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Science/Tech See other Science/Tech Articles Title: Scientists have created the most effective “invisibility cloak” so far, and you can make one for $100 ScienceAlert... Created by scientists at the University of Rochester in New York, the device can hide large objects from sight using cheap and readily available lenses. “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,” said John Howell, a professor of physics at the University of Rochester in a press release. But while it works like an invisibility cloak, it looks more like something your optometrist would use to check your eyes - and when something is placed behind the layered lens, it disappears from view, leaving the background untouched. “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,” graduate student Joseph Choi, who helped develop the technology with Howell, said in the release. Previously, scientists had struggled to hide objects from varying angles, so they would be masked when you looked at them from straight on, but would be visible again when you moved your head. Now this new device has been used to cloak a hand, a face and a ruler from all angles. And the applications are pretty incredible - for example, a doctor could look through the lens and see the organs he was operating on below his hand. They could also let drivers see through their vehicle to their blind spot. Not to mention the fact that it can make you invisible, which is just freaking awesome. The device can also be scaled up depending on the size of the lens, and would allow large objects to be cloaked. It also works for the whole visible spectrum of light, which means there are no limitations to what it can block. It works by using four separate lenses with different focal lengths. By carefully calculating the distance between these lenses, Choi and Howell managed to bend the light around an object. They've submitted their results to the journal Optics Express, and the paper is also available on arXiv.org. The team has now released instructions and equations that will help people build a similar device at home for around $100. lens-diagram-630x290_1web 1. Purchase two sets of two lenses with different focal lengths f1 and f2 (four lenses total, two with f1 focal length, and two with f2 focal length) 2. Separate the first two lenses by the sum of their focal lengths (So f1 lens is the first lens, f2 is the second lens, and they are separated by t1= f1+ f2). 3. Do the same in Step 2 for the other two lenses. 4. Separate the two sets by t2=2 f2 (f1+ f2) / (f1— f2) apart, so that the two f2 lenses are t2 apart. They also note that achromatic lenses provide the best image quality. And fresnel lenses can be used to reduce the total length (2t1+t2). Smaller total length should reduce edge effects and increase the range of angles. Well, we know what we’re going to be trying to make at home this weekend. Check it out in action in the video below: Post Comment Private Reply Ignore Thread
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