Researchers create special light waves that penetrate opaque materials

Researchers from Utrecht University and TU Wien (Vienna) have created special light waves that can penetrate opaque materials as if the material wasn't there. The beam of light can pass through a distorted medium and project the same picture onto a detector that would be detected without the medium in the way.The researchers say that for any specific disordered medium, be the medium sugar cube or something else, tailor-made light beams can be constructed that are virtually unchanged by the medium. However, the light beams are attenuated. The beams of light can penetrate the medium, and a light pattern arrives on the other side with the same shape as if the medium wasn't there at all.

Researchers believe that the idea of "scattering-invariant modes of light" could be used to examine the interior of objects. Professor Stefan Rotter and his team developed mathematical solutions to describe these light scattering effects. In their research, the team used a zinc oxide layer, which is opaque, as a light-scattering medium. It's made up of a white powder of completely randomly arranged nanoparticles.

The team shined precise light signals through the zinc oxide powder and measured how light arrived at the detector behind it. Researchers were able to conclude from that experiment how any other wave is changed by the medium. It's possible to calculate specifically which wave pattern is changed by the zinc oxide layer exactly as if wave scattering was absent in the layer.

Researchers on the team were able to show that a very special class of light waves, known as scattering-invariant light modes, would produce the same wave pattern at the detector regardless of whether the light waves were only sent through the air or if it had to penetrate the complex zinc oxide layer. The experiment showed that zinc oxide doesn't change the shape of the light waves; they simply get a little weaker overall. The discovery of light patterns able to penetrate objects largely undisturbed could be used in medical imaging procedures in the future.