Holograms help firefighters see people trapped in flames

Current infrared cameras can be blinded by the intense radiation emitted by flames. A new digital holography system can produce a live 3-D movie of people in a room on fire.
Written by Janet Fang, Contributor on

Researchers in Italy are using an infrared digital holography system to help firefighters look for people trapped in flames.

This lens-free, fire search and rescue system -- developed by Pietro Ferraro and colleagues from the National Institute of Optics in Pozzuoli -- produces a live holographic movie that reconstructs motion hidden by a fire.

Firefighters can see through smoke using infrared camera technology. But IR cameras can’t capture people blocked by flames because they rely on a lens to produce an image. A zoom lens concentrates rays on the sensor, and the intense infrared radiation emitted by flames overwhelm and blind the sensitive detectors.

A lens-free setup, on the other hand, can cope with the flood of radiation since it isn’t focused on any one area. And with holograms (like the ones on credit cards), partial data contains information about the whole structure -- so you can use a very small subset of pixels to reconstruct a whole object.

To create a hologram, a laser beam is split into two: an object beam and a reference beam. You shine the object beam onto the thing being imaged; when the reflected object beam and the reference beam are recombined, they create an interference pattern that encodes the 3-D image.

In the new system, a beam of IR laser light is dispersed throughout a room, passing through flames and smoke. The light reflects off of any objects or people in the room, and the information carried by this reflected light is recorded by a holographic imager.

It’s then decoded to produce an almost real time, 3-D movie of the room and its contents. You can watch a video of the thermographic view vs. holographic view.

The team plans to make a portable tripod system that holds the laser and the holographic camera, allowing the system to be fixed inside buildings or tunnels.

The system could also have biomedical applications: “studying or monitoring breathing, cardiac beat detection and analysis, or measurement of body deformation due to various stresses during exercise,” Ferraro says in a press release.

The work was published in Optics Express last week.

[Via New Scientist, Wired]

Images: Optics Express

This post was originally published on Smartplanet.com

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