This article was posted on 03/07/2013

How holograms could help firefighters better locate victims amid fire, smoke

Advancement of infrared technology could make locating downed victims a more efficient process

One of the greatest challenges a firefighter faces is being able to see through fire and smoke in order to get to people in need of rescue.

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At present, firefighters can see through smoke using IR camera technology. The problem with this particular technology, however, is that it can be blinded by the intense infrared radiation emitted by flames, which overwhelm the technology’s sensitive detectors.

A group of Italian researchers looking to improve upon this technology have proposed a new imaging technique that uses infrared digital holography instead.

Comparing IR-camera technology with IR-digital holography
While IR-camera technology can see through smoke, it can be blinded by flames (top). IR-digital holography, on the other hand, does a better job at avoiding these blind spots (bottom).

Their work was published in the latest publication of Optical Society’s journal, Optical Express.

The benefits of infrared digital holography

The group proposes that their lens-free technique is able to better cope with the flood of radiation when in an environment filled with smoke and flame.

“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,” explains 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.


Man viewed through flames use holographic imaging 


How holography works

Holography refers to the producing of a 3D image of an object. In order to create a holograph, a laser beam is split into two — an object beam and a reference beam. The former is shone on an object to be imaged. When the reference beam is also shone on this object, an interference pattern is created to encode the 3D image of that object.

But that’s just holography in general. What the researchers did was create a lens-free beam of infrared laser light that gets widely dispersed throughout a room. Since the beam does not employ a lens, light is able to be distributed over the whole array of camera pixels. This helps it avoid oversaturation / blind spots produced by flames.

The infrared laser beams pass through smoke and fire unhindered and when they reflect off the objects and people in the room, the information is recorded by a holographic imager and decoded to reveal everything in the room.

What’s more, objects need not be stationery, as the technology can capture objects in motion.

Below is a video that the team put together to show the new holographic technology:



While it might sound like this new technology is ready for immediate implementation, the next step is to get it into a portable, tripod-based system that can house both the laser source and infrared camera.

Looking a bit further down the road, the group is also considering a way to get the technology into buildings and tunnels.

Outside of firefighting, the team is considering the technology for use in the biomedical field for non-destructive testing of large aerospace composite structures.


The team's paper, “Imaging live humans through smoke and flames using far-infrared digital holography” is available for free download at

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