Real-time scan-free non-line-of-sight imaging

Real-time non-line-of-sight imaging is crucial for practical applications. Among existing methods, transient methods present the best visual reconstruction ability. However, most transient methods require a long acquisition time, thus failing to deal with real-time imaging tasks. Here, we provide a dual optical coupling model to describe the spatiotemporal propagation of photons in free space, then propose an efficient non-confocal transformation algorithm and establish a non-confocal time-to-space boundary migration model. Based on these, a scan-free boundary migration method is proposed. The data acquisition speed of the method can reach 151 fps, which is ∼7 times faster than the current fastest data acquisition method, while the overall imaging speed can also reach 19 fps. The background stability brought by fast scan-free acquisition makes the method suitable for dynamic scenes. In addition, the high robustness of the model to noise makes the method have the capability of non-line-of-sight imaging in outdoor environments during the daytime. To further enhance the practicality of this method in real-world scenarios, we exploit the statistical prior and propose a plug-in-and-play super-resolution method to extract higher spatial resolution signals, reducing the detector array requirement from 32 × 32 to 8 × 8 without compromising imaging quality, thus reducing the device expense of detectors.