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Nature Photonics

Non-line-of-sight (NLOS) imaging is a rapidly developing research direction that has significant applications in autonomous vehicles, remote sensing and other areas. Existing NLOS methods primarily depend on time-gated measurements and sophisticated signal processing to extract information from scattered light. Here we introduce a method that directly manipulates light to counter the wall’s scattering. This method, termed unseen non-line-of-sight casted optical aperture visibility-enhanced return (UNCOVER) focusing, operates by actively focusing light onto the hidden target using wavefront shaping. By raster scanning that focus, we can actively image the hidden object. The focus thus formed is near diffraction limited and can be substantially smaller than the object itself, thereby enabling us to perform NLOS imaging with unprecedented resolution. We demonstrate that a resolution of ~0.6 mm at a distance of 0.55 m is achievable in UNCOVER, giving us a distance-to-resolution ratio of ~970. An imaging scheme that employs raster-scanned active focusing can image hidden, non-line-of-sight objects

High-resolution non-line-of-sight imaging employing active focusing