3D Continuously Multidirectional Cloaking Device Uses Low-Cost, Ordinary Lenses
Scientists have recently developed several approaches to 'invisibility cloaks' which hide objects from view. A new method from the University of Rochester uses inexpensive, readily available materials in a novel configuration. "There've been many high tech approaches to cloaking and the basic idea behind these is to take light and have it pass around something as if it isn't there, often using high-tech or exotic materials," says John Howell, a physics professor at the University of Rochester. Howell and graduate student Joseph Choi developed a combination of four standard lenses that keeps the object hidden as the viewer moves up to several degrees away from the optimal viewing position. "This is the first device that we know of that can do three-dimensional, continuously multidirectional cloaking, which works for transmitting rays in the visible spectrum," said Choi. The new cloak can be scaled up as large as the size of the lenses, allowing fairly large objects to be cloaked. And, unlike some other devices, it's broadband so it works for the whole visible spectrum of light, rather than only for specific frequencies.
Transcript
00:00:07 [John Howell] So, cloaking is essentially just an optical illusion and people have been doing that for hundreds of years. There have been many high-tech approaches to try and achieve cloaking and the basic idea behind these high-tech or exotic materials is to take light and have it pass around something as if it isn't there and so we just figured a very simple way of doing that can just be using standard lenses and things that we would normally find in the lab. [Joseph Choi] What we've tried to develop is a simplified version are a perfect cloaking device for small angles and what we've done is we've simplified it to a four-lens system. And as you can see all we've used are
00:00:49 off-the-shelf optics that we can get from any of the optical stores and the great thing about this is, it can be scalable to any size that you can make the lenses but the most important thing that we've done so far is this is the first device that we know of that can do three-dimensional continuous multi-directional cloaking. So if you have rays that go at different angles you can have the cloaking device still cloak it while what you see in the background is shifted accordingly without any distortion or changes.
00:01:23 Say we place an object in our case a ruler in the middle if we don't have the lenses, we would be able to see the ruler, but what the lenses do is the lenses actually cloak the ruler so if you were standing right here and you look straight through what would happen is the rays would focus and then diverge out so it actually bends the light around the ruler so that you won't be able to see the ruler if you looked at it straight down. So, we have slightly more complicated designs where an object can be cloaked entirely, but we've tried to simplify our design and what we have is where the light goes
00:01:59 through this center of the design so that cannot be blocked. So the cloakng region is actually a ring-shaped area on the outside rather than in the center. [John Howell] People have been fascinated with cloaking for a very long time and it's recently been a really popular thing for example in science fiction and also in Harry Potter but I think people are really excited by the prospect of just being invisible [Joseph Choi] For scientists it's also very fascinating because we can actually put math and science behind that to make that a reality. E ven though that's been a difficult subject to implement it's very fascinating scientifically too.