Virtual Simulation of Cloaked Objects Created

With the inevitable advent of metamaterials and invisibility cloaks, the world is eager to know precisely how a hidden object would look like in real life. While practical applications are still some time away, German researchers at the Karlsruhe Institute of Technology have recently released a series of pictures on the issue, detailing how a computer model sees an object hidden by an invisibility cloak. Details of the process they used appear in the latest issue of Optics Express, the open-access journal of the Optical Society of America (OSA).

“It's important to visualize how an optical device works,” says Jad C. Halimeh. He is the scientist who wrote and tested the new simulation software, as part of his Master's thesis at KIT. The images presented in the journal entry, entitled “Photorealistic images of carpet cloaks,” show a museum nave. The floor has a large bump in it, but an invisibility cloak, known as a carpet cloak, is seated on top of it. The scientists draw attention that the “ostrich effect” is very pronounced in their images. That is to say, even though the effect of the bump is concealed, the cloak itself is visible, due to imperfections and surface reflections.

The model, Halimeh adds, is especially designed to handle the complex mechanisms involved in metamaterial optical cloaks. This new class of materials, that was only discovered a few years ago, is incredibly hard to produce, but it's able to bend, handle, and direct light unlike anything else on the planet. Inside an invisibility cloak, for example, these materials are the main element, forcing photons in light around the object that needs to be concealed, and then setting them back on their trajectory, without any apparent changes.

Up until now, the invisibility cloaks produced in the lab work on only narrow wavelengths of light. The proof-of-concept was created at the Duke University in 2006, when researchers there managed to make an object invisible to a portion of the microwave spectrum, using metamaterials. Since then, advancements have been made, but no cloak able to conceal an object in the entire broad wavelength spectrum the human eye can see has ever been produced. The new software, which will soon become commercially available, will offer a boost in that direction, its creator believes.