The cloak is generated by an array of mirrors that obstruct the flow of light and creates an invisible field with almost no distortion.
A group of researchers from the University of Rochester reported to have successfully built the first invisibility cloak that operates in three dimensions. This cloak operates across the full spectral range of visible light, and prevents matter from being viewed from a range of angles. Most importantly, it generates very little distortion that would allow viewers to identify its use.
The technology is comprised of four standard lenses that work across the entire visible light spectrum, as well as a few other frequencies. The two outer lenses focus light from a wide area on two smaller lenses in the middle. The arrangement creates a region where incident light is prevented from reaching the object being cloaked, and reflected light is unable to reach the observer. This affected region of invisibility forms in the shape of a hollow cylinder.
The downside to this array is that an observer must look through the lenses in an angle of 15 degrees off center in order to not-see the visibly concealed area. With that said, it is possible to increase the size of the lenses and generate a much larger invisible area. A practical application of this technology could be found in an invisible field that would allow surgeons to see through their hands during surgery.
Physics professor and director of Rochester's Center for Coherence and Quantum Optics John Howell is the researcher of the study. Last year, Howell and his son created a wearable invisibility cloak that worked using mirrors for $150.