A team of Italian researchers has developed a new imaging technique that uses infrared (IR) digital holography to allow firefighters to see through smoke and flames.
Firefighters can see through smoke using current IR camera technology. However, such instruments are blinded by the intense infrared radiation emitted by flames, which overwhelm the sensitive detectors and limit their use in the field. By employing a specialised lens-free technique, the researchers have created a system that is able to cope with the flood of radiation from an environment filled with flames as well as smoke.
'IR cameras cannot see objects or humans behind flames because of the need for a zoom lens that concentrates the rays on the sensor to form the image,' says Pietro Ferraro of the Consiglio Nazionale delle Ricerche (CNR) Istituto Nazionale di Ottica in Italy. By eliminating the need for the zoom lens, the new technique avoids this drawback.
He continued: 'It became clear to us that we had in our hands a technology that could be exploited by emergency responders and firefighters at a fire scene to see through smoke without being blinded by flames, a limitation of existing technology,' Ferraro says. 'Perhaps most importantly, we demonstrated for the first time that a holographic recording of a live person can be achieved even while the body is moving.'
In the researchers’ new imaging system, a beam of infrared laser light is widely dispersed throughout a room. Unlike visible light, which cannot penetrate thick smoke and flames, the IR rays pass through largely unhindered. The IR light does, however, reflect off of any objects or people in the room, and the information carried by this reflected light is recorded by a holographic imager. It is then decoded to reveal the objects beyond the smoke and flames. The result is a live, '3-D movie' of the room and its contents.
The team has described its breakthrough results and their applications in the Optical Society’s (OSA) open-access journal Optics Express.