Photo: Duke University Photography
Hiding an object from view isn’t just a trick for science fiction storytellers — researchers are getting closer to being able to hide a solid object from sight, new research suggests.Study researcher David Smith, from Duke University, and his graduate student, Nathan Landy, have created a structure that can guide electromagnetic waves around an object and have them converge on the other side.
To an outside observer, these waves look like they passed right through the object. Their work was published online yesterday, Nov. 11, in the journal Nature Materials.
“We built the cloak, and it worked,” Landy said in a press release from the university. “It split light into two waves which traveled around an object in the centre and re-emerged as the single wave.”
The “light” he mentions is actually microwaves — the same kind that cook your food — not visible light. The light that we see with our eyes is just electromagnetic energy that travels at the right frequencies, or wavelengths, for our eyes to detect.
Other types of electromagnetic energy, including x-rays, ultra violet light, infrared light, microwaves, and radio waves, none of which we can see. Microwaves, which were used in this study, are at a lower energy frequency than visible light, which makes them easier to deflect around an object.
The team’s latest cloak is similar to a previous one they made in 2006 out of parallel and intersecting strips of fibreglass etched with copper. While that cloak bent electromagnetic waves around an object, making it invisible, a dark shadow was visible behind it because of waves reflecting off the cloak.
Their latest iteration is diamond shaped and adds copper strips to perfect the invisibility. By minimising the reflection there was no shadow and a one centimeter tall cylinder object became perfectly invisible in the microwave spectrum.
Perfecting cloaking in lower energy wavelengths, could lead to visible-light cloaking devices, but those may still take a while. But before then the ability to control light and other electromagnetic waves, a new field of science called transformational optics, could lead to faster electronics and internet.
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