Department of Applied Physics, The Hebrew University of Jerusalem, Jerusalem, 9190401, Israel.
Nat Commun. 2019 Jul 26;10(1):3343. doi: 10.1038/s41467-019-11279-6.
Optical imaging through diffusive, visually-opaque barriers and around corners is an important challenge in many fields, ranging from defense to medical applications. Recently, novel techniques that combine time-of-flight (TOF) measurements with computational reconstruction have allowed breakthrough imaging and tracking of objects hidden from view. These light detection and ranging (LiDAR)-based approaches require active short-pulsed illumination and ultrafast time-resolved detection. Here, bringing notions from passive radio detection and ranging (RADAR) and passive geophysical mapping approaches, we present an optical TOF technique that allows passive localization of light sources and reflective objects through diffusive barriers and around corners. Our approach retrieves TOF information from temporal cross-correlations of scattered light, via interferometry, providing temporal resolution that surpasses state-of-the-art ultrafast detectors by three orders of magnitude. While our passive approach is limited by signal-to-noise to relatively sparse scenes, we demonstrate passive localization of multiple white-light sources and reflective objects hidden from view using a simple setup.
通过漫射、视觉不透明的障碍物和拐角进行光学成像是许多领域的一个重要挑战，从国防到医疗应用都有涉及。最近，一些新的技术将飞行时间（TOF）测量与计算重建相结合，从而实现了对隐藏在视线之外的物体的突破性成像和跟踪。这些基于光探测和测距（LiDAR）的方法需要主动短脉冲照明和超快时间分辨检测。在这里，我们借鉴了无源无线电探测和测距（RADAR）以及无源地球物理测绘方法的概念，提出了一种光学 TOF 技术，该技术允许通过漫射障碍物和拐角被动定位光源和反射物体。我们的方法通过干涉测量从散射光的时间互相关中恢复 TOF 信息，提供了比最先进的超快探测器高出三个数量级的时间分辨率。虽然我们的无源方法受到信号噪声的限制，只能应用于相对稀疏的场景，但我们使用简单的设置演示了对隐藏在视线之外的多个白光光源和反射物体的被动定位。
