Edge memory effect for hidden object tracking

Tracking objects through a scattering medium is highly desirable. As many recent advances have shown, non-invasive imaging and tracking in real-time can be achieved by utilizing optical memory effect for speckle correlations. Limited by the memory effect range, this method however works only for tiny objects, which reduces its popularity in tracking applications where the object is sizable but only its trajectory, not its image, is important. In this work, we show that the difference of speckle images is still correlated even when the moving object’s size is beyond the memory effect range. We have experimentally demonstrated the successful tracking of the hidden moving object, with its sizes exceeded the memory effect range. Our proposed technique requires a standard camera only, with no need to adopt other hardware techniques such as wavefront shaping, laser illuminated detection, or interferometric detection, hence is appealing for hidden object tracking in real-world applications.