Invisible Cloaks, Translucent Walls

jd writes "The University of Tokyo has developed the illusion of invisibility, under the name of 'Optical Camouflage.' The system is remarkably simple - you have a mix of light-sensitive and light-emitting devices attached to an adapted reflective surface. The devices are hooked to a computer, which simply projects on each side whatever is on the opposite side. The result is more of a translucent look, than real invisibility, but the potential is there. The inventer's next objective is to make walls that are invisible, using the same technology. Project a real outside image onto an interior wall without windows. This almost sounds more frightening than the cloak, since there's no reason why the sensors would have to be placed outside. Imagine a world where PHBs can turn their office wall into a window onto any cube. Zero privacy. The technology is great, but the potential for abuse is definitely there." Update: 06/15 00:20 GMT by T : You may remember we mentioned this project when it was cloak-only.

DUPE! (kinda, sorta)

[bluethundr]

Very cool story. Be even cooler if I hadn't seen it before. Right here. [slashdot.org] And it's a 'merican [optics.org] whose applied for the patent.

The idea of an "invisibility cloak" has made the leap from science fiction books to an international patent application. Ray Alden of North Carolina is attempting to patent a "three dimensional cloaking process and apparatus" for concealing objects and people (WO 02/067196).

I had this idea years ago but...

[damieng]

quickly discarded it because it would fail as soon as the observer moved or looked at it from a slight angle - the problem being of course the system has no way of knowing where a viewer might be to correctly map the 'camera' to the right 'display cell'.

Re:Two vids of it in action...

[Anonymous Coward]

Bah...

Link 1 [u-tokyo.ac.jp]
Link 2 [u-tokyo.ac.jp]

Old News

[douthat]

I remeber reading about this in last year's "Coolest Inventions of 2003" located here [time.com] Further investigation has also found that a guy registered a pantent for the same tech back in 2002 [optics.org] From the article:

The idea hinges on carefully mimicking background lighting conditions to help render an object invisible, similar to how a chameleon blends in with its surroundings. The rear and front surfaces of an object are covered with a material containing an array of photodetectors and light emitters respectively.

The photodetectors on the rear surface are used to record the intensity and color of a source of illumination behind the object. The light emitters on the front surface then generate light beams that exactly mimic the same measured intensity, color and trajectory. The result is that an observer looking at the front of the object appears to see straight through it.

and another 2003 article from Wired [wired.com]

Re:No. not really

[WarriorPoet42]

First, what you speak of already exists. They are called either automatic or active windows. However they wouldn't work to well for walls because LCD exists in two states. Black and transparent. I don't know about you, but I don't like the idea of a black wall. A heavily shaded window is okay, but a black wall is horrid!

Re:DUPE! (kinda, sorta)

[nyteroot]

Also, the submitter seems a little retarded..

Imagine a world where PHBs can turn their office wall into a window onto any cube.

Sure: tv fitted in wall, hidden cameras in cubes.

Re:No. not really

[Jah-Wren Ryel]

In other words, when the wall's off, it's opaque. When current's applied to a section, the liquid inside the wall becomes clear and the wall is see-through. Not sure if the technology's there yet, though....

Yeah, it has been around for quite some time, here is just one of many articles on it: Smart Glass [glassonweb.com]

One of my client's has their entire NOC done up with this kind of glass. Just one of the excesses of the dot-com era.

This stuff ain't cheap, but there is even more expensive versions that go black instead of translucent white (and default to clear when there is no current). I desperately want some of that for my car's windows. Alas it is so expensive that the people selling it don't even talk to small fry like I.

Re:No. not really

[EvilTwinSkippy]

LCD's are also available in grey.

And for large LCD's you can control the opacity by trottling the current.

Not all it's cracked up to be

[azav]

At the San Francisco Wired Tech fest, the coat was demoed and to be honest, it didn't appear (to me) to work very well.

I'm sure it is in its infancy but you've got to be looking at the subject DEAD ON and with perfect lighting.

This is one technology that looks much better in photos than it does in real life.

Re:I had this idea years ago but...

[EvilTwinSkippy]

You can fake holography with the right transform equations. The trick is knowing enough about the sensor you are trying to fool to come up with the reference waveform, and having a pixel density enough to not set off aliasing.

If you've ever seen the Marine's new camo, it does this already. The pattern printed on the uniform is so dense and ambigious that the seem to blend into office walls or rocks. It's not that the suit is generating anything wierd, it's that your eye can't pick up any particular shape.

It's the optical equivilent of chaffing a radar.

Re:Future of armed infantry

[baxissimo]

It requires an image to be project on the material.

Actually it's worse than that. It requires the image be projected from the onlooker's point of view. That's what they mean by HMP (==head-mounted projector) So for army dudes to use this, they'd have to actually run up to the enemy, and surreptitiously slap a projector on the head of each bad guy they wanted to hide from, then run back and go about their business of avoiding detection. There's probably a greater liklihood of success basing your military tactics on lethally funny jokes [jumpstation.ca].

And before the cameras...

[Trejkaz]

...we had mirror glass.

Re:Future of armed infantry

[aka-ed]

It's way more complicated than that:

In Susumu Tachi's cloaking system, a camera behind the wearer feeds background images through a computer to a projector, which paints them on a jacket as though it were a movie screen. The wearer appears mysteriously translucent - as long as observers are facing the projection head-on and the background isn't too bright.

To Achieve true invisibility, optical camouflage must capture the background from all angles and display it from all perspectives simultaneously. This requires a minimum of six stereoscopic camera pairs, allowing the computer to model the surroundings and synthesize the scene from every point of view. To display this imagery, the fabric is covered with hyperpixels, each consisting of a 180 x 180 LED array behind a hemispherical lens. This is fantastic, although I'd rather drink a potion.

http://www.kevinrewatts.com/filter/archives/2003_0 7.html

Re:Future of armed infantry

[(C)0N0(R)]

those ribbed plastics (can it, beavis) that show different parts of the image depending on the angle... and thus alow simple animation and 3-d looking objects through small movements.

they are called lenticular devices or often "winkie" - see http://www.didik.com/3d_hist.htm

Re:The evils of technology!

[Tokerat]

Ackbar isn't a cliche on /. and therefore you can be modded up for the geek reference

Re:Window Offices Galore!

[Syre]

I saw the cloak demonstrated last month and talked to the U. of Tokyo people who were showing it and I have to tell you: this is about the lamest thing ever.

THERE IS NO TECHNOLOGY THERE AT ALL!

It's a grey cloak. That's it. A grey cloak. You look at it, and it's a grey cloak. Nothing special at all. But no, "please look at the video monitor!"

Oh, in the video monitor the cloak is sorta transparent. Why? Because they're doing an absolutely standard compositing effect IN THE VIDEO MONITOR.

The cloak is NOT transparent. It's just a piece of blue screen and they composite the background on it. But only if you look at a video monitor. In real life, the cloak is entirely opaque and it's just a grey cloak.

I asked the professor how long it would be before they had a real working prototype and he said "Maybe 20 years."

In other words, they have nothing. Just a concept. And it's not even a new concept. It's an old science fiction concept.

There is nothing to see here. It's just PR and a very standard old-hat video effect.

Re:Future of armed infantry

[willCode4Beer.com]

I was a combat engineer in the US Army.

All of our pockets were button up. The only velco in my uniform was on the parachute retention straps for my helmet.

High technology, what? I had to carry around a 40lb picket pounder. tech is a big steel tube with handles on the sides. my other piece of high tech was a mine probe, basically a fibre-glass stick that you poke into the ground looking for mines.

I always thought the high tech stuff was a joke. I only ever saw it on TV. On TV you got guys with portable ground penetrating radar looking for mines from a distance. In the field, you have a guy crawling on his belly poking a stick in the ground.