How did they do it? A team of researchers from the University of Utrecht and TU Wien (Vienna) has created special light waves with the ability to penetrate objects – even opaque ones – and make them practically invisible to our eyes.
As if they weren’t there
Do you know why a sugar cube is not transparent, for example? Because the light that enters it is scattered, altered and deflected in a very complicated way. However, these researchers have shown that there is a very special class of light waves for which this does not apply: it is possible to build custom-made light beams that are practically not modified by this medium, but only attenuated. The beam of light penetrates the object and a pattern of light reaches the other side that is the same shape as if the object was not even there.
Does it still sound like science fiction to you? These are the so-called “scattering invariant light modes” . We have already seen that light cannot normally penetrate certain materials, or only to a limited extent, because the light is scattered, altered and deflected, but thanks to these light waves opaque objects become transparent, which means that beams of light could be created for any object as they would result in this creation of ‘invisible’ solid objects.
Creating ‘invisible’ solid objects
Just as ripples on the water’s surface could take an endless number of different shapes, light waves could also have an infinite number of different shapes, scientists say. “Each of these light wave patterns changes and is deflected in a very specific way when sent through a disordered medium,” explains Professor Stefan Rotter from the Institute for Theoretical Physics at the Vienna University of Technology, who is working on with his team on mathematical methods to describe such light scattering effects.
“As a means of scattering the light, we use a layer of zinc oxide, an opaque white powder of nanoparticles arranged completely randomly,” explains Allard Mosk, director of the experimental research group. “In the experiment, we see that zinc oxide doesn’t actually change the shape of these light waves at all, they just weaken a bit overall, ” continues the expert.
Applications
What could these special light waves be used for ? This method of finding patterns of light that penetrate an object could also be used for imaging procedures.
“In hospitals, X-rays are used to look inside the body; they have a shorter wavelength and therefore can penetrate our skin. But the way a wave of light penetrates an object depends not only on of the wavelength, but also of the waveform “, clarifies Matthias Kühmayer. “If you want to focus light within an object at certain points, then our method opens up completely new possibilities. We were able to show that using our approach, the distribution of light within the zinc oxide layer can also be specifically controlled .” This could be interesting for biological experiments, for example, where you want to introduce light at very specific points to look inside cells.
Light instead of X-rays? It is a possibility that could revolutionize certain procedures in the future. There is a long way to go, but the horizon looks very interesting.
Referencia: Scattering invariant modes of light in complex media. Pritam Pai et al. Nature Photonics (2021). DOI:https://doi.org/10.1038/s41566-021-00789-9
