Enhanced multi-wavelength coherent diffractive imaging via gradient-based probe-object decoupling using single-shot RGB acquisition

Abstract Coherent diffractive imaging (CDI) reconstructs object complex amplitudes from diffraction patterns using iterative phase retrieval algorithms, while multi-wavelength CDI (MW-CDI) improves reconstruction robustness through wavelength diversity. However, practical MW-CDI systems remain affected by probe-object coupling, non-uniform illumination, and sequential acquisition instability, leading to probe-related reconstruction artifacts. To address these limitations, a single-shot RGB MW-CDI framework combined with a gradient-based probe-decoupling reconstruction strategy is proposed. An RGB laser source and a color CCD camera are employed to simultaneously acquire diffraction patterns at three wavelengths, thereby reducing temporal instability associated with sequential acquisition. An illumination-weighted gradient update strategy is further incorporated into the iterative framework to suppress residual probe-related artifacts caused by non-uniform illumination. Numerical simulations and experimental results demonstrate improved reconstruction fidelity, faster convergence, and enhanced robustness compared with conventional MW-CDI reconstruction. Experimental imaging of a USAF1951 target and weakly absorbing biological samples further verifies the effectiveness of the proposed method for stable and high-precision multi-wavelength lensless imaging.