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UP scientists invent invisibility cloak for classroom use

Now even Philippine high schoolers can experiment with making things invisible.

Scientists from the University of the Philippines’ National Institute of Physics (NIP) recently built on the work of US scientists to create an affordable “invisibility cloak” which, though it might not be at Harry-Potter levels just yet, is cheap enough for even high school students to experiment with making things disappear.

Researchers Miguel Revilla, JC Lorenzo, and Nathaniel Hermosa found a way to make an invisibility cloak out of readily available off-the-shelf parts, including optics salvaged from old office equipment.

“Our first experiments on cloaking with different focal lengths were with lenses which came from old overhead projectors and telescopes,” Hermosa said in an interview.

In a demonstration of this new setup, the researchers showed that a metal bar inserted in the middle of the apparatus disappeared completely from view as if it didn’t exist, allowing the NIP logo in the background to be clearly seen:

The ability to disappear at will has been the stuff of science fiction and fantasy for ages. From Plato’s Ring of Gyges to Rowling’s Cloak of Invisibility, people have always wanted to make such a “cloaking device” an everyday reality.

Long before the technology that enabled the creation of an invisibility cloak came around, it was already clear what needed to be done to achieve the effect. 

We’re able to see things because light generally travels in a straight line until it is either blocked or reflected by an object. But what if it were possible to bend light around an object so that it reaches our eyes as if there’s nothing in the way?

The simplest way to make something invisible is to use mirrors, but this isn’t true invisibility because looking at the setup from even just a slightly different angle would break the illusion. What you really need is a set of lenses surrounding the object in such a way that keeps the object invisible from a variety of angles and positions.

To date, the most popular such setup is the “Rochester Cloak,” developed in 2014 by then doctoral student Joseph Choi and professor John Howell at the University of Rochester in New York, USA.

The problem with the Rochester Cloak, however, is that there are limits to the kinds of lenses that can be used, as well as the size of the setup.

But the Filipino physicists were able to simplify the Rochester Cloak by making it more compact as well as by finding out how different lens combinations—with various focal lengths, instead of just two pairs of lenses with the same focal lengths, as in the original setup—could be used to achieve the cloaking effect. They thus developed an invisibility cloak that's much easier and cheaper to put together, making it ideal for classroom optics experiments.

“Schools lacking sets of lenses can benefit from this as well. They may have old or broken overhead projectors where they can get the lenses from,” Revilla said.

But we’re still a long way to go from a true invisibility cloak, according to the researchers. A real cloak would have to be able to work with a wide range of light and be able to make large objects disappear even when viewed from anywhere. Revilla points to developments in materials science that may hold the key to making something not out of lenses but out of a special light-bending material.

“Research in invisibility is continuous and new technologies and materials are being developed and fabricated yearly,” Revilla explained. “Probably the difficult part of making the cloak is developing the material itself.”

Still, Hermosa believes that their current work could have a big impact on kids who are curious about science and who may, hopefully, be inspired to pursue scientific careers. High school teachers could use the setup to challenge students to come up with a working cloak given a set of cheap lenses. Or college undergraduates could use it to better understand its underlying equations and concepts.

“I want something that will benefit physics education. My gut feel is our research will have a much heavier impact in the education community,” Hermosa concluded. — DVM, GMA News