A group of Canadian researchers led by Professor Jose Azaña this week published an academic paper describing the process of creating an invisibility device invented by them. The apparatus is able to prevent the reflection of the light and, with this, to hide another object of any color of the visible spectrum.
The technique used is different from that used in the scientific environment to seek the creation of a truly functional device for invisibility. Until then, the technique consisted in illuminating a colored object with a light of opposite color within the visible spectrum. In laboratories with controlled environments, it was then possible to disguise the objects, but they were not completely imperceptible to the human eye. Otherwise, in trying to reproduce these experiences in the natural light of the Sun, the results were always negative.
In summary, conventional solutions were based on altering the propagation of light around the object to be hidden, but due to the frequency difference in the waves of each color, a problem arose. “The problem is that the different colors or frequencies of the spectrum of light require different intervals of time to pass through the invisibility device. As a result, the time distortion created around the device reveals its presence, ruining the invisibility effect, “Professor Azaña told El Pais.
The solution found by the Canadian team is based on the “Talbot Effect” and causes light waves to propagate through the object without being reflected, instead of forcing them to get around something. To this end, scientists have studied the propagation of light waves of each visible and non-visible color. With this knowledge, they were able to first shift the light frequencies to other regions of the spectrum that would not be affected by the reflection or propagation caused by the object being hidden.
The concept seems complex 😕 , but the idea itself is not that complicated. An example of how this technique works would be: a green object is perceived by the human eye because it is able to reflect only the green light of the visible spectrum, so the researchers use the device to move the green light to another part of the spectrum blue, for example) before it reaches the object. In this way, when natural light reaches the element to be hidden, it can not be reflected and “passes by” .
For now, this effect can only be reproduced in one dimension. In this way, if a person looks at the object camouflaged from a different angle, it will be able to perceive the disturbance of light.
As the Talbot effect can be observed in all wave types, the Azaña team’s research can be applied in other fields. “The processes used in our study are of a universal character and therefore could be applied to waves of a nature other than electromagnetic,” the researcher explained. According to them, the same process created to make objects “immune” to light could be modified to create new methods of thermal and acoustic insulation or even to make buildings earthquake proof, since it might be possible to avoid the reflection of thermal and mechanical waves in these buildings.
Researchers are now moving on to the second phase of the project, which seeks to hide objects in multiple dimensions, but there is not yet a prediction for a Harry Potter-style “invisibility cloak” to hit the market.