Seeing through smoke and flames: a challenge for imaging capabilities, met thanks to digital holography at far infrared

We show that imaging alive people through smoke and flames is possible by Digital Holography at far infrared. This capability is of crucial importance in the security field to provide a new tool for firefighters and first responders in fire accidents. So far, the existing thermographic infrared cameras allows to see people through dense smoke, sensing the radiation emitted by human body. However, these devices are often blinded due to the flame emission, which is collected by the zoom lenses employed for the scope, and the information of the targets beyond the flames is unavoidably lost. On the contrary, lensless Digital Holography at far infrared avoids the typical saturation of the camera detectors returning clear images of targets seen behind veils of smoke and curtains of flames. Moreover, we demonstrate that human-size holograms can be recorded, allowing to move this promising technology outside the lab for safety applications.