Overlapping speckle correlation algorithm for high-resolution imaging and tracking of objects in unknown scattering media

Abstract

Optical imaging in scattering media is important to many fields but remains challenging. Recent methods have focused on imaging through thin scattering layers or thicker scattering media with prior knowledge of the sample, but this still limits practical applications. Here, we report an imaging method named ‘speckle kinetography’ that enables high-resolution imaging in unknown scattering media with thicknesses up to about 6 transport mean free paths. Speckle kinetography non-invasively records a series of incoherent speckle images accompanied by object motion and the inherently retained object information is extracted through an overlapping speckle correlation algorithm to construct the object’s autocorrelation for imaging. Under single-colour light-emitting diode, white light, and fluorescence illumination, we experimentally demonstrate 1 μm resolution imaging and tracking of objects moving in scattering samples, while reducing the requirements for prior knowledge. We anticipate this method will enable imaging in currently inaccessible scenarios.

Depth-resolved imaging through dynamic scattering media via speckle cross-correlation under near-infrared illumination

“…Although the above methods exhibit flexibility, reliability, and high accuracy in phase modulation, they heavily rely on advanced light-field modulators such as spatial light modulators, deformable mirrors (DM), etc, thereby resulting in complex experimental setups or time-consuming algorithms. Benefiting from the 'optical memory effect' (OME) [21,22], the speckle correlation imaging (SCI) method [23][24][25][26] is found to be able to achieve the reconstruction of the image directly from the recorded speckle patterns, significantly reducing computational time and experimental complexity. The SCI methods include the speckle autocorrelation imaging (SAI) and the speckle cross-correlation imaging (SCCI) methods.…”