By REGINA PALATINI Senior Staff Writer
The cloaking devices made famous in Star Trek and Harry Potter have been slowly making their way from science fiction to fact.
Recently, scientists at the University of California, Berkeley and the U.S. Department of Energy’s Lawrence Berkeley National Laboratory have succeeded in creating a cloak that can effectively make an object invisible.
In the study, researchers created a “skin cloak” that follows the surface of an object and prevents it from being detected under visible light. The skin cloak is approximately 80 nanometers thick and changes the direction of the reflected light waves, rendering the object invisible to optical detection. Presently, the cloaking effect only works on microscopic objects. “This is the first time that a 3-D object of arbitrary shape has been cloaked from visible light,” Xiang Zhang, director of Berkeley Lab’s Material Sciences Division, said in a press release.
The effect depends on metamaterials, which use engineered substances to produce properties that don’t occur in nature. Zhang and his group have been working for the past 10 years on using metamaterials to alter the way in which light travels, curving it or bending it backward and rendering the “cloaked” device invisible.
“Creating a carpet cloak that works in air was so difficult we had to embed it in a dielectric prism that introduced an additional phase in the reflected light,” Xingie Ni, one of the lead authors a member of Zhang’s research group, said in the press release.
When we see an object, our eyes capture the light that is scattered off of the surface, and our brains process the light so that we perceive an image. If the light from an object can be manipulated before it reaches our eyes, then the process can be halted to prevent us from ever seeing an image.
Manipulating how light and metamaterials interact offers promising applications to high-resolution microscopy and ultra-fast computers. Benefits of the technology could include security encryption and masking microelectronic components.
The military is particularly interested in large-scale cloaking devices for approaching and monitoring a site without detection.The promise of invisibility is an attractive field, and researchers at other institutions are working on similar projects to manipulate both light and sound waves.
Scientists at MIT have applied cloaking technology to electronics. By allowing particles to “hide” from passing electrons, this form of cloaking may lead to more efficient thermoelectric devices and new kinds of electronics. Duke University scientists used 3-D metamaterials to reduce the speed of sound waves and change how the waves bounce off of an object, silencing the sound.
In addition to using metamaterials, scientists at the University of Rochester have developed a lens array system that bends light in a manner that makes anything in its path invisible to the observer. The system can be set up using commercially available lenses for about 100 dollars.
Due to the fact that this system relies on lenses, it’s better suited for seeing around objects, rather than rendering something invisible.
With this technology close to becoming a reality, we may need to take a closer look at what we see, or ask what we may not be seeing.
