Reducing spatial coherence via dynamic scattering media enables aberration and speckle suppression in optical imaging
摘要
High-resolution optical imaging is limited by speckle noise and optical aberrations. Speckle, arising from interference of scattered fields, obscures fine detail and reduces contrast, while aberrations introduce spatially varying blur that is difficult to correct post hoc without additional complex instrumentation or postprocessing. To address these limitations, we show that placing a static sample in a dynamic scattering medium (DSM) produces a sequence of slightly different angular and phase-diverse views of the object. Averaging these views reduces the effective spatial coherence, suppressing speckle and reducing sensitivity to low-order aberrations and static phase-screen distortions with a small, predictable blur. A simple imaging model captures this behavior. Small random angular deviations and fine phase fluctuations introduced by moving scatterers average out as noise while contributing to blur. We further demonstrate that complex (field) averaging, after phase stabilization, provides higher contrast than intensity averaging. Simulations quantify the trade-off between speckle suppression and blur and agree with experiments in which we image a USAF resolution chart beneath a 250-µm mouse brain slice. Our method requires only repeated, independent views and is demonstrated in coherence-gated interferometric (Fourier-domain OCT) imaging. The mechanism is in principle applicable to other coherent imaging modalities capable of acquiring repeated, independent views. These findings suggest a pathway toward dynamic-diffuser-immersed objectives – optical elements that intrinsically suppress speckle and reduce sensitivity to low-order aberrations through controlled spatial-coherence modulation.