The 'magic' brush of objects becomes invisible

Researchers from Purdue University (USA) have designed a device that looks like a brush, allowing one day to make large objects like planes disappear under light.

Previously, many other researchers tried to cloak objects in the microwave light (shortwave) - that is, the wavelength is much larger than the visible light. However, this is the first design that can "disappear" objects of all sizes, within the visible light of the human eye.

This " invisibility mask " actually consists of many tiny metal needles, attached to a brush-shaped hat, at the corners and lengths so that the light shining on it goes around the mask. This makes every object behind the hat seem to disappear, because light does not reflect from it.

Refractive index

Small needles are attached to a brush-like device, in a device that can theoretically be invisible.(Photo: Stockphoto)

Want to disappear something, people just adjust the needle to change the refractive index around the cone.

Each material has its own refractive index, which determines the degree of bending and slowing light when it passes from one material to another. (This effect is visible when dropping a chopstick into a glass of water, viewed from outside the wand as bent in the water exposed to the air).

Normally, natural materials have a greater refractive index than 1. But the tiny needle layer inside the cone will gradually change this index from 0 (on the inside of the mask) to 1 on the outer surface. same of the mask. This causes light to be bent around the object to be invisible.

The needles, according to hypothetical designs, are about 10 nanometers wide (1 nanometer is 1 billionth of a meter) and are hundreds of nanometers long.

"It sounds fictional, but in fact it completely obeys the laws of physics," said lead researcher Vladimir Shalaev, an electrical and computer engineer at Purdue. "Ideally, if we make a real thing, it will work like Harry Potter's invisibility mask, and it's not heavy because it contains very little metal in it , " he said.

Shaleav said he needed to raise funds to build the device and hoped it would come out in 2-3 years.

The biggest drawback of today's design is that it can only bend light at a single wavelength, not with the entire visible light band.

However, even when limited to one wavelength, it will still bring many useful applications, such as covering soldiers from night-vision goggles, or hiding objects in front of devices. Special target military detection.

T. An