Most of us have wished we could be a fly on the wall during a specifically juicy conversation, or disappear into the background after an embarrassing mistake. Not surprisingly, invisibility cloaks are mainstay for a fantasy fiction.
In recent years, there were many attempts to make some kind of invisibility tech. Now, UK-based start-up Invisibility Shield Co. has come forward with a new product that will help you to satisfy that dream of turning into invisible… kind of.
As you could see in the pictures here, a person standing at the back of the shield actually does seem to disappear. This happens because of a simply fun optical phenomenon referred to as lenticular lensing, where a series of thin, cylinder-shaped lenses are organized parallel on a surface.
There is just common use for lenticular lensing you have probably encountered: in tilt cards that change the image depending on angle.
Of course, the use of lenticular lensing could be a little extra complex while we are talking about a whole invisibility shield, instead that only a postcard, however the basic principles are the same.
“Each shield uses a precision-engineered lens array to direct lots of light reflected from the object away from the viewer and send it sideways around the face of the shield to the left and right,” writes the start-up on their Kickstarter for the product.
“Because the lenses in this array are aligned vertically, the vertically aligned strip of light reflected from the standing or crouching subject quickly becomes very diffuse when spreads horizontally on passes through the back of the shield.”
The lenses in that case are too similar to the rows of horizontal bumps on these tilt cards, however, rather of light entering and exiting the card at different angles from the front, the light comes from behind the shield.
When it enters the array, the light hitting the sides is stretched to cover the whole surface, blurring the image behind it. Meanwhile, the most central light behind the shield, where the “disappeared” object is located, is reflected back and out. the sides.
The shield is mainly appropriate at maintaining the integrity of horizontal lines, however due to the fact the lenses on the shield are vertical, it is much less powerful at showing vertical lines behind a person – rather developing a sort of smudge of background light. You can be able to see this in the image below, wherein tiles disappear as much as the person, while the darkish edge of the step seems intact.
“You can think of it like a waveguide, directing rays around the object,” Alex Dinovitser, a metamaterial physicist at the University of Adelaide said. In physics, waveguides can be viewed as structures which direct electromagnetic waves in a specific direction. They’re used in electronics (your microwave has a waveguide, for instance), but there are also optical waveguides.
The principles aim of the product Invisibility Shield Co. is pitching on its Kickstarter have been really around for some years. A 2019 showcase video by the military stealth company, Hyperstealth, suddenly inspired crafty folk on YouTube to attempt to replicate what they saw, with great success.
There’s also a freely-available instruction manual by engineer and YouTuber Ian Charnas on how to craft your own.
Of course, this technology wasn’t invented to only prank your friends. Hyperstealth have been marketed as an obscuring device for aircraft or tanks. This is supported by the fact that lenticular lensing like this work best the far away you are from the lens. But, simply cloaking something visually is not particularly useful for military purposes. Different obscuring devices are required depending on what you are tracking.
“There are many different technologies. For example, this technology isn’t the same as for making a plane invisible to radar,” Dinovitser said.
“In that case, the surface is created to entirely absorb the radiation or light. For light, the best material for this kind is VantaBlack. It’s not the same as an invisibility cloak where light goes through & around.
After all, this shield is just a consumer-oriented product, while “invisibility research” has been done for the past few decades, leading in things like an invisibility cloak to sound, electromagnetic waves, and also for visible light (in one colour only).