Fast and high-resolution multimode fiber speckle imaging via optical coherence control

Speckle imaging through single multimode fibers (MMFs) has garnered significant attention for its minimally invasive nature and high imaging resolution. However, the prevalent fully serial sampling approach severely limits imaging speed. Here, we propose, to our knowledge, a novel method for achieving fast and high-resolution speckle imaging via optical coherence control. Employing highly coherent input light, high-quality single-speckle patterns are generated to ensure superior image fidelity. Simultaneously, utilizing the incoherence between different input lights, incoherent hybrid speckle patterns are generated, enabling parallel sampling and thereby enhancing imaging speed. This method not only accelerates imaging but also preserves high-quality results. The experimental results indicate that by using high-quality hybrid speckle pattern illumination, the sampling speed increases Q-fold, with Q being the number of single speckle patterns within each hybrid speckle pattern. Reconstructed images exhibit structural similarity indices of at least 0.75 and peak signal-to-noise ratios of at least 15.5 dB. Additionally, we verified that the hybrid speckle pattern illumination method is also applicable to perturbation rejection MMF imaging systems. Our proposed method offers, to our knowledge, a novel approach to enhancing the performance of MMF speckle imaging systems.