Brett Smith for redOrbit.com – @ParkstBrett
From Harry Potter to the Invisible Woman, popular culture has often romanticized the idea of making people invisible. Now, a new study from Russian and Austrian engineers has taken us one step closer to that possibility.
Published in the journal Scientific Reports, the new study described how the team was able to make homogenous cylindrical objects invisible in the microwave range of the light spectrum.
The new research is based on studies of light scattering from a glass cylinder filled with water. These studies show the unusual physical properties of materials with “high values of refractive index”. In the new study, the scientists were able to adjust the refractive index of water by regulating its temperature.
When light hits the cylinder, it is scattered by two mechanisms: resonant and non-resonant scattering. The study team found that at particular frequencies, light scattered the two mechanisms have opposite phases and cancel each other out, making the object invisible.
Applied to electromagnetic wave ranges
Based on this knowledge, the study team was able to achieve the first experimental observation of a homogeneous object becoming invisible by scattering cancellation. The team was able to switch between visible and invisible at the same frequency of 1.9 GHz by altering the temperature of water in the cylinder, from 194 to 122 degrees F.
“Our theoretical calculations were successfully tested in microwave experiments,” said study author Mikhail Rybin, a metamaterials researcher at ITMO University in Saint Petersburg, Russia. “What matters is that the invisibility idea we implemented in our work can be applied to other electromagnetic wave ranges, including to the visible range. Materials with corresponding refractive index are either long known or can be developed at will.”
The study team work’s is different from another kind of prominent invisibility research involving metamaterials, which are artificial structures with specific optical properties. Metamaterials can change the direction of light by making it curve around a cloaked object. Coating objects with metamaterials is difficult because they are difficult to fabricate and are not compatible with conventional applications.
The method utilized in the new study is based on a new understanding of scattering processes and surpasses the metamaterials approach in terms of simplicity and cost-effectiveness.
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