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Wi-Fi signals could be used to make holograms

Joseph Flaig

Researchers used a standard Wi-Fi signal to create a 3D image of an object (Credit: iStock/ alxpin)
Researchers used a standard Wi-Fi signal to create a 3D image of an object (Credit: iStock/ alxpin)

Hello, holograms. Researchers have used Wi-Fi signals to look through walls and create highly-detailed 3D images of people and objects within.

Physicists at the Technical University of Munich hope further advancement of their new method may aid in the recovery of victims under avalanches or collapsed buildings. Holographic wireless signal processing could create virtual models of destroyed structures, allowing first responders to navigate around heavy objects and use cavities in the rubble, finding the easiest approach to quickly reach victims.

Friedemann Reinhard and Philipp M. Holl created images of an object within a room by analysing wireless signals from a standard router. Using holographic data processing, they converted the radiation bouncing around a room into a 3D image. The images revealed a “metallic cross-shaped phantom object” – a metal crucifix placed in the room.

A metal cross was placed in the room with the router and was seen after the radiation was analysed (Credit: Friedemann Reinhard/ Philipp Holl/ TUM)

metal cross was placed in the room with the router and was seen after the radiation was analysed (bottom right) (Credit: Friedemann Reinhard/ Philipp Holl/ TUM)

With future developments such as higher bandwidth standards, the researchers say the method could be adapted to create moving images with resolutions down to the millimetre range. The technique could also work with Bluetooth and mobile signals and would not be halted by encryption.

“Of course, this raises privacy questions. After all, to a certain degree even encrypted signals transmit an image of their surroundings to the outside world,” said Reinhard, the project leader. However, he added that it was unlikely that the process would be used to look into “foreign bedrooms” in the near future due to the impracticalities of carrying large antennae around buildings.

The report instead claims the method could be attractive for a variety of applications, including localisation of radio-frequency tags in Internet of Things networks and 3D motion capture for video games.

The research is published in Physical Review Letters.

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