously illuminate the sample, while a polarization-resolved image sensor encodes wavelength information at the pixel level without spectral filtering. Through polarization demultiplexing and subpixel spatial registration, two wavelength-resolved holograms are reconstructed from a single exposure. An iterative dual-wavelength phase retrieval algorithm incorporating cross-wavelength constraints is then employed to suppress twin-image artifacts and recover the object phase without wavelength switching, mechanical scanning, or temporal phase modulation. The proposed approach enables single-frame phase reconstruction while preserving the structural simplicity and wide-field imaging capability of inline LFDH. Experimental results demonstrate effective twin-image suppression and improved phase retrieval performance, highlighting the potential of the method for wide-field and dynamic-compatible phase imaging of weakly polarization-sensitive specimens.