Two physicists at the University of Rochester recently unveiled a new device that can cloak objects using nothing but properly arranged glass lenses.

Professor John Howell and optics graduate student Joseph Choi concealed objects with innovative insights, not with any advanced technologies or expensive equipment. Their device, which consists of a system of four lenses, is essentially air, through which the lenses bend light.

Howell discovered that as the light converged and diverged from lens to lens, objects could be hidden within the system but outside the light’s path.

“The light will not interact with your hand or something between the lenses. (The system of lenses) creates a region that it is inaccessible to your eye,” Howell said.

The human eye can only see objects that come into contact with light. That means if an object is placed in between the lenses where light will bend around it, the object will appear to be concealed when looking through the lenses.

It costs a few hundred dollars to make the device which functions for many lines of sight, meaning that the effect will hold even if you look through the lens at different angles. The device also works for the entire visible spectrum, which means it works for all the colors that the human eye can see, Howell said.

Not to mention, anybody can set up this device with a little bit of math. David Barnstone, the University of Rochester’s press officer for engineering and science, said that’s probably why news about the device spread so quickly.

“This is something that you can create yourself,” he said. “With a couple hundred dollars you can set it up like they did. You can make this at home.”

With cheaper lenses, people could do it at home for even under $100, said Choi, the graduate student.

The experiment started with computer simulations by Choi after Howell shared his idea with him. At first, Choi wasn’t even sure the idea would work, he said. After Choi’s simulations showed that Howell’s idea was possible, Howell built a successful prototype using mirrors. He and Choi then optimized the design to use only four lenses.

Using relatively simple and well-known optics equations that most college level math students can solve, Choi calculated the distances between the lenses that would cause light to bend as it traveled through the lenses.

“It’s linear algebra and then just algebra. That’s all you need,” he said. “But if you just want to build a four lens, we already solved (the equations) so all you need is a calculator.”

The device also accounted for any fuzziness in the background. If the distances or sizes of the lenses were wrong, the background image could be unclear or an object might not be concealed. Howell and Choi’s design managed to account for both. They have a provisional patent application on their device so it is protected as it goes through the patent process.

Though Howell and Choi finished the work in April, they wanted to wait until they had filed for a patent before they started to discuss the research. Their paper is currently undergoing peer review for possible publication in Optics Express.

Choi said he looks forward to continuing his optics research and was glad people took an interest in it.

“I am happy that people took an interest in this and the media took an interest in this,” he said. “It was very surprising and pleasant to know that the media and a lot of people in the general public actually do find these things interesting.”

Published on October 9, 2014 at 12:01 am

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