Light was taught to pass through opaque obstacles as if they were not there

Even scattered objects, such as clouds or sugar cubes, cast shadows because they are

disordered media that disperselight waves. But now researchers from the Vienna Technical University and Utrecht University have found a way to control light waves. They pass through objects, projecting an image on the other side as clearly as if there were no obstacle at all.

A disordered environment is, in essence,a collection of randomly located particles such as powder, sand, sugar, or even a cloud. When light hits this group of tiny obstacles, it is scattered in an incredibly complex way. But theoretically, if you could figure out this scattering pattern, you could manipulate light waves so that they pass through without scattering.

Recently, researchers managed to do just thatthis, using zinc oxide as a scattering medium, with the light source placed on one side and the detector on the other.

To begin with, the team sent through the powderspecific light signals, and then measured how they entered the detector. Using some sophisticated mathematical techniques, it is possible to determine the nature of the scattering and create a specific light wave that does not change the waveform at all. The beam of light dimmed just a little.

“As we have been able to show, there is a specialclass of light waves—so-called scattering-invariant light modes that produce exactly the same wave pattern at the detector, regardless of whether the light wave was sent only through air or had to penetrate a complex layer zinc oxide,” explains Stefan Rotter, co-author of the study.

No matter how intriguing the idea may beunhindered penetration of light through the barrier, the team of scientists went even further. By properly combining several scattering-invariant light modes, they created a light wave encoded with an image—in this case, the constellation Ursa Major—and projected it onto a detector via zinc oxide.

The new work is based on previous onesThe team's experiments on manipulating light waves to camouflage objects, such as the "invisibility cloak." The research could lead to new imaging techniques that allow people to safely see through the body, such as X-rays. However, much more work will need to be done before such technology is realized.

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