Scientists have developed an “invisibility cloak” that makes objects invisible to the naked eye.
The cloak, which is actually a lump of crystal, can only hide small objects such as paperclips and pins at the moment but it is the first of its kind to work in the perceivable spectrum of light. The groundbreaking research paves the way for more sophisticated devices in the future.
The cloaking device is made from two calcite prisms joined together to make a pyramid, with the underside of the pyramid coated in gold to make it reflective. The researchers found that calcite, a transparent crystal, has natural light-bending properties which help the device to hide objects. Light rays passing through the pyramid are bent, making the base of the pyramid look flat. “The cloaked region is the space at the bottom of the calcite prism,” Shuang Zhang, the lead researcher at the University of Birmingham said. “Anything you put there won’t be seen from outside.”
The device is not perfect, but it does pave the way for further breakthroughs. At present, the cloak itself is transparent though it is visible – it only hides small objects inside the prism. Under water, however, the cloak is almost completely invisible. Zhang said it may be possible to coat the cloak to make it less visible. It also must be placed on a surface to work.
Possible applications for use inevitably lie in military use, unfortunately. Future developments could be used to hide military hardware from view, although Zhang believes that it could be used for cosmetic purposes, too. “If you had a mole on your face, you could potentially cloak it so it won’t be seen,” Zhang said. “Though you do need a fairly large cloak to hide even a small thing.”
Still, it will be interesting to see what the future holds for cloaking devices. Perhaps Harry Potter’s invisibility cloak is not so far fetched after all…
- Do you want an invisibility cloak like Harry Potter’s? Here it is (guardian.co.uk)
- Invisibility cloaks get bigger and better (blogs.nature.com)
- Crystal-clear idea for cloaking (bbc.co.uk)