Breaking the speed-resolution trade-off in 3.3-km non-line-of-sight imaging using scanning-free laser reflective tomography

Non-line-of-sight (NLOS) imaging, which allows the recovery of hidden scenes outside the direct view, holds immense potential across numerous fields. However, conventional scanning-based NLOS imaging systems, face a fundamental trade-off between imaging speed and resolution due to their reliance on scanning relay surfaces, where dense sampling prolongs measurement. Here, we introduce a scanning-free NLOS imaging technique that adapts laser reflective tomography (LRT) to reconstruct hidden objects by exploiting the diffuse relay surface as a natural beam expander. Our method requires only single-point detection of third-bounce photons, effectively breaking through the resolution and speed limitations imposed by scanning. Compared with scanning-based approaches, it delivers a twofold enhancement in spatial resolution and a 91-fold improvement in imaging speed. Furthermore, we extend the advantages of this method to long-range experiments, demonstrating NLOS imaging over 3.3 km with a resolution of 3 cm in 3 minutes, establishing new benchmarks in imaging range, resolution, and speed for NLOS imaging.