Passive sensing around the corner using spatial coherence

Abstract

When direct vision is obstructed, detecting an object usually involves either using mirrors or actively controlling some of the properties of light used for illumination. In our paradigm, we show that a highly scattering wall can transfer certain statistical properties of light, which, in turn, can assist in detecting objects even in non-line-of-sight conditions. We experimentally demonstrate that the transformation of spatial coherence during the reflection of light from a diffusing wall can be used to retrieve geometric information about objects hidden around a corner and assess their location. This sensing approach is completely passive, assumes no control over the source of light, and relies solely on natural broadband illumination.

Passive optical time-of-flight for non line-of-sight localization

“…The presented technique is conceptually similar to Michelson stellar interferometry, where the fringe contrast (visibility) as a function of the apertures separation is used to reconstruct the shape of a distant star., as was recently demonstrated for around-the-corner object reconstruction [31]. However, in our approach the apertures separation is fixed, and only the interference fringes positions are used to extract the TOF information.…”

A Monte Carlo framework for rendering speckle statistics in scattering media

“…ere exist several imaging techniques that directly leverage secondorder speckle statistics. Example applications include motion tracking (Jacquot and Rastogi 1979;Jakobsen et al 2012;Smith et al 2017), looking around the corner (Batarseh et al 2018;Freund 1990;Katz et al 2012), and seeing through (Bertolo i et al 2012;Katz et al 2014) or focusing through (Mosk et al 2013;Nixon et al 2013;Osnabrugge et al 2017;Vellekoop and Aegerter 2010) tissue and other sca ering layers. Most of these imaging techniques rely on the memory e ect of speckles, a fact that has motivated signi cant research on quantifying this e ect for di erent materials.…”

Multi-Modal Non-Line-of-Sight Passive Imaging

“…More details regarding the derivations of the equations can be found in Appendix B. Additional details regarding the models, including experimental verification, can be found in [16].…”

“…As described in the introduction, an increasing number of techniques have been developed for capturing coherence information. An example of practical measurements matching the requirements of our approach can be found in [16], which makes use of a Dual Phase Sagnac Interferometer (DuPSaI).…”

“…In line-of-sight (LOS) imaging, coherence preserves information such that a 3D scene can be reconstructed [19]. Recently, the retention of information was noted experimentally in NLOS sensing [16]. Here, we propose an imaging method, which demonstrates the ability to reconstruct discernible 2D projections of obscured objects in NLOS settings, by leveraging the experimentally-verified physical models of [16].…”