Towards Zero-power 3D Imaging: VLC-assisted Passive ToF Sensing

Passive Time-of-Flight (ToF) imaging can be enabled by optical wireless communication (OWC). The lighting infrastructure is the backbone of emerging light-based wireless communication. To this end, communication sources are used as opportunity illuminators to probe the scene, and an array of time-resolved pixels are exploited to demodulate the return, provided that the ToF camera can be externally synchronized. Our work employs a direct line-of-sight path to synchronize the camera externally. Together with the indirect path given by the reflections from the scene, this yields a bistatic configuration. Each Time-of-Flight (ToF) measurement induced a solution space of ellipsoidal shape and redefined the image formation model based on the bistatic configuration. In this demo, we showcase a passive ToF camera capable of delivering intensity and depth information in practice without emitting photons from the ToF camera. Our passive modality can eliminate built-in illumination sources, thus coping with optical power constraints, as is desired in future ToF cameras.